State v. Grell

SUPREME COURT OF ARIZONA
En Banc

STATE OF ARIZONA, ) Arizona Supreme Court
) No. CR-01-0275-AP
Appellee, )
) Maricopa County
v. ) Superior Court
) No. CR 1999-095294
SHAWN RYAN GRELL, )
)
Appellant. ) O P I N I O N
__________________________________)

Appeal from the Superior Court in Maricopa County
The Honorable Barbara M. Jarrett, Judge

AFFIRMED IN PART; SENTENCE VACATED;
REMANDED FOR RESENTENCING

________________________________________________________________

TERRY GODDARD, ARIZONA ATTORNEY GENERAL Phoenix
By Kent E. Cattani, Chief Counsel,
Capital Litigation Section
Amy S. Pignatella Cain, Tucson
Assistant Attorney General
Attorneys for the State of Arizona

JAMES J. HAAS, MARICOPA COUNTY PUBLIC DEFENDER Phoenix
By James R. Rummage, Deputy Public Defender
Attorneys for Shawn Ryan Grell

________________________________________________________________

B E R C H, Vice Chief Justice

¶1 Appellant Shawn Grell was convicted of first degree

murder in 2000 following a bench trial on stipulated facts.

After an aggravation and mitigation hearing, the judge sentenced
Grell to death. While Grell prepared his direct appeal, the

United States Supreme Court decided cases that held (1) that

juries must find the aggravating factors that allow the

imposition of a sentence of death, Ring v. Arizona (Ring II),

536 U.S. 584 (2002), and (2) that mentally retarded defendants

may not be executed, Atkins v. Virginia, 536 U.S. 304 (2002).

In addition to raising sentencing issues under Ring, Grell

claimed on appeal that, under Atkins, his mental retardation

should preclude a death sentence in his case. In lieu of

reviewing Grell’s sentence for harmless error, this court

ordered the trial court to re-examine the issue of Grell’s

mental retardation, applying the standards articulated in

Atkins. State v. Grell (Grell I), 205 Ariz. 57, 63, ¶ 41, 66

P.3d 1234, 1240 (2003). On February 2, 2005, the trial court

held another hearing and issued its ruling finding no mental

retardation.

¶2 For the appeal, this court ordered the parties to

combine briefings on both the sentencing issues and the mental

retardation issues. We have jurisdiction under Article 6,

Section 5(3) of the Arizona Constitution and Arizona Revised

Statutes (“A.R.S.”) section 13-4031 (2001). We affirm the trial

court’s finding that Grell did not prove mental retardation, but

remand the case for jury sentencing.

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I. FACTS1

¶3 On December 2, 1999, Shawn Grell picked up his two-

year-old daughter, Kristen, from daycare. They drove around for

several hours, during which time Grell bought a plastic gas can

and gasoline. He then drove to a deserted area in Mesa, put his

sleeping daughter on the ground, poured gasoline on her, and lit

her on fire. She awoke and stumbled several feet while engulfed

in flames before eventually succumbing to the smoke and flames.

Grell drove to a nearby convenience store to buy beer. He told

the clerk he had seen some kids set a dog on fire in a vacant

lot. After driving around for several hours, Grell called the

police and turned himself in at five o’clock the next morning.

He later held a press conference at which he admitted killing

his daughter.

¶4 Grell was charged with first degree murder and child

abuse. He waived a jury trial and instead the parties submitted

to the trial judge a twenty-page narrative with forty-four

attachments to serve as a basis for determining guilt. In

September 2000, the judge convicted Grell of first degree

murder, but acquitted him of child abuse.

¶5 Grell agreed to the admission of the documents at the

1
A more complete account of the crime appears in Grell I,
205 Ariz. at 58-59, ¶¶ 3-15, 66 P.3d at 1235-36.

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sentencing hearing, but attempted to preserve his right to a

jury trial on sentencing issues by the following language:

“This stipulation shall in no way constitute a waiver of any

rights the defendant may have to have a jury empanelled to

determine the existence or absence of any aggravating and or

mitigating circumstances.” When Grell specifically requested

that a jury be empanelled for the sentencing proceeding,

however, the motion was denied.

A. Original Sentencing

¶6 The combined aggravation and penalty phase hearing

held in June 2001 included testimony from mental health experts,

law enforcement officers, a burn injury expert, and Grell’s

sister. The State asserted three statutory aggravating factors:

that Grell had previously been convicted of a serious offense;

that the crime was committed in an especially heinous, cruel, or

depraved manner; and that the victim was younger than fifteen

years of age. See A.R.S. § 13-703(F)(2), (F)(6), (F)(9) (1999).

The trial court found all three.

¶7 The prior serious offense was a 1996 conviction for

robbery. See A.R.S. § 13-703(H) (1999) (identifying robbery as

a “serious offense” for purposes of use as a death penalty

aggravator). That Kristen was younger than fifteen at the time

of the crime was proven by a birth certificate showing her 1997

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birthdate, which established that she was two years old at the

time of her death.

¶8 Citing the facts that Kristen was conscious when set

on fire, that she had to have suffered immense physical pain,

and that Grell should have foreseen the pain she would suffer,

the court also found the crime “especially cruel.” In addition,

while acknowledging that only a finding of cruelty was necessary

to satisfy the § 13-703(F)(6) aggravating factor, the court also

found the crime heinous and depraved.2 The court cited the

following factors in making these findings: (1) the crime was

senseless; (2) the victim was helpless; (3) the victim was the

defendant’s own child; (4) the method of killing ensured that

the victim would suffer “unimaginable pain”; (5) the method

ensured that the body would be disfigured; and (6) the defendant

made comments to a convenience store clerk after the murder

about seeing a dog set on fire.3 The court stated that these

2
The “heinous, cruel, or depraved” aggravator is written in
the disjunctive and the state need prove only one of the three
conditions to trigger application of the aggravating
circumstance. State v. Gretzler, 135 Ariz. 42, 51, 659 P.2d 1,
10 (1983). Heinousness and depravity are, however, frequently
analyzed together as both involve the defendant’s mental state.
Id.
3
The trial court’s Special Verdict does not explain the
import of this factor, but we infer from the subsequent citation
to Gretzler that the judge meant that the defendant relished his
crime. See Gretzler, 135 Ariz. at 52, 659 P.2d at 11.

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facts satisfied the test set forth in State v. Gretzler, 135

Ariz. 42, 659 P.2d 1 (1983), and concluded that the manner of

killing, in addition to being cruel, was also heinous and

depraved.

¶9 In mitigation, Grell alleged the statutory mitigating

circumstance of mental impairment, see A.R.S. § 13-703(G)(1), as

well as non-statutory mitigators of mental retardation, learning

disabilities, difficult childhood, and remorse. Much of the

evidence at the hearing centered on Grell’s claims of mental

impairment, mental retardation, and a cognitive disorder caused

by brain damage.

¶10 Drs. Globus and Wicks testified for the defense and

Drs. Mayberg and Scialli testified for the State. On the issues

of mental impairment and brain damage, Dr. Globus testified that

he initially diagnosed Grell with brain damage before having a

PET scan done and before having Dr. Wicks do a blind

neuropsychological evaluation of Grell. Dr. Globus is not

certified to read PET scans, and those who prepared the report

for him did not testify, facts noted by the court in its

sentencing decision. Dr. Mayberg, the State’s neuropsychologist

who is qualified to read PET scans, testified that Grell’s PET

scan showed no brain damage. Dr. Scialli testified that he

found no evidence of a cognitive disorder caused by brain

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damage, but instead diagnosed Grell as having only an anti-

social personality disorder.

¶11 The trial court ultimately found “no credible

evidence” that Grell suffered from brain damage. The court

instead accepted Dr. Scialli’s diagnosis that Grell suffered

from an anti-social personality disorder, symptoms of which

include acting impulsively and using poor judgment.

¶12 Drs. Globus and Wicks also testified regarding Grell’s

mental retardation, as did Dr. Scialli. The court acknowledged

Grell’s low IQ scores, ranging from 65 to 74, but weighted more

heavily Dr. Scialli’s testimony that Grell had adequate adaptive

skills.4 In addition, the trial court observed that no one

before Drs. Globus and Wicks had ever diagnosed Grell as having

mental retardation and that Grell had demonstrated good adaptive

skills by maintaining a false identity in order to be charged as

a juvenile after he was arrested for robbery in 1996 when he was

twenty years old.

4
The court did not state its criteria for determining mental
retardation, but the discussion of IQ scores and adaptive skills
covers two of the three factors cited by the Supreme Court in
Atkins and this court in Grell I as useful in determining the
existence of mental retardation: low IQ, poor adaptive skills,
and onset before age eighteen. The criteria are based on the
Diagnostic Criteria for Mental Retardation, Diagnostic &
Statistical Manual of Mental Disorders (4th ed. 1994) (“DSM-IV”)
and are substantially consistent with the statutory definition
in A.R.S. § 13-703.02(K)(2) (2002), which was enacted after
Grell’s sentencing.
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¶13 Finding no mitigation sufficiently substantial to call

for leniency, the judge sentenced Grell to death.

B. First Appeal

¶14 An automatic notice of appeal was filed. While the

parties prepared for oral arguments, the United States Supreme

Court handed down opinions in Atkins, 536 U.S. at 304, and Ring

II, 536 U.S. at 584. This case was consolidated with other

capital cases pending on direct appeal at the time for the

purpose of deciding common Ring issues. State v. Ring (Ring

III), 204 Ariz. 534, 65 P.3d 915 (2003). This court issued a

decision in Grell I without considering the sentencing issues.

205 Ariz. at 60, ¶ 25, 66 P.3d at 1237.

¶15 In Grell I, 205 Ariz. at 58, ¶ 2, 66 P.3d at 1235,

this court addressed Grell’s trial issue and affirmed his

conviction, but remanded the matter to the trial court for a re-

evaluation of Grell’s mental retardation claim in light of

Atkins. The trial court had evaluated the mental retardation

evidence as a mitigating factor rather than as a complete bar to

execution. This court suggested that, on remand, the trial

judge should apply A.R.S. § 13-703.02 as a guide in future

proceedings to ascertain the existence of mental retardation.5

5
Section 13-703.02, enacted before Atkins issued but after
Grell’s sentencing, defines the pretrial process for evaluating
mental retardation in capital cases. First, the trial judge
- 8 -
Id. at 64, ¶ 42, 66 P.3d at 1241.

C. Remand for Mental Retardation Hearing

¶16 Attempting to follow the procedures in A.R.S. § 13-

703.02, the trial judge first suggested appointing a “pre-

screening expert” to test Grell’s IQ. Rather than subjecting

Grell to additional testing, the State and the defense

stipulated that Grell’s IQ was less than 70 and that further IQ

testing was unnecessary.

¶17 Before the mental retardation hearing, the parties

briefed and argued the issue of burden of proof. The statute

places the burden on the defendant to prove mental retardation

by clear and convincing evidence. A.R.S. § 13-703.02(G). Grell

argued, however, that because mental retardation serves as a

constitutional bar to execution, the standard should be no

appoints a pre-screening expert to administer an IQ test to the
defendant. A.R.S. § 13-703.02(B). If the resulting score is 75
or below, the judge picks one expert nominated by each party, or
one jointly nominated expert, to test the defendant again.
A.R.S. § 13-703.02(D). If any test result is 70 or below, the
court conducts a hearing at which the defendant must prove by
clear and convincing evidence that he has “significantly
subaverage general intellectual functioning [an IQ of 70 or
lower], existing concurrently with significant impairment in
adaptive behavior, where the onset of the foregoing conditions
occurred before the defendant reached the age of eighteen.”
A.R.S. § 13-703.02(G), (K). If the court finds that the
defendant’s IQ is 65 or below, a rebuttable presumption of
mental retardation arises. A.R.S. § 13-703.02(G). If the court
does not find mental retardation, the defense may still argue
the issue to the jury as a mitigating factor. A.R.S. § 13-
703.02(H).
- 9 -
higher than a preponderance of the evidence. Rejecting Grell’s

claim, the trial court required Grell to prove mental

retardation by clear and convincing evidence.

¶18 During preparations for the hearing on remand, a new

defense expert, Dr. Denis W. Keyes, interviewed Grell. The

State requested that Grell also submit to examination by its new

expert, Dr. Dan Martel. Before Dr. Keyes completed his report

and before meeting with Dr. Martel, Grell told his attorneys he

was “not willing to cooperate any further with any of our

experts or investigators.” Shortly thereafter, Dr. Keyes

completed his report, which concludes that Grell has mental

retardation.

¶19 After receiving Grell’s written refusal to be

examined, the State moved to “Preclude Defendant’s Additional

Mental Health Professional.” The defense, which did not yet

have Dr. Keyes’ report, did not respond to the motion. As a

result of these circumstances, the trial court granted the

State’s motion to preclude Dr. Keyes from testifying. After

receiving Dr. Keyes’ report, the defense filed a Motion to

Reconsider, which was denied.

¶20 Following the motion and Grell’s refusal to cooperate,

each side determined that it had no additional evidence to

present and would rely on the evidence presented at the June

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2001 hearing. The court held oral argument on December 7, 2004,

at which each side argued from the same documents and the same

testimony to the same judge as in the first hearing. Quoting

extensively from the record and noting that it had previously

found the State’s experts more persuasive, the trial court found

nothing “to change its mind” and concluded that Grell had failed

to satisfy his burden of proving mental retardation by clear and

convincing evidence.

II. DISCUSSION

A. The Burden of Proof and Standard for Proving Mental
Retardation

¶21 Grell’s major argument on this appeal is that the

trial court used a flawed process in finding that he does not

have mental retardation. He raises three challenges to the

process: First, the State should bear the burden of proving

lack of retardation to a jury beyond a reasonable doubt.

Second, if the defendant must bear the burden of proof, the

standard should be no higher than a preponderance of the

evidence; the statutory requirement of clear and convincing

evidence is unconstitutionally high. Third, the process should

be bifurcated, with both a pretrial hearing before a judge to

determine, under Atkins, whether mental retardation should bar

the defendant’s execution and, should the judge not find mental

retardation, a jury component in which the jury must find,
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beyond a reasonable doubt, that the defendant does not have

mental retardation.6

¶22 Grell’s challenges raise issues of constitutional law

and statutory construction, which we review de novo. State v.

Moody, 208 Ariz. 424, 445, ¶ 62, 94 P.3d 1119, 1140 (2004). In

analyzing statutes, however, we begin by assuming the statute is

constitutional. State v. Casey, 205 Ariz. 359, 362, ¶ 11, 71

P.3d 351, 354 (2003).

1. Imposing burden on defendant to prove mental
retardation

¶23 For the hearing to determine whether Grell has mental

retardation, this court instructed the trial court to apply the

procedures in A.R.S. § 13-703.02 “insofar as is practical in the

post-trial posture of this case.” Grell I, 205 Ariz. at 64,

¶ 42, 66 P.3d at 1241. The statute places on “the

defendant . . . the burden of proving mental retardation by

clear and convincing evidence” in the pretrial hearing. A.R.S.

§ 13-703.02(G). If the defendant’s IQ is 65 or lower, a

rebuttable presumption of mental retardation arises. Id.

Because the parties here stipulated that Grell’s IQ falls

between 65 and 70, the trial court accordingly placed the burden

6
The statute currently provides for a bifurcated process,
see supra note 5, but the jury hears the mental retardation
evidence only as a mitigating factor. See A.R.S. § 13-
703.02(H).
- 12 -
on him to prove by clear and convincing evidence that mental

retardation renders him ineligible for execution. Grell argues

that if the defendant must bear the burden at all, the standard

should be to prove retardation by no more than a preponderance

of the evidence.

¶24 This issue reaches our court because in Atkins, the

Supreme Court declined to specify the procedures that states

should use to identify mentally retarded individuals, deferring

to the states to develop appropriate procedures. Atkins, 536

U.S. at 317. The Court did so in part in acknowledgement of the

lack of consensus regarding which defendants have mental

retardation:

To the extent there is serious disagreement about the
execution of mentally retarded offenders, it is in
determining which offenders are in fact
retarded. . . . Not all people who claim to be
mentally retarded will be so impaired as to fall
within the range of mentally retarded offenders about
whom there is a national consensus. As was our
approach in Ford v. Wainwright, 477 U.S. 399, 106
S.Ct. 2595, 91 L.Ed.2d 335 (1986), with regard to
insanity, “we leave to the State[s] the task of
developing appropriate ways to enforce the
constitutional restriction upon [their] execution of
sentences.” Id. at 405, 416-417, 106 S.Ct. 2595.

Atkins, 536 U.S. at 317. Although left to the states, the

procedures developed must comport with the Constitution.

¶25 The Supreme Court has confirmed that states may

“‘regulate the procedures under which [their] laws are carried

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out, including the burden of producing evidence and the burden

of persuasion,’ and [their] decision[s] in this regard [are] not

subject to proscription under the Due Process Clause unless

‘[they] offend[] some principle of justice so rooted in the

traditions and conscience of our people as to be ranked

fundamental.’” Patterson v. New York, 432 U.S. 197, 201-02

(1977) (quoting Speiser v. Randall, 353 U.S. 513, 523 (1958));

see also Medina v. California, 505 U.S. 437, 445 (1992) (calling

Patterson the “proper analytical approach” in evaluating burdens

of proof). Grell claims that imposing the burden on a defendant

to prove mental retardation by clear and convincing evidence

does offend deeply rooted principles.

¶26 Grell initially argues that the burden on the issue of

mental retardation should not fall on the defendant at all, but

rather should be borne by the State. We disagree that the

Constitution requires the prosecution to bear this burden. The

Supreme Court has held that a state may require that the

defendant prove affirmative defenses. E.g., Patterson, 432 U.S.

at 206 (requiring the defendant to prove extreme emotional

disturbance); Martin v. Ohio, 480 U.S. 228, 236 (1987)

(requiring the defendant to prove self defense). Proof of

mental retardation is like proof of an affirmative defense in

that it serves to relieve or mitigate a defendant’s criminal

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responsibility, and as with affirmative defenses, the evidence

of retardation will lie largely within the possession and

control of the defendant.

¶27 Because the defendant has superior access to the

evidence to prove his mental condition, it is not inappropriate

to place the burden on him to do so. See Medina, 505 U.S. at

455 (O’Connor, J., concurring); cf. Patterson, 432 U.S. at 206

(to same effect). A critical component of proof of mental

retardation is onset before age eighteen. The defendant has

better information regarding his condition and superior access

to friends and family who knew him before he turned eighteen.

Moreover, a defendant has significant motivation to attempt to

score poorly on an IQ test, a low score on which triggers a

claim of mental retardation. See A.R.S. § 13-703.02(B). Such

evidence lies within the defendant’s control and may prove

difficult for the state to rebut.

¶28 New Jersey is the only state, as of this writing, to

place the burden of disproving mental retardation on the state.

State v. Jimenez, 880 A.2d 468, 484 (N.J. Super. Ct. App. Div.

2005). It did so because state law developed under the

Ring/Apprendi line of cases treats certain statutory “capital

triggers” like aggravating factors that the state must prove to

a jury beyond a reasonable doubt. Id. at 482-84 (discussing the

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implications of Ring II, 536 U.S. at 584, and Apprendi v. New

Jersey, 530 U.S. 466 (2000)). The court in Jimenez held that

mental retardation was essentially such a “capital trigger,”

which under New Jersey law the state must prove beyond a

reasonable doubt. 880 A.2d at 484. Because, however, the

absence of mental retardation is neither an aggravating factor

nor an element of the capital offense under Arizona law, the

rationale supporting the result in Jimenez does not apply here.

¶29 We find no constitutional bar to imposing the burden

of proving mental retardation on the defendant.

2. Imposition of the “clear and convincing evidence”
standard

¶30 Citing Cooper v. Oklahoma, 517 U.S. 348 (1996), Grell

asserts the unconstitutionality of requiring him to prove mental

retardation by clear and convincing evidence. In Cooper, the

Court, having already declared that the defendant must bear the

burden of proving competency to stand trial, id. at 355, held

that the defendant may not be forced to prove his competency by

clear and convincing evidence. Id. at 369. The Court evaluated

the right not to be tried while incompetent and weighed the

impact of its loss on the defendant to determine the appropriate

standard of proof. Id. at 354, 364. The Court observed that

the right not to be tried if incompetent is a fundamental

“principle of justice [so] rooted in the traditions and
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conscience of our people” that its violation “threatens . . .

the basic fairness of the trial itself.” Id. at 364.

¶31 Furthermore, the Court reasoned, the heightened

standard of proof affected only those defendants who could prove

they were incompetent, but could not do so by clear and

convincing evidence. Id. at 366-67. The higher standard

affected those defendants’ only opportunity to contest

competency, creating a grave risk of violating their right not

to be tried while incompetent. Id. The Court concluded that

the defendants’ interest outweighed the government’s lesser

interest in trying a probably incompetent defendant. Id. The

Court also noted that forty-six other state jurisdictions used a

lower standard of proof, showing consensus that Oklahoma’s

higher standard was unnecessary to serve the state’s needs and

inappropriate in light of the importance of the right. Id. at

361-62. The Court therefore held that due process limits the

burden on the defendant to prove competency to stand trial by a

standard no higher than preponderance of the evidence. Id. at

368-69.

¶32 As was the Court in Cooper, we have been asked to

assess the statutory imposition of a clear and convincing

evidence standard in a situation in which a preponderance

standard would be permissible. Although the right not to be

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executed if mentally retarded is of recent vintage, it — like

the right not to stand trial if incompetent — is a

constitutional right based on modern consensus and historical

views regarding the propriety of executing those who may be

“less morally culpable” because of their reduced mental

capacity. See Atkins, 536 U.S. at 320-21. We also note that,

following Atkins, all but one jurisdiction that has chosen a

burden has chosen preponderance of the evidence.7 We might have

done so as well, were there no Arizona statute already in place.

The question before us, however, is whether the standard chosen

by the legislature to protect admittedly important state

interests can withstand constitutional scrutiny.

7
The following statutes, passed in 2003 after Atkins, impose
a preponderance standard: Cal. Penal Code § 1369 (West, Westlaw
through 2006 Sess.); Idaho Code Ann. § 19-2515A (Westlaw through
2005 Sess.); 725 Ill. Comp. Stat. Ann. 5/114-15 (West, Westlaw
through 2005 Sess.); Nev. Rev. Stat. Ann. § 174.098 (West,
Westlaw through 2005 Sess.); Utah Code Ann. § 77-15a-104 (West,
Westlaw through 2005 2d Sess.); Va. Code Ann. § 19.2-264.3:1.1
(West, Westlaw through 2005 Sess.). The following cases, from
jurisdictions in which no statute sets a burden, set
preponderance as the appropriate standard: State v. Williams,
831 So. 2d 835, 860 (La. 2002); Russell v. State, 849 So. 2d 95,
148 (Miss. 2003); State v. Lott, 779 N.E.2d 1011, 1015 (Ohio
2002); Commonwealth v. Mitchell, 839 A.2d 202, 211 n.8 (Pa.
2003); Franklin v. Maynard, 588 S.E.2d 604, 606 (S.C. 2003); Ex
parte Briseno, 135 S.W.3d 1, 12 (Tex. Crim. App. 2004).
Delaware, which passed its statute within a month of
Atkins, is the lone exception. Del. Code Ann. Tit. 11, § 4209
(West, Westlaw through 2005 Sess.) (imposing a clear and
convincing burden). Of the eighteen states that had statutes in
place before Atkins, thirteen states use the preponderance
standard. See Atkins, 536 U.S. at 314-15 & nn.12-15.
- 18 -
¶33 The statutory scheme enacted by the Arizona

legislature does not merely prohibit execution of the mentally

retarded. It provides a detailed, bifurcated process that

requires a pretrial hearing at which a defendant may attempt to

show, by clear and convincing evidence, that he has mental

retardation; if he fails to make that showing, the defendant may

still present mental retardation evidence to the jury in

mitigation of his sentence. A.R.S. § 13-703.02. The statutory

process gives the defendant with an IQ of 75 or below the

opportunity to be examined by at least two psychological experts

to determine his IQ. A.R.S. § 13-703.02(B), (D). Those with at

least one full-scale IQ test result of 70 or below proceed for

further evaluation and an evidentiary hearing. A.R.S. § 13-

703.02(F), (G). Although the defendant bears the ultimate

burden to prove mental retardation, the statute creates a

rebuttable presumption of mental retardation if the defendant’s

IQ is 65 or below. A.R.S. § 13-703.02(G).8

¶34 The Arizona statute sets up a process similar to that

8
By selecting an IQ of 65 as the number that gives rise to
the presumption of retardation — which presumption assumes the
existence of “significantly subaverage general intellectual
functioning,” concurrent “significant impairment in adaptive
behavior,” and onset before age eighteen, A.R.S. § 13-
703.02(K)(2) — the legislature has given added protection to
those defendants whom the DSM-IV would define as having “mild”
mental retardation. DSM-IV 42-43.

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used in Colorado and Indiana, and courts in both those states

have evaluated the constitutionality of requiring a defendant to

prove mental retardation by clear and convincing evidence.9

Compare People v. Vasquez, 84 P.3d 1019 (Colo. 2004) (approving

use of clear and convincing standard in a pretrial hearing),

with Pruitt v. State, 834 N.E.2d 90 (Ind. 2005) (finding a clear

and convincing standard unconstitutional). Grell and our

dissenting colleague rely heavily on analysis from Cooper that

also formed the basis of the Pruitt opinion. They argue that

the definitive inquiry is the assessment of the relative risks

faced by the parties: the defendant’s risk of death compared to

the state’s minimal interest in executing a defendant who will

otherwise go to prison for life.

9
A Georgia statute requires the defendant to establish
mental retardation by proof beyond a reasonable doubt, a burden
that the Georgia Supreme Court has twice upheld. See Head v.
Hill, 587 S.E.2d 613, 621 (Ga. 2003) (post-Atkins case analyzing
Georgia Code Annotated § 17-7-131 (West, Westlaw through 2005
Special Sess.)); Mosher v. State, 491 S.E.2d 348 (Ga. 1997)
(pre-Atkins case). Because the procedure under the Georgia
statute differs substantially from that under the Arizona
statute, however, we do not rely on the analysis in Head and
Mosher. In those cases, the Georgia Supreme Court found the
twin requirements that the defendant need only demonstrate
incompetence to stand trial by a preponderance of the evidence
and may prove mental retardation to a jury by proof beyond a
reasonable doubt sufficient to safeguard mentally retarded
persons against the special risks of trial to which they are
subject. Head, 587 S.E.2d at 622. Arizona’s safeguards are, if
anything, more protective of the rights of the defendant than
are Georgia’s.

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¶35 With respect to statutes like those in Arizona,

Indiana, and Colorado, however, Grell overstates his case. As

the Colorado Supreme Court stressed in Vasquez, the defendant’s

risk at a pretrial hearing is not death, but a capital trial.10

84 P.3d at 1023. By creating a pretrial process, the

legislature provided a way for mentally retarded defendants to

avoid the burden of a capital trial and the risk of imposition

of the capital penalty. All defendants who do not prove mental

retardation at the pretrial hearing retain the ability to

present mental retardation evidence to the jury under a

preponderance standard in the penalty phase of the trial. That

opportunity reduces the ultimate risk they face from an adverse

determination in the pretrial mental retardation hearing.

¶36 The court in Pruitt acknowledged but rejected the

argument that the defendant’s ability to argue mental

retardation evidence in mitigation to the jury under a

preponderance of the evidence standard adequately safeguards the

defendant’s rights. It reasoned that “[m]entally retarded

defendants in the aggregate face a special risk of wrongful

execution.” 834 N.E.2d at 103 (quoting Atkins, 536 U.S. at

10
Grell’s risk at this post-trial proceeding was of course
different, but the outcome is functionally the same because he
retains the right to present the evidence of mental retardation
to the jury in mitigation. See infra ¶¶ 64-67.

- 21 -
321). Although the acknowledged risk that the Pruitt court

identifies may justify barring the execution of the mentally

retarded, it does not suggest the need for any particular

procedure to ascertain mental retardation. Under Arizona’s

statutory procedure, these defendants about whom there is

consensus against execution will be screened out at the pretrial

stage. Given that fact, we cannot say that those unable to

establish retardation by clear and convincing evidence face such

a severe risk at sentencing that they may not constitutionally

be put through the capital trial process.

¶37 Although the Court in Atkins clearly announced that

states may not execute the mentally retarded, it recognized that

people may disagree over which individuals in fact have mental

retardation. 536 U.S. at 317. Before Atkins, states had

already begun to develop their own procedures, and had drawn in

different places the line for establishing the mental

retardation that would bar execution. Knowing this, the Court

explicitly left the procedure for determining mental retardation

to the states. Id. State procedures must ensure that those

about whom there is national consensus are protected from

execution, but left states otherwise free to craft their laws

for determining which defendants meet the consensus standard.

By providing differing procedures based on the defendant’s IQ,

- 22 -
Arizona law reflects this concept. Those with IQ scores of 65

or below face a comparatively lower bar, while those whose IQ

scores suggest greater intelligence must go to greater lengths

to prove their mental retardation. The legislature placed a

heavier burden on those who do not fall within the group about

whom there is national consensus regarding their right not to be

executed. The procedure occurs early in the capital process and

removes defendants found to have mental retardation from

exposure to a capital trial and hence to a sentence of death.

See A.R.S. § 13-703.02(C), (F), (G). The application of

Arizona’s tiered procedure does not deprive Grell of a right

rooted in fundamental justice.

¶38 Finally, in response to the reliance of the defendant

and our dissenting colleague on the analysis in Cooper, 517 U.S.

at 348, we note the significant differences between the right

not to be tried while incompetent and the right not to be

executed if mentally retarded. First, a defendant found

incompetent to stand trial is protected from having to submit to

trial on any charges unless he is restored to competency. See

id. A defendant deemed to have mental retardation, however, is

not shielded from trial. See Atkins, 536 U.S. at 318. Despite

the risks that a mentally retarded defendant might not present

well to a jury, such a defendant can be tried, found guilty, and

- 23 -
sentenced to any statutory criminal penalty other than death.

This legal distinction suggests that mental retardation differs

constitutionally from incompetence to stand trial.

¶39 The second distinction relates to the risk of

malingering. A defendant who successfully feigns incompetence

to stand trial will not have to submit to trial at that time.

Generally, however, such a defendant is sent to a mental health

facility for treatment and further examination of his

competency. See Ariz. R. Crim. P. 11.5(b)(2)(i). Most often,

the defendant is either restored to competency or discovered to

be malingering. In the event of either occurrence, the

defendant is subject to trial and punishment, including the

death penalty, if appropriate. On the other hand, once a court

determines that a defendant has mental retardation, that

defendant may never suffer the punishment of execution, even if

he is later discovered to have been malingering. These concerns

support the heightened standard that the legislature has imposed

to protect the interests of Arizona citizens.

¶40 A better comparison lies between claims of mental

retardation as a bar to execution and claims of mental

incompetence as a bar to execution. The defendant asserting the

latter claim is also subject to a clear and convincing evidence

burden of proof. See A.R.S. § 13-4022(F) (clear and convincing

- 24 -
burden of proof); Ford v. Wainwright, 477 U.S. 399, 410 (1986)

(holding that the Eighth Amendment prohibits states from

“inflicting the penalty of death upon a prisoner who is

insane”). We are aware of no case finding it violative of the

Constitution to require a defendant to prove incompetence to be

executed by clear and convincing evidence.

¶41 In sum, we conclude that requiring the defendant to

prove mental retardation by clear and convincing evidence in the

initial retardation hearing does not violate constitutional

standards.

3. Jury determination of mental retardation

¶42 Grell argues that, under Ring, the jury must find

beyond a reasonable doubt that the defendant does not have

mental retardation before it may impose a sentence of death.

Furthermore, he argues, the process should be bifurcated: a

judge should make a preliminary finding on mental retardation,

and if the judge finds the defendant death-eligible, the state

still must prove a defendant’s lack of mental retardation beyond

a reasonable doubt to the jury.

¶43 Ring and Apprendi require that a jury find all

functional elements of a crime and all non-admitted facts except

prior convictions that increase the sentence above the

presumptive sentence. See Apprendi, 530 U.S. at 489. Although

- 25 -
mental retardation does indeed involve fact-finding, it is not

the functional equivalent of an element of the crime. It has

nothing to do with the acts that make up the crime itself or the

defendant’s mental state while committing the crime, facts the

state traditionally must prove. As a result, Ring does not

require that a jury find the absence of mental retardation. See

Arbelaez v. State, 898 So. 2d 25, 43 (Fla. 2005); Ex parte

Briseno, 135 S.W.3d 1, 10 (Tex. Crim. App. 2004); Winston v.

Commonwealth, 604 S.E.2d 21, 50 (Va. 2004).

¶44 Nor is the absence of retardation a fact that

increases the available penalty. See Apprendi, 530 U.S. at 490

n.16; see also United States v. Booker, 543 U.S. 220, 244

(2005). The finding that a defendant does not have mental

retardation “neither expos[es] the defendant to a deprivation of

liberty greater than that authorized by the verdict according to

statute, nor . . . impos[es] upon the defendant a greater stigma

than that accompanying the jury verdict alone.” Bowling v.

Commonwealth, 163 S.W.3d 361, 379 (Ky. 2005); see also Head v.

Hill, 587 S.E.2d 613, 619-20 (Ga. 2003); Russell v. State, 849

So. 2d 95, 147-48 (Miss. 2003); State v. Flores, 93 P.3d 1264,

1267 (N.M. 2004); State v. Laney, 627 S.E.2d 726, 731 (S.C.

2006); Howell v. State, 151 S.W.3d 450, 467 (Tenn. 2004). Thus

nothing in the Apprendi line of cases requires that a jury find

- 26 -
the absence of mental retardation beyond a reasonable doubt.

¶45 The Supreme Court itself has signaled that a jury need

not decide the issue of mental retardation. When the Ninth

Circuit suspended federal habeas proceedings in Schriro v. Smith

and ordered a state jury trial on the issue of mental

retardation, the Supreme Court summarily reversed the decision,

implicitly rejecting the conclusion that Atkins requires a jury

trial. 126 S. Ct. 7, 9 (2005) (per curiam). The defendant in

Schriro had argued that he suffered from mental retardation and

could not be executed. Id. at 8. Observing that Arizona and

many states had adopted procedures for adjudicating the mental

retardation question, the Court said, “While those measures

might, in their application, be subject to constitutional

challenge, Arizona had not even had a chance to apply its chosen

procedures when the Ninth Circuit preemptively imposed its jury

trial condition.” Id. at 9. Although we hesitate to read too

much into the summary reversal, we draw from it a suggestion

that a jury trial is not required.

¶46 Grell also compares the mental retardation finding to

Enmund/Tison findings, arguing that both are findings of fact

that should be made by the jury beyond a reasonable doubt. See

Tison v. Arizona, 481 U.S. 137 (1987); Enmund v. Florida, 458

U.S. 782 (1982). The analysis fails for two reasons. First,

- 27 -
the Supreme Court has held that Enmund/Tison findings, that a

defendant actually killed or intended to kill, need not be made

by a jury. See Cabana v. Bullock, 474 U.S. 376, 385-86 (1986),

abrogated on other grounds by Pope v. Illinois, 481 U.S. 497,

503 n.7 (1987). The Court’s reasoning — that Enmund/Tison

findings serve to disqualify an otherwise seemingly death-

eligible defendant from death — suggests that that part of the

opinion will survive Apprendi, because the findings mitigate

rather than aggravate a potential sentence. Id.; see also Ring

III, 204 Ariz. at 564, ¶ 100, 65 P.3d at 945 (concluding that

Cabana survives Apprendi because it involves an Eighth Amendment

proportionality analysis, traditionally done by a trial judge).

Similarly, mental retardation serves to exclude a defendant from

eligibility for the death penalty; its absence does not render

an otherwise ineligible defendant eligible for the death

penalty.

¶47 Second, Enmund/Tison findings lend themselves more

logically to proof beyond a reasonable doubt than does proof of

mental retardation. Enmund/Tison findings are based on evidence

of participation in the crime and intent. Mental retardation,

on the other hand, requires evaluation of the defendant’s past

and present mental functioning, using documentation and evidence

largely within the control of the defendant. Placing the burden

- 28 -
on the prosecution to prove lack of retardation beyond a

reasonable doubt would require it to prove a negative against a

party with a motive to misrepresent his mental health and his

past. The burden on the prosecution would be almost impossibly

high.

¶48 Grell argues not only that the jury should hear the

mental retardation evidence in mitigation, but also that it

should decide whether mental retardation should serve as a bar

to execution following an initial determination by the trial

judge on that issue. Because Atkins left the procedure for

determining mental retardation to the states, such a procedure

would not be prohibited; but neither is it required. Indeed,

the statute already requires that both the judge and jury

evaluate mental retardation before a sentence of death may be

imposed. The judge hears mental retardation evidence as a legal

bar to execution and the jury hears it for mitigation purposes.

¶49 Grell acknowledges that having the jury serve as the

only arbiter of mental retardation is not wise. The

difficulties a mentally retarded person may have in testifying,

communicating, and expressing remorse may negatively influence

the jury. That factor formed an explicit basis of the Supreme

Court’s prohibition on execution of the mentally retarded. See

Atkins, 536 U.S. at 320-21. But because the statute requires an

- 29 -
initial judicial determination, Grell’s concern is ameliorated.

The trial court did not err in determining that a jury need not

determine mental retardation as a bar to execution.

B. Preclusion of Testimony from Defense Expert Dr. Keyes

¶50 Defense counsel protests the exclusion of his third

mental health expert as an unnecessarily harsh penalty for

Grell’s refusal to cooperate with the State’s third mental

health expert. “Whether to preclude . . . a witness’s testimony

lies within the discretion of the trial court.” Moody, 208

Ariz. at 457, ¶ 135, 94 P.3d at 1152. We will not reverse a

sanction unless the trial court has abused its discretion. Id.

¶51 The State moved to preclude Dr. Keyes from testifying

about Grell’s adaptive abilities after Grell refused to

cooperate with the State’s new mental health expert. Relying on

State v. Druke, 143 Ariz. 314, 693 P.2d 969 (App. 1984), and

State v. Schackart, 175 Ariz. 494, 858 P.2d 639 (1993), the

trial court granted the State’s unopposed motion. Concluding

that it would be unfair to the State to allow the new defense

expert when the State’s new expert could not examine Grell, the

court also denied the defense Motion to Reconsider, filed after

Dr. Keyes filed a report concluding that Grell has mental

retardation.

¶52 Defense counsel argues that Druke, Schackart, and

- 30 -
cases relating to insanity experts should not control Grell’s

case because mental retardation differs from insanity or

impulsive behavior. Mental retardation, by definition, must

exist before age eighteen. Grell argues that his current mental

condition is therefore of only limited relevance. The State’s

expert, Dr. Scialli, stated as much in his testimony. Grell

also emphasizes the difference between requiring the State to

face a defense expert with no expert of its own, and having it

face three defense experts with two experts of its own. The

latter situation, he argues, does not prejudice the State’s

case.

¶53 While it may be true that an expert could have

evaluated Grell’s adaptive skills without interviewing him, the

controlling statute defines mental retardation as including

current impairment in adaptive ability. See A.R.S. § 13-

703.02(K). Assessments based on recent interviews of the

defendant are thus persuasive. Accordingly, the trial judge has

discretion to preclude mental health experts as a sanction for

the defendant’s refusal to cooperate with interviews and

testing. Phillips v. Araneta, 208 Ariz. 280, 285, ¶ 15, 93 P.3d

480, 485 (2004). Although such a sanction weighs especially

heavily in a capital case, faced with the State’s reduced

ability to rebut Dr. Keyes’ assessment of Grell’s current

- 31 -
functioning, the judge did not abuse her discretion by

precluding Dr. Keyes’ testimony.

C. Denial of Motion to Strike Testimony of Dr. Scialli

¶54 The defense argues that Dr. Scialli is not a qualified

expert under A.R.S. § 13-703.02, the pretrial screening statute

the trial court was attempting to follow, and his testimony

should therefore have been precluded.

¶55 Whether a statute applies in a particular situation is

a question of law, which we review de novo. Schoneberger v.

Oelze, 208 Ariz. 591, 594, ¶ 12, 96 P.3d 1078, 1081 (App. 2004).

We review the decision to admit or exclude evidence for abuse of

discretion. State v. Aguilar, 209 Ariz. 40, 49, ¶ 29, 97 P.3d

865, 874 (2004).

¶56 Section 13-703.02(K)(3) defines a “psychological

expert” as “a psychologist licensed pursuant to title 32,

chapter 19.1 with at least two years’ experience in the testing,

evaluation and diagnosis of mental retardation.”11 Dr. Scialli

is a psychiatrist, not a psychologist. The record shows that he

11
Section 32-2071 requires a “doctoral degree” from an
accredited program in any of several areas of psychology. The
program must include hundreds of hours of supervised training.
A.R.S. § 32-2071(D). Among the required subjects of study are
“interviewing and the administration[,] scoring and
interpretation of psychological test batteries for the diagnosis
of cognitive abilities and personality functioning.” A.R.S.
§ 32-2071(A)(4)(g). Psychiatrists have medical training and
receive an M.D. rather than a Ph.D.
- 32 -
has had training in mental retardation for a child psychiatry

fellowship, has been a consultant with several government

agencies, has “evaluated and consulted on” children with mental

retardation for Child Protective Services, and has been the

acting medical director for the Division of Developmental

Disabilities, the agency responsible for the care of mentally

retarded children and adults.

¶57 This court in Grell I acknowledged that A.R.S. § 13-

703.02 should be applied to the hearing on remand only “insofar

as is practical.” The trial court reasonably concluded that it

was not practicable to apply the statute on this issue. The

State hired Dr. Scialli before it could possibly have known the

yet-unpassed statute’s requirements for qualifications of

experts. In addition, Dr. Scialli appears to be qualified to

diagnose and discuss retardation issues. Indeed, the defense

relies on his testimony to support its own points about the

diagnosis of retardation. And precluding Dr. Scialli’s

testimony would have left the State without an expert on mental

retardation. His qualifications in this instance bear on the

weight of his testimony, not its admissibility. The court did

not abuse its discretion by allowing Dr. Scialli to testify.

D. Error in Finding that Grell Did Not Prove Mental
Retardation

¶58 The defense asserts that the trial court erred in
- 33 -
concluding that Grell does not have mental retardation and

requests that we review that ruling. The decision was based

largely on expert testimony; the trial court determined that the

State’s expert was more credible. “The trial judge has broad

discretion in determining the weight and credibility given to

mental health evidence.” State v. Doerr, 193 Ariz. 56, 69,

¶ 64, 969 P.2d 1168, 1181 (1998). “We defer to the trial

court’s factual findings that are supported by the record and

not clearly erroneous.” State v. Rosengren, 199 Ariz. 112, 116,

¶ 9, 14 P.3d 303, 307 (App. 2000).

¶59 Because the parties stipulated that Grell had a low IQ

before age eighteen, the only issue in the hearing on remand was

his adaptive functioning. Under Arizona law, the adaptive

functioning component of a mental retardation diagnosis requires

“significant impairment” in “the effectiveness or degree to

which the defendant meets the standards of personal independence

and social responsibility expected of the defendant’s age and

cultural group.” A.R.S. § 13-703.02(K)(1), (K)(2).

¶60 Defense counsel relied primarily on school and

juvenile detention records to highlight examples of poor

academic and social behavior. He argued that school and

detention workers did not diagnose students based on the DSM-

- 34 -
IV,12 and thus the fact that no one had diagnosed Grell as having

mental retardation did not establish the absence of that

condition. He urged the court to find deficits in the areas

listed in the DSM-IV.

¶61 The State countered with three main themes: no doctor

before defense expert Dr. Globus had ever diagnosed Grell as

having mental retardation; behaving badly does not necessarily

indicate adaptive deficits; and Grell can behave himself when he

wants to do so. The State relied on the Vineland Scale as the

only test administered to Grell as a youth that would reveal

retardation. The score on that scale was low-average, assessing

his intelligence as being only a year younger than his

chronological age at the time. After moving to Arizona, five

psychiatric reports all showed Grell to have a personality or

conduct disorder, but none indicated mental retardation.

Several school documents literally say that Grell demonstrated

“good adaptive skills.” The State also highlighted a ruse Grell

concocted about his life following an arrest for robbery in

1996. Although he was twenty at the time, Grell claimed to be a

juvenile named Michael Prentice and described a background

12
The DSM-IV instructs that poor adaptive skills exist when
there are deficits in at least two of the following areas:
communication, self-care, home living, social/interpersonal
skills, use of community resources, self-direction, functional
academic skills, work, leisure, health, and safety.
- 35 -
different from his own in a number of respects. Grell

maintained the ruse for more than six months through repeated

contacts with the justice system.

¶62 The defense claims to have clearly shown that Grell

has deficits in two of the eleven areas listed in the DSM-IV and

therefore has mental retardation. The DSM-IV definition of

mental retardation, however, while similar in overall meaning,

is not the same as the statutory definition. See A.R.S. § 13-

703.02(K). The statute requires an overall assessment of the

defendant’s ability to meet society’s expectations of him. It

does not require a finding of mental retardation based solely on

proof of specific deficits or deficits in only two areas.

¶63 Reasonable minds may differ as to how to interpret the

evidence presented. The evidence does, however, support a

finding that Grell was able to function at a level higher than

that of “significant impairment.” The trial judge’s conclusion

was reasonably supported by evidence. The trial court did not

clearly err in finding that Grell failed to prove mental

retardation by clear and convincing evidence.

E. Entitlement to Jury Sentencing

¶64 Grell argues that he is entitled to jury sentencing by

the terms of his trial-by-submission agreement. He asserts that

he “agreed to a trial by submission in exchange for preserving

- 36 -
his claim that the United States Constitution entitled him to a

jury determination of aggravation or mitigation at the

sentencing phase.” The cover statement of the stipulation

states: “This stipulation shall in no way constitute a waiver

of any rights the defendant may have to have a jury empanelled

to determine the existence or absence of any aggravating and or

mitigating circumstances.”

¶65 The State acknowledges that Grell attempted to

preserve his right to a jury trial for sentencing. It argues,

however, that Grell preserved only any “right [he] may have” to

a jury sentencing, not an absolute right to such a proceeding.

Under Ring, the State thus maintains, Grell has a right to a

jury sentencing only if the judicial sentencing was not harmless

error.

¶66 While that may be one way to interpret the jury

sentencing provision, Grell clearly believed that the

stipulation would entitle him to a jury trial on aggravating

facts if the Ring challenge was successful. When the parties

signed the agreement in September 2000, Apprendi had just been

decided. Its reasoning suggested that Arizona’s judge-

sentencing system was unconstitutional. Grell’s stipulation was

thus not a meaningless reservation of a pipe-dream right.

Moreover, because Grell admitted the act of killing his

- 37 -
daughter, the sentencing hearing held increased significance as

his only chance to avoid a sentence of death. He waived his

right to a jury trial on the guilt-phase issues at least in part

based on assurances that he would retain his right to be

sentenced by a jury.

¶67 We find that the agreement entitles Grell to a jury

sentencing. We therefore vacate the sentence of death and

remand for a sentencing proceeding in accordance with A.R.S. §§

13-703 and 13-703.01 (Supp. 2002).

F. Other Issues

¶68 Grell raised several other issues, all of which are

rendered moot by the remand for resentencing. We therefore

decline to address them.

III. CONCLUSION

¶69 We affirm the trial court’s determination that Grell

does not have mental retardation. Because we conclude that the

State is bound by its agreement to afford a jury trial on

sentencing, we vacate Grell’s death sentence and remand the case

for resentencing in accordance with A.R.S. §§ 13-703 and 13-

703.01.

_______________________________________
Rebecca White Berch, Vice Chief Justice

- 38 -
CONCURRING:

_______________________________________
Ruth V. McGregor, Chief Justice

_______________________________________
Michael D. Ryan, Justice

_______________________________________
Sheldon H. Weisberg, Judge*

*Pursuant to Article 6, Section 3 of the Arizona Constitution,
the Honorable Sheldon H. Weisberg, Chief Judge of the Arizona
Court of Appeals, Division One, was designated to sit in this
matter.

B A L E S, Justice, concurring in part and dissenting in part

¶70 Based on the Supreme Court’s decisions in Atkins and

Cooper, I do not believe that the federal constitution allows

states to execute defendants who are more likely than not

mentally retarded but who cannot prove their retardation by the

higher standard of clear and convincing evidence. Accordingly,

I respectfully dissent from my colleagues’ decision to uphold

the clear and convincing standard contained in A.R.S. § 13-

703.02(G).

¶71 “[D]eath is not a suitable punishment for a mentally

retarded criminal.” Atkins, 536 U.S. at 321. Although Atkins
- 39 -
allows states to develop appropriate ways to enforce this

constitutional restriction, id. at 317, the procedures adopted

must themselves pass constitutional muster. Cooper outlines the

proper framework for determining if a statutorily-assigned

standard of proof on the issue of mental retardation comports

with due process.

¶72 The majority recognizes that, while the right not to

be executed if mentally retarded is of “recent vintage,” both

this right (Atkins) and the right not to stand trial if

incompetent (Cooper) are “constitutional right[s] based on

modern consensus and historical views” of the issues. Op. ¶ 32;

accord Pruitt v. State, 834 N.E.2d 90, 100-03 (Ind. 2005)

(noting that the Supreme Court has identified the right of

mentally retarded defendants not to be executed as grounded in a

fundamental principle of justice). I agree with the majority

that, just as states may place on defendants the burden of

proving competency, states may place on defendants the burden of

proving mental retardation. Op. ¶ 29.

¶73 My disagreement with the majority concerns the

standard, rather than the burden, of proof. In arguing for a

clear and convincing standard, the majority notes that there are

“significant differences” between the right of the incompetent

not to be tried and the right of the retarded not to be

- 40 -
executed. Id. ¶ 38. Noting differences in these constitutional

rights does not itself justify requiring defendants to prove

retardation by the higher standard of proof; nor does it

substitute for actually applying the Cooper analysis. Moreover,

the difference between a defendant who might be executed if a

court incorrectly rejects a claim of mental retardation and an

incompetent defendant who might erroneously be subjected to a

trial does not support imposing a higher standard on the former

as compared to the latter.

¶74 Nor can the majority justify a higher standard of

proof by comparing the rights of the retarded and the mentally

insane. Id. ¶ 40. The standard of proof arguably should be

higher for eve-of-execution claims of insanity by defendants who

were competent to be tried and sentenced to death as compared to

defendants who claim to be mentally retarded, a permanent

condition which must be established by evidence of onset before

age eighteen. Cf. Ford v. Wainwright, 477 U.S. 399, 426 (1986)

(Powell, J., concurring) (noting state may presume defendant

remains sane and require defendant to make substantial threshold

showing to obtain hearing on post-sentencing claim of insanity).

Moreover, since Cooper, neither the Supreme Court nor this court

has addressed whether a state can, consistent with the

constitution, execute a person who is more likely than not

- 41 -
insane. Thus, the fact that Arizona statutes require defendants

to establish mental incompetence (i.e., insanity) by clear and

convincing evidence as a bar to execution, see A.R.S. § 13-

4022(F), does not resolve whether the higher standard can

constitutionally apply to that issue or to the issue of mental

retardation.13

¶75 Our legislature enacted A.R.S. § 13-703.02 before

Atkins held that executing a mentally retarded defendant

violates the Eighth Amendment’s prohibition against cruel and

unusual punishment, 536 U.S. at 316, 321. Thus, A.R.S. § 13-

703.02 does not reflect a legislative effort to adopt a statute

in light of the constitutional prohibition. Since Atkins, as

the majority acknowledges, all but one of those states that have

13
The majority notes that the Georgia Supreme Court has
upheld a standard of proof beyond a reasonable doubt for
defendants claiming to be mentally retarded. Op. ¶ 34 n.9. The
Georgia statutory scheme, which allows a verdict of “guilty but
mentally retarded” in felony cases, substantially differs from
Arizona’s capital sentencing scheme, as the majority
acknowledges. Id. Moreover, the Georgia decisions are not
persuasive on the issue presented here. In Head v. Hill, 587
S.E.2d 613, 621 (Ga. 2003), the court reasoned that if a
defendant may be required to prove insanity beyond a reasonable
doubt, see Leland v. Oregon, 343 U.S. 790 (1952), then requiring
proof of mental retardation beyond a reasonable doubt is also
constitutional. This reasoning, however, fails to recognize
that, under Atkins, the mentally retarded have a constitutional
right not to be executed. Whether the State may assign to the
defendant a higher standard for proving non-constitutional
defenses at trial does not address whether the State can execute
defendants who prove they are more likely than not mentally
retarded.
- 42 -
set the standard of proof for proving mental retardation have

adopted a preponderance standard. Op. ¶ 32.

¶76 The majority, however, discounts the significance of

the standard of proof by arguing that, because Arizona’s

statutes provide for a pretrial determination of mental

retardation, “the defendant’s risk . . . is not death, but a

capital trial.” Id. ¶ 35. The majority further states that the

ability of defendants to present mental retardation evidence as

mitigation during the sentencing hearing reduces “the ultimate

risk they face from an adverse determination” under the clear

and convincing standard for the pretrial hearing. Id.

¶77 The flaw in this analysis is that the pretrial hearing

under A.R.S. § 13-703.02 is the defendant’s only opportunity to

secure his constitutional rights under Atkins. See id. ¶ 48

(“The judge hears mental retardation evidence as a legal bar to

execution and the jury hears it for mitigation purposes.”); cf.

id. ¶ 31 (recognizing that the competency hearing provides

“those defendants’ only opportunity to contest competency”).

Under our statutes, the jury does not decide the Atkins issue

when it makes its sentencing determination. See id. ¶ 48.

Instead, each juror makes his or her own decision whether the

defendant has proven any mitigating facts and how such facts

should be valued. A.R.S. § 13-703(C); State ex rel. Thomas v.

- 43 -
Granville, 211 Ariz. 468, ___ ¶ 12 n.3, 123 P.3d 662, 665 n.3

(2005).14

¶78 Mitigation does not go to the constitutional issue in

Atkins. Even before Atkins, a defendant could argue mental

retardation as relevant mitigation evidence. Penry v. Lynaugh,

492 U.S. 302, 319-20 (1989) (holding that, although the

constitution did not prohibit execution of mentally retarded

defendants, the defendant must be allowed to present mental

retardation as mitigation evidence); see also A.R.S. § 13-

703(G). Atkins, however, made clear that the ability to argue

mitigation is not sufficient to avoid the constitutional issue

as “[m]entally retarded defendants in the aggregate face a

special risk of wrongful execution.” 536 U.S. at 321

(abrogating Penry, 492 U.S. at 323-25).15

14
Cf. Johnson v. State, 102 S.W.3d 535, 541 (Mo. 2003)
(“[T]he jury was not faced with the Atkins pronouncement: ‘death
is not a suitable punishment for a mentally retarded criminal.’
Rather, the jury instructions treated mental retardation as a
mere mitigating circumstance—not the outright bar to punishment
dictated by Atkins.”); Kristen F. Grunewald, Case Notes, Atkins
v. Virginia, 122 S. Ct. 2242, 15 Cap. Def. J. 117, 125 (2002)
(“In Atkins, mental retardation acts as a bar to death. In
mitigation, mental retardation is a reason to show mercy.”).
15
This court recognized the substantial difference between
considering mental retardation as a possible mitigating factor
and treating it as an absolute bar to the death penalty when the
court remanded this case for reconsideration in light of Atkins
after the trial judge had rejected Grell’s claim of mental
retardation as a mitigating factor. See State v. Grell, 205
Ariz. 57, 63, ¶¶ 37-40, 66 P.3d 1234, 1240 (2003).
- 44 -
¶79 Although one or more jurors may find that the

defendant has proven mental retardation by a preponderance of

the evidence, the jurors remain free to decide that such

evidence is not sufficiently substantial to call for leniency

and to impose a death sentence. See A.R.S. § 13-703(C);

Granville, 211 Ariz. at ___ ¶ 12 n.3, 123 P.3d at 665 n.3.

Indeed, as the Supreme Court noted in Atkins, reliance on mental

retardation as a mitigating factor can be a “two-edged sword”

because the jury may consider the same evidence as supporting

the imposition of a death sentence. 536 U.S. at 321 (noting

that mental retardation may enhance likelihood of finding of

aggravating factor of future dangerousness). We cannot uphold a

clear and convincing standard by relying on the very process the

Atkins court determined was insufficient to protect the

constitutional rights of the mentally retarded.

¶80 In addition, the majority reasons that a clear and

convincing standard is constitutional because Atkins recognized

that, while there is national consensus against executing the

mentally retarded, “people may disagree over which individuals

in fact have mental retardation.” Op. ¶ 37. States must

protect those defendants who fall within the national consensus

on mental retardation, but “are otherwise free to craft their

laws for determining which defendants meet the consensus

- 45 -
standard.” Id. But the fact that the Court has afforded states

some flexibility in substantively defining mental retardation in

no way answers whether states may constitutionally execute those

defendants who prove they are more likely than not retarded

under any applicable definition.

¶81 The majority attempts to argue that A.R.S. § 13-703.02

protects those defendants who fall within the national consensus

by providing them with “a comparatively lower bar” while

requiring defendants with higher IQ scores to “go to greater

lengths to prove their mental retardation.” Id. This argument

mistakenly assumes the “national consensus” embraces only

defendants whose IQs are 65 or below and it fails to recognize

how the statute actually works even as to those defendants.

Although A.R.S. § 13-703.02 creates a rebuttable presumption of

mental retardation for defendants whose IQ scores are 65 or

below, this presumption shifts only the burden of production,

not the burden of persuasion, to the State. State v. Arellano,

___ Ariz. ___, ___ ¶¶ 11-12, ___, P.3d ___, ___ (2006). Once

the State has come forth with any evidence to rebut the

presumption, the defendant still must prove mental retardation

by clear and convincing evidence, regardless of IQ scores.

¶82 Additionally, the majority dismisses the “special risk

of wrongful execution” faced by mentally retarded defendants by

- 46 -
stating “it does not suggest the need for any particular

procedure to ascertain mental retardation.” Op. ¶ 36. The

majority asserts that the clear and convincing standard will

assure that “defendants about whom there is a consensus against

execution will be screened out at the pretrial stage”; other

defendants do not “face such a severe risk at sentencing that

they may not constitutionally be put through the capital trial

process.” Id.

¶83 The right of the mentally retarded not to be executed,

however, is not limited to those defendants who are severely

retarded or who otherwise can establish their condition by

especially compelling evidence.16 Under Atkins, the Eighth

Amendment prohibits the execution of all mentally retarded

defendants. See id. ¶ 37 (“[T]he Court in Atkins clearly

announced that states may not execute the mentally

retarded . . . .”). Defendants who can prove their mental

retardation by only a preponderance will not be “screened out”;

as a result, they still face the same special risk that,

according to Atkins, cannot be remedied during mitigation. 536

16
Indeed, the defendant in Atkins claimed to be “mildly
mentally retarded,” 536 U.S. at 308, and our statute includes
mildly mentally retarded defendants, A.R.S. § 13-703.02(K)(4).
See also Atkins, 536 U.S. at 308 n.3 (noting that “mild” mental
retardation is typically used to describe people with an IQ
level of 50-55 to approximately 70) (citing Diagnostic and
Statistical Manual of Mental Disorders 42-43 (4th ed. 2000)).
- 47 -
U.S. at 320-21.

¶84 Thus, the real issue here, which the majority does not

directly confront, is whether the State can constitutionally

execute those defendants who prove they are more likely than not

mentally retarded but cannot meet the clear and convincing

standard under A.R.S. § 13-703.02(G).

¶85 The Supreme Court in Cooper applied due process

principles to assess a state’s imposing a clear and convincing

standard of proof on a criminal defendant. Although Cooper

dealt with the constitutional right not to stand trial if

incompetent, its framework applies in evaluating the standard of

proof on mental retardation. See Pruitt, 834 N.E.2d at 100-03

(applying Cooper to mental retardation issue); State v.

Williams, 831 So. 2d 835, 859-60 (La. 2002) (same); Howell v.

State, 151 S.W.3d 450, 463-65 (Tenn. 2004) (same); see also

Bowling v. Commonwealth, 163 S.W.3d 361, 382 (Ky. 2005) (citing

Cooper and applying preponderance of the evidence standard as

“[w]e have applied . . . to a defendant’s burden to prove

incompetency to stand trial”).

¶86 In Cooper, the Court noted that historic and

contemporary standards support a fundamental right not to stand

trial if incompetent; in Atkins, the Court recognized a similar

right not to be executed if mentally retarded. Op. ¶ 32. The

- 48 -
Cooper court also noted that most jurisdictions required a

preponderance of the evidence or less to show incompetency;

similarly, most jurisdictions require only a preponderance of

the evidence for a showing of mental retardation. Id. & n.7.

¶87 Given the constitutional right at issue, the Court in

Cooper weighed the respective interests of the state and the

defendant to assess the fundamental fairness of requiring the

defendant to prove incompetency by clear and convincing

evidence. 517 U.S. at 362-67. “The function of a standard of

proof . . . is to instruct the factfinder concerning the degree

of confidence our society thinks he should have in the

correctness of factual conclusions . . . .” Id. at 362

(quotation marks and citation omitted). “The more stringent the

burden of proof a party must bear, the more that party bears the

risk of an erroneous decision.” Id. (quotation marks and

citation omitted).

¶88 The Cooper court determined that the “consequences of

an erroneous determination of competence are dire” for the

defendant because he would not be able to communicate with his

attorney or exercise other fundamental rights involved in a fair

trial. Id. at 364. In contrast, the injury to the state from

an erroneous conclusion that a defendant is incompetent when he

in fact is malingering is “modest.” Id. at 365. The state may

- 49 -
incur expense and delay, but such errors are subject to

correction in subsequent proceedings and the state may detain

the defendant for a reasonable time to determine if he might

later become competent. Id. Recognizing that there were

important state interests at stake, the Court concluded that,

where incompetence is shown by a preponderance of the evidence,

“the defendant’s fundamental right to be tried only while

competent outweighs the [s]tate’s interest in the efficient

operation of its criminal justice system.” Id. at 367.

¶89 Applying Cooper’s weighing of interests framework

here, the use of a clear and convincing evidence standard “would

significantly increase the risk of an erroneous determination”

of no mental retardation for defendants who can prove they are

more likely than not mentally retarded. Williams, 831 So. 2d at

860 (citing Cooper, 517 U.S. at 362-63). The imposition of the

death penalty is serious and permanent; any mistake cannot be

undone once the punishment is carried out. See Evans v. State,

886 A.2d 562, 584 (Md. 2005) (“Reflected throughout the Supreme

Court jurisprudence underlying the Eighth Amendment is the

principle that death is different.”).

¶90 The State’s interest, in contrast, is at best modest,

likely even less than the interest involved in Cooper. See

Howell, 151 S.W.3d at 465 (“[T]he risk to the petitioner of an

- 50 -
erroneous outcome is dire, as he would face the death penalty,

while the risk to the State is comparatively modest.”) (citing

Cooper, 517 U.S. at 364-65). At oral argument, counsel for the

State candidly acknowledged that the State does not have any

“particular interest” in executing those defendants who can

establish their mental retardation by a preponderance but not by

clear and convincing evidence. To be sure, the State does have

an interest in preventing malingering defendants from obtaining

erroneous determinations of their mental retardation. But such

determinations do not, in contrast to the competency

determinations involved in Cooper, prevent the State from

concluding criminal proceedings against the defendant; they

instead limit the ultimate punishment the State can exact.

Additionally, the risks of malingering are reduced because the

statutory definition of mental retardation requires proof not

only of a low IQ but also significantly impaired adaptive

behavior and the onset of such conditions before the age of

eighteen. A.R.S. § 13-703.02(K)(2).

¶91 When the relative risks are death and a lesser

available punishment, “the defendant’s right not to be executed

if mentally retarded outweighs the state’s interest as a matter

of federal constitutional law.” Pruitt, 834 N.E.2d at 103;

accord Williams, 831 So. 2d at 860 (“Clearly, in the Atkins

- 51 -
context, the State may bear the consequences of an erroneous

determination that the defendant is mentally retarded (life

imprisonment at hard labor) far more readily than the defendant

of an erroneous determination that he is not mentally

retarded.”); Howell, 151 S.W.3d at 465 (“The balance, under

these circumstances, weighs in favor of the petitioner and

justifies applying a preponderance of evidence standard at the

hearing.”).

¶92 In light of the interests involved, I would hold that

the clear and convincing standard of proof under A.R.S. § 13-

703.02(G) is unconstitutional because the State cannot,

consistent with due process, execute those defendants who show

they are more likely than not mentally retarded. Thus, on

remand, the trial court should consider whether Grell can

establish mental retardation by a preponderance of the evidence

before the court conducts further sentencing proceedings before

a jury. I otherwise concur in the majority’s opinion.

_______________________________________
W. Scott Bales, Justice

- 52 -

OPINION

BERCH, Vice Chief Justice.
¶ 1 Appellant Shawn Grell was convicted of first degree murder in 2000 following a bench trial on stipulated facts. After an aggravation and mitigation hearing, the judge sentenced Grell to death. While Grell prepared his direct appeal, the United States Supreme Court decided eases that held (1) that juries must find the aggravating factors that allow the imposition of a sentence of death, Ring v. Arizona (Ring II), 536 U.S. 584, 122 S.Ct. 2428, 153 L.Ed.2d 556 (2002), and (2) that mentally retarded defendants may not be executed, Atkins v. Virginia, 536 U.S. 304, 122 S.Ct. 2242, 153 L.Ed.2d 335 (2002). In addition to raising sentencing issues under Ring, Grell claimed on appeal that, under Atkins, his mental retardation should preclude a death sentence in his case. In lieu of reviewing Grell’s sentence for harmless error, this court ordered the trial court to reexamine the issue of Grell’s mental retardation, applying the standards articulated in Atkins. State v. Grell (Grell I), 205 Ariz. 57, 63, ¶ 41, 66 P.3d 1234, 1240 (2003). On February 2, 2005, the trial court held another hearing and issued its ruling finding no mental retardation.

¶ 2 For the appeal, this court ordered the parties to combine briefings on both the sentencing issues and the mental retardation issues. We have jurisdiction under Article 6, Section 5(3) of the Arizona Constitution and Arizona Revised Statutes (“A.R.S.”) section 13-4031 (2001). We affirm the trial court’s finding that Grell did not prove mental retardation, but remand the case for jury sentencing.

I. FACTS1

¶ 3 On December 2, 1999, Shawn Grell picked up his two-year-old daughter, Kristen, from daycare. They drove around for several hours, during which time Grell bought a plastic gas can and gasoline. He then drove to a deserted area in Mesa, put his sleeping daughter on the ground, poured gasoline on her, and lit her on fire. She awoke and stumbled several feet while engulfed in flames before eventually succumbing to the smoke and flames. Grell drove to a nearby convenience store to buy beer. He told the clerk he had seen some kids set a dog on fire in a vacant lot. After driving around for several hours, Grell called the police and turned himself in at five o’clock the next morning. He later held a press conference at which he admitted killing his daughter.

¶4 Grell was charged with first degree murder and child abuse. He waived a jury trial and instead the parties submitted to the trial judge a twenty-page narrative with forty-four attachments to serve as a basis for determining guilt. In September 2000, the judge convicted Grell of first degree murder, but acquitted him of child abuse.

¶ 5 Grell agreed to the admission of the documents at the sentencing hearing, but attempted to preserve his right to a jury trial on sentencing issues by the following language: “This stipulation shall in no way constitute a waiver of any rights the defendant may have to have a jury empanelled to determine the existence or absence of any aggravating and or mitigating circumstances.” When Grell specifically requested that a jury be empanelled for the sentencing proceeding, however, the motion was denied.

A. Original Sentencing

¶ 6 The combined aggravation and penalty phase hearing held in June 2001 included testimony from mental health experts, law enforcement officers, a burn injury expert, *519and Grell’s sister. The State asserted three statutory aggravating factors: that Grell had previously been convicted of a serious offense; that the crime was committed in an especially heinous, cruel, or depraved manner; and that the victim was younger than fifteen years of age. See A.R.S. § 13-703(F)(2), (F)(6), (F)(9) (1999). The trial court found all three.

¶ 7 The prior serious offense was a 1996 conviction for robbery. See A.R.S. § 13-703(H) (1999) (identifying robbery as a “serious offense” for purposes of use as a death penalty aggravator). That Kristen was younger than fifteen at the time of the crime was proven by a birth certificate showing her 1997 birthdate, which established that she was two years old at the time of her death.

¶8 Citing the facts that Kristen was conscious when set on fire, that she had to have suffered immense physical pain, and that Grell should have foreseen the pain she would suffer, the court also found the crime “especially cruel.” In addition, while acknowledging that only a finding of cruelty was necessary to satisfy the § 13-703(F)(6) aggravating factor, the court also found the crime heinous and depraved.2 The court cited the following factors in making these findings: (1) the crime was senseless; (2) the victim was helpless; (3) the victim was the defendant’s own child; (4) the method of killing ensured that the victim would suffer “unimaginable pain”; (5) the method ensured that the body would be disfigured; and (6) the defendant made comments to a convenience store clerk after the murder about seeing a dog set on fire.3 The court stated that these facts satisfied the test set forth in State v. Gretzler, 135 Ariz. 42, 659 P.2d 1 (1983), and concluded that the manner of killing, in addition to being cruel, was also heinous and depraved.

¶ 9 In mitigation, Grell alleged the statutory mitigating circumstance of mental impairment, see A.R.S. § 13 — 703(G)(1), as well as non-statutory mitigators of mental retardation, learning disabilities, difficult childhood, and remorse. Much of the evidence at the hearing centered on Grell’s claims of mental impairment, mental retardation, and a cognitive disorder caused by brain damage.

¶ 10 Drs. Globus and Wicks testified for the defense and Drs. Mayberg and Scialli testified for the State. On the issues of mental impairment and brain damage, Dr. Globus testified that he initially diagnosed Grell with brain damage before having a PET scan done and before having Dr. Wicks do a blind neuropsychological evaluation of Grell. Dr. Globus is not certified to read PET scans, and those who prepared the report for him did not testify, facts noted by the court in its sentencing decision. Dr. Mayberg, the State’s neuropsychologist who is qualified to read PET scans, testified that Grell’s PET scan showed no brain damage. Dr. Scialli testified that he found no evidence of a cognitive disorder caused by brain damage, but instead diagnosed Grell as having only an anti-social personality disorder.

¶ 11 The trial court ultimately found “no credible evidence” that Grell suffered from brain damage. The court instead accepted Dr. Scialli’s diagnosis that Grell suffered from an anti-social personality disorder, symptoms of which include acting impulsively and using poor judgment.

¶ 12 Drs. Globus and Wicks also testified regarding Grell’s mental retardation, as did Dr. Scialli. The court acknowledged Grell’s low IQ scores, ranging from 65 to 74, but weighted more heavily Dr. Scialli’s testimony that Grell had adequate adaptive skills.4 In *520addition, the trial court observed that no one before Drs. Globus and Wicks had ever diagnosed Grell as having mental retardation and that Grell had demonstrated good adaptive skills by maintaining a false identity in order to be charged as a juvenile after he was arrested for robbery in 1996 when he was twenty years old.

¶ 13 Finding no mitigation sufficiently substantial to call for leniency, the judge sentenced Grell to death.

B. First Appeal

¶ 14 An automatic notice of appeal was filed. While the parties prepared for oral arguments, the United States Supreme Court handed down opinions in Atkins, 536 U.S. at 304, 122 S.Ct. 2242, and Ring II, 536 U.S. at 584, 122 S.Ct. 2428. This case was consolidated with other capital cases pending on direct appeal at the time for the purpose of deciding common Ring issues. State v. Ring (Ring III), 204 Ariz. 534, 65 P.3d 915 (2003). This court issued a decision in Grell I without considering the sentencing issues. 205 Ariz. at 60, ¶ 25, 66 P.3d at 1237.

¶ 15 In Grell I, 205 Ariz. at 58, ¶ 2, 66 P.3d at 1235, this court addressed Grell’s trial issue and affirmed his conviction, but remanded the matter to the trial court for a reevaluation of Grell’s mental retardation claim in light of Atkins. The trial court had evaluated the mental retardation evidence as a mitigating factor rather than as a complete bar to execution. This court suggested that, on remand, the trial judge should apply A.R.S. § 13-703.02 as a guide in future proceedings to ascertain the existence of mental retardation.5 Id. at 64, ¶ 42, 66 P.3d at 1241.

C. Remand for Mental Retardation Hearing

¶ 16 Attempting to follow the procedures in A.R.S. § 13-703.02, the trial judge first suggested appointing a “pre-screening expert” to test Grell’s IQ. Rather than subjecting Grell to additional testing, the State and the defense stipulated that Grell’s IQ was less than 70 and that further IQ testing was unnecessary.

¶ 17 Before the mental retardation hearing, the parties briefed and argued the issue of burden of proof. The statute places the burden on the defendant to prove mental retardation by clear and convincing evidence. A.R.S. § 13-703.02(G). Grell argued, however, that because mental retardation serves as a constitutional bar to execution, the standard should be no higher than a preponderance of the evidence. Rejecting Grell’s claim, the trial court required Grell to prove mental retardation by clear and convincing evidence.

¶ 18 During preparations for the hearing on remand, a new defense expert, Dr. Denis W. Keyes, interviewed Grell. The State requested that Grell also submit to examination by its new expert, Dr. Dan Martel. Before Dr. Keyes completed his report and before meeting with Dr. Martel, Grell told his attorneys he was “not willing to cooperate any further with any of our experts or investigators.” Shortly thereafter, Dr. Keyes completed his report, which concludes that Grell has mental retardation.

¶ 19 After receiving Grell’s written refusal to be examined, the State moved to “Pre*521elude Defendant’s Additional Mental Health Professional.” The defense, which did not yet have Dr. Keyes’ report, did not respond to the motion. As a result of these circumstances, the trial court granted the State’s motion to preclude Dr. Keyes from testifying. After receiving Dr. Keyes’ report, the defense filed a Motion to Reconsider, which was denied.

¶ 20 Following the motion and Grell’s refusal to cooperate, each side determined that it had no additional evidence to present and would rely on the evidence presented at the June 2001 hearing. The court held oral argument on December 7, 2004, at which each side argued from the same documents and the same testimony to the same judge as in the first hearing. Quoting extensively from the record and noting that it had previously found the State’s experts more persuasive, the trial court found nothing “to change its mind” and concluded that Grell had failed to satisfy his burden of proving mental retardation by clear and convincing evidence.

II. Discussion

A. The Burden of Proof and Standard for Proving Mental Retardation

¶ 21 Grell’s major argument on this appeal is that the trial court used a flawed process in finding that he does not have mental retardation. He raises three challenges to the process: First, the State should bear the burden of proving lack of retardation to a jury beyond a reasonable doubt. Second, if the defendant must bear the burden of proof, the standard should be no higher than a preponderance of the evidence; the statutory requirement of clear and convincing evidence is unconstitutionally high. Third, the process should be bifurcated, with both a pretrial hearing before a judge to determine, under Atkins, whether mental retardation should bar the defendant’s execution and, should the judge not find mental retardation, a jury component in which the jury must find, beyond a reasonable doubt, that the defendant does not have mental retardation.6

¶22 Grell’s challenges raise issues of constitutional law and statutory construction, which we review de novo. State v. Moody, 208 Ariz. 424, 445, ¶ 62, 94 P.3d 1119, 1140 (2004). In analyzing statutes, however, we begin by assuming the statute is constitutional. State v. Casey, 205 Ariz. 359, 362, ¶ 11, 71 P.3d 351, 354 (2003).

1. Imposing burden on defendant to prove mental retardation

¶23 For the hearing to determine whether Grell has mental retardation, this court instructed the trial court to apply the procedures in A.R.S. § 13-703.02 “insofar as is practical in the post-trial posture of this case.” Grell I, 205 Ariz. at 64, ¶ 42, 66 P.3d at 1241. The statute places on “the defendant ... the burden of proving mental retardation by clear and convincing evidence” in the pretrial hearing. A.R.S. § 13-703.02(G). If the defendant’s IQ is 65 or lower, a rebut-table presumption of mental retardation arises. Id. Because the parties here stipulated that Grell’s IQ falls between 65 and 70, the trial court accordingly placed the burden on him to prove by clear and convincing evidence that mental retardation renders him ineligible for execution. Grell argues that if the defendant must bear the burden at all, the standard should be to prove retardation by no more than a preponderance of the evidence.

¶24 This issue reaches our court because in Atkins, the Supreme Court declined to specify the procedures that states should use to identify mentally retarded individuals, deferring to the states to develop appropriate procedures. Atkins, 536 U.S. at 317, 122 S.Ct. 2242. The Court did so in part in acknowledgement of the lack of consensus regarding which defendants have mental retardation:

To the extent there is serious disagreement about the execution of mentally retarded offenders, it is in determining which offenders are in fact retarded____Not all people who claim to be mentally retarded will be so impaired as to fall within the range of mentally retarded offenders about *522whom there is a national consensus. As was our approach in Ford v. Wainwright, 477 U.S. 399, 106 S.Ct. 2595, 91 L.Ed.2d 335 (1986), with regard to insanity, “we leave to the State[s] the task of developing appropriate ways to enforce the constitutional restriction upon [their] execution of sentences.” Id. at 405, 416-417, 477 U.S. 399,106 S.Ct. 2595, 91 L.Ed.2d 335.

Atkins, 536 U.S. at 317, 122 S.Ct. 2242. Although left to the states, the procedures developed must comport with the Constitution.

¶25 The Supreme Court has confirmed that states may “ ‘regulate the procedures under which [their] laws are carried out, including the burden of producing evidence and the burden of persuasion,’ and [their] decision[s] in this regard [are] not subject to proscription under the Due Process Clause unless ‘[they] offend[ ] some principle of justice so rooted in the traditions and conscience of our people as to be ranked fundamental’ ” Patterson v. New York, 432 U.S. 197, 201-02, 97 S.Ct. 2319, 53 L.Ed.2d 281 (1977) (quoting Speiser v. Randall, 357 U.S. 513, 523, 78 S.Ct. 1332, 2 L.Ed.2d 1460 (1958)); see also Medina v. California, 505 U.S. 437, 445, 112 S.Ct. 2572, 120 L.Ed.2d 353 (1992) (calling Patterson the “proper analytical approach” in evaluating burdens of proof). Grell claims that imposing the burden on a defendant to prove mental retardation by clear and convincing evidence does offend deeply rooted principles.

¶ 26 Grell initially argues that the burden on the issue of mental retardation should not fall on the defendant at all, but rather should be borne by the State. We disagree that the Constitution requires the prosecution to bear this burden. The Supreme Court has held that a state may require that the defendant prove affirmative defenses. E.g., Patterson, 432 U.S. at 206, 97 S.Ct. 2319 (requiring the defendant to prove extreme emotional disturbance); Martin v. Ohio, 480 U.S. 228, 236, 107 S.Ct. 1098, 94 L.Ed.2d 267 (1987) (requiring the defendant to prove self defense). Proof of mental retardation is like proof of an affirmative defense in that it serves to relieve or mitigate a defendant’s criminal responsibility, and as with affirmative defenses, the evidence of retardation will lie largely within the possession and control of the defendant.

¶27 Because the defendant has superior access to the evidence to prove his mental condition, it is not inappropriate to place the burden on him to do so. See Medina, 505 U.S. at 455, 112 S.Ct. 2572 (O’Connor, J., concurring); cf. Patterson, 432 U.S. at 206, 97 S.Ct. 2319 (to same effect). A critical component of proof of mental retardation is onset before age eighteen. The defendant has better information regarding his condition and superior access to friends and family who knew him before he turned eighteen. Moreover, a defendant has significant motivation to attempt to score poorly on an IQ test, a low score on which triggers a claim of mental retardation. See A.R.S. § 13-703.02(B). Such evidence lies within the defendant’s control and may prove difficult for the state to rebut.

¶28 New Jersey is the only state, as of this writing, to place the burden of disproving mental retardation on the state. State v. Jimenez, 380 N.J.Super. 1, 880 A.2d 468, 484 (2005). It did so because state law developed under the Ring/Apprendi line of cases treats certain statutory “capital triggers” like aggravating factors that the state must prove to a jury beyond a reasonable doubt. Id. at 482-84 (discussing the implications of Ring II, 536 U.S. at 584, 122 S.Ct. 2428, and Apprendi v. New Jersey, 530 U.S. 466, 120 S.Ct. 2348, 147 L.Ed.2d 435 (2000)). The court in Jimenez held that mental retardation was essentially such a “capital trigger,” which under New Jersey law the state must prove beyond a reasonable doubt. 880 A.2d at 484. Because, however, the absence of mental retardation is neither an aggravating factor nor an element of the capital offense under Arizona law, the rationale supporting the result in Jimenez does not apply here.

¶29 We find no constitutional bar to imposing the burden of proving mental retardation on the defendant.

2. Imposition of the “clear and convincing evidence” standard

¶ 30 Citing Cooper v. Oklahoma, 517 U.S. 348, 116 S.Ct. 1373, 134 L.Ed.2d 498 (1996), Grell asserts the unconstitutionality of *523requiring him to prove mental retardation by clear and convincing evidence. In Cooper, the Court, having already declared that the defendant must bear the burden of proving competency to stand trial, id. at 355, 116 S.Ct. 1373, held that the defendant may not be forced to prove his competency by clear and convincing evidence. Id. at 369, 116 S.Ct. 1373. The Court evaluated the right not to be tried while incompetent and weighed the impact of its loss on the defendant to determine the appropriate standard of proof. Id. at 354, 364, 116 S.Ct. 1373. The Court observed that the right not to be tried if incompetent is a fundamental “principle of justice [so] rooted in the traditions and conscience of our people” that its violation “threatens ... the basic fairness of the trial itself.” Id. at 364,116 S.Ct. 1373.

¶ 31 Furthermore, the Court reasoned, the heightened standard of proof affected only those defendants who could prove they were incompetent, but could not do so by clear and convincing evidence. Id. at 366-67, 116 S.Ct. 1373. The higher standard affected those defendants’ only opportunity to contest competency, creating a grave risk of violating their right not to be tried while incompetent. Id. The Court concluded that the defendants’ interest outweighed the government’s lesser interest in trying a probably incompetent defendant. Id. The Court also noted that forty-six other state jurisdictions used a lower standard of proof, showing consensus that Oklahoma’s higher standard was unnecessary to serve the state’s needs and inappropriate in light of the importance of the right. Id. at 361-62, 116 S.Ct. 1373. The Court therefore held that due process limits the burden on the defendant to prove competency to stand trial by a standard no higher than preponderance of the evidence. Id. at 368-69,116 S.Ct. 1373.

¶ 32 As was the Court in Cooper, we have been asked to assess the statutory imposition of a clear and convincing evidence standard in a situation in which a preponderance standard would be permissible. Although the right not to be executed if mentally retarded is of recent vintage, it — like the right not to stand trial if incompetent — is a constitutional right based on modern consensus and historical views regarding the propriety of executing those who may be “less morally culpable” because of their reduced mental capacity. See Atkins, 536 U.S. at 320-21, 122 S.Ct. 2242. We also note that, following Atkins, all but one jurisdiction that has chosen a burden has chosen preponderance of the evidence.7 We might have done so as well, were there no Arizona statute already in place. The question before us, however, is whether the standard chosen by the legislature to protect admittedly important state interests can withstand constitutional scrutiny.

¶ 33 The statutory scheme enacted by the Arizona legislature does not merely prohibit execution of the mentally retarded. It provides a detailed, bifurcated process that requires a pretrial hearing at which a defendant may attempt to show, by clear and convincing evidence, that he has mental retardation; if he fails to make that showing, the defendant may still present mental retardation evidence to the jury in mitigation of his sentence. A.R.S. § 13-703.02. The statutory process gives the defendant with an IQ of 75 or below the opportunity to be examined by at least two psychological experts to *524determine his IQ. A.R.S. § 13-703.02(B), (D). Those with at least one full-scale IQ test result of 70 or below proceed for further evaluation and an evidentiary hearing. A.R.S. § 13-703.02(F), (G). Although the defendant bears the ultimate burden to prove mental retardation, the statute creates a rebuttable presumption of mental retardation if the defendant’s IQ is 65 or below. A.R.S. § 13-703.02(G).8

¶ 34 The Arizona statute sets up a process similar to that used in Colorado and Indiana, and courts in both those states have evaluated the constitutionality of requiring a defendant to prove mental retardation by clear and convincing evidence.9 Compare People v. Vasquez, 84 P.3d 1019 (Colo.2004) (approving use of clear and convincing standard in a pretrial hearing), with Pruitt v. State, 834 N.E.2d 90 (Ind.2005) (finding a clear and convincing standard unconstitutional). Grell and our dissenting colleague rely heavily on analysis from Cooper that also formed the basis of the Pruitt opinion. They argue that the definitive inquiry is the assessment of the relative risks faced by the parties: the defendant’s risk of death compared to the state’s minimal interest in executing a defendant who will otherwise go to prison for life.

¶ 35 With respect to statutes like those in Arizona, Indiana, and Colorado, however, Grell overstates his case. As the Colorado Supreme Court stressed in Vasquez, the defendant’s risk at a pretrial hearing is not death, but a capital trial.10 84 P.3d at 1023. By creating a pretrial process, the legislature provided a way for mentally retarded defendants to avoid the burden of a capital trial and the risk of imposition of the capital penalty. All defendants who do not prove mental retardation at the pretrial hearing retain the ability to present mental retardation evidence to the jury under a preponderance standard in the penalty phase of the trial. That opportunity reduces the ultimate risk they face from an adverse determination in the pretrial mental retardation hearing.

¶ 36 The court in Pruitt acknowledged but rejected the argument that the defendant’s ability to argue mental retardation evidence in mitigation to the jury under a preponderance of the evidence standard adequately safeguards the defendant’s rights. It reasoned that “[mjentally retarded defendants in the aggregate face a special risk of wrongful execution.” 834 N.E.2d at 103 (quoting Atkins, 536 U.S. at 321, 122 S.Ct. 2242). Although the acknowledged risk that the Pruitt court identifies may justify barring the execution of the mentally retarded, it does not suggest the need for any particular procedure to ascertain mental retardation. Under Arizona’s statutory procedure, these defendants about whom there is consensus against execution will be screened out at the pretrial stage. Given that fact, we cannot say that those unable to establish retardation by clear and convincing evidence face such a severe risk at sentencing that they may not constitutionally be put through the capital trial process.

*525¶ 37 Although the Court in Atkins clearly announced that states may not execute the mentally retarded, it recognized that people may disagree over which individuals in fact have mental retardation. 536 U.S. at 317, 122 S.Ct. 2242. Before Atkins, states had already begun to develop their own procedures, and had drawn in different places the line for establishing the mental retardation that would bar execution. Knowing this, the Court explicitly left the procedure for determining mental retardation to the states. Id. State procedures must ensure that those about whom there is national consensus are protected from execution, but left states otherwise free to craft their laws for determining which defendants meet the consensus standard. By providing differing procedures based on the defendant’s IQ, Arizona law reflects this concept. Those with IQ scores of 65 or below face a comparatively lower bar, while those whose IQ scores suggest greater intelligence must go to greater lengths to prove their mental retardation. The legislature placed a heavier burden on those who do not fall within the group about whom there is national consensus regarding their right not to be executed. The procedure occurs early in the capital process and removes defendants found to have mental retardation from exposure to a capital trial and hence to a sentence of death. See A.R.S. § 13-703.02(0), (F), (G). The application of Arizona’s tiered procedure does not deprive Grell of a right rooted in fundamental justice.

¶ 38 Finally, in response to the reliance of the defendant and our dissenting colleague on the analysis in Cooper, 517 U.S. at 348, 116 S.Ct. 1373, we note the significant differences between the right not to be tried while incompetent and the right not to be executed if mentally retarded. First, a defendant found incompetent to stand trial is protected from having to submit to trial on any charges unless he is restored to competency. See id. A defendant deemed to have mental retardation, however, is not shielded from trial. See Atkins, 536 U.S. at 318,122 S.Ct. 2242. Despite the risks that a mentally retarded defendant might not present well to a jury, such a defendant can be tried, found guilty, and sentenced to any statutory criminal penalty other than death. This legal distinction suggests that mental retardation differs constitutionally from incompetence to stand trial.

¶39 The second distinction relates to the risk of malingering. A defendant who successfully feigns incompetence to stand trial will not have to submit to trial at that time. Generally, however, such a defendant is sent to a mental health facility for treatment and further examination of his competency. See Ariz. R.Crim. P. 11.5(b)(2)(i). Most often, the defendant is either restored to competency or discovered to be malingering. In the event of either occurrence, the defendant is subject to trial and punishment, including the death penalty, if appropriate. On the other hand, once a court determines that a defendant has mental retardation, that defendant may never suffer the punishment of execution, even if he is later discovered to have been malingering. These concerns support the heightened standard that the legislature has imposed to protect the interests of Arizona citizens.

¶40 A better comparison lies between claims of mental retardation as a bar to execution and claims of mental incompetence as a bar to execution. The defendant asserting the latter claim is also subject to a clear and convincing evidence burden of proof. See A.R.S. § 13-4022(F) (clear and convincing burden of proof); Ford v. Wainwright, 477 U.S. 399, 410, 106 S.Ct. 2595, 91 L.Ed.2d 335 (1986) (holding that the Eighth Amendment prohibits states from “inflicting the penalty of death upon a prisoner who is insane”). We are aware of no case finding it violative of the Constitution to require a defendant to prove incompetence to be executed by clear and convincing evidence.

¶41 In sum, we conclude that requiring the defendant to prove mental retardation by clear and convincing evidence in the initial retardation hearing does not violate constitutional standards.

3. Jury determination of mental retardation

¶42 Grell argues that, under Ring, the jury must find beyond a reasonable doubt that the defendant does not have mental *526retardation before it may impose a sentence of death. Furthermore, he argues, the process should be bifurcated: a judge should make a preliminary finding on mental retardation, and if the judge finds the defendant death-eligible, the state still must prove a defendant’s lack of mental retardation beyond a reasonable doubt to the jury.

¶ 43 Ring and Apprendi require that a jury find all functional elements of a crime and all non-admitted facts except prior convictions that increase the sentence above the presumptive sentence. See Apprendi, 530 U.S. at 489,120 S.Ct. 2348. Although mental retardation does indeed involve fact-finding, it is not the functional equivalent of an element of the crime. It has nothing to do with the acts that make up the crime itself or the defendant’s mental state while committing the crime, facts the state traditionally must prove. As a result, Ring does not require that a jury find the absence of mental retardation. See Arbelaez v. State, 898 So.2d 25, 43 (Fla.2005); Ex parte Briseno, 135 S.W.3d 1, 10 (Tex.Crim.App.2004); Winston v. Commonwealth, 268 Va. 564, 604 S.E.2d 21, 50 (2004) .

¶44 Nor is the absence of retardation a fact that increases the available penalty. See Apprendi, 530 U.S. at 490 n. 16, 120 S.Ct. 2348; see also United States v. Booker, 543 U.S. 220, 244, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005) . The finding that a defendant does not have mental retardation “neither expos[es] the defendant to a deprivation of liberty greater than that authorized by the verdict according to statute, nor ... impostes] upon the defendant a greater stigma than that accompanying the jury verdict alone.” Bowling v. Commonwealth, 163 S.W.3d 361, 379 (Ky.2005); see also Head v. Hill, 277 Ga. 255, 587 S.E.2d 613, 619-20 (2003); Russell v. State, 849 So.2d 95, 147-48 (Miss.2003); State v. Flores, 135 N.M. 759, 93 P.3d 1264, 1267 (2004); State v. Laney, 367 S.C. 639, 627 S.E.2d 726, 731 (2006); Howell v. State, 151 S.W.3d 450, 467 (Tenn.2004). Thus nothing in the Apprendi line of cases requires that a jury find the absence of mental retardation beyond a reasonable doubt.

¶ 45 The Supreme Court itself has signaled that a jury need not decide the issue of mental retardation. When the Ninth Circuit suspended federal habeas proceedings in Schriro v. Smith and ordered a state jury trial on the issue of mental retardation, the Supreme Court summarily reversed the decision, implicitly rejecting the conclusion that Atkins requires a jury trial. — U.S.-, -, 126 S.Ct. 7, 9, 163 L.Ed.2d 6 (2005) (per curiam). The defendant in Schriro had argued that he suffered from mental retardation and could not be executed. Id. at 8. Observing that Arizona and many states had adopted procedures for adjudicating the mental retardation question, the Court said, “While those measures might, in their application, be subject to constitutional challenge, Arizona had not even had a chance to apply its chosen procedures when the Ninth Circuit preemptively imposed its jury trial condition.” Id. at 9. Although we hesitate to read too much into the summary reversal, we draw from it a suggestion that a jury trial is not required.

¶ 46 Grell also compares the mental retardation finding to Enmund/Tison findings, arguing that both are findings of fact that should be made by the jury beyond a reasonable doubt. See Tison v. Arizona, 481 U.S. 137, 107 S.Ct. 1676, 95 L.Ed.2d 127 (1987); Enmund v. Florida, 458 U.S. 782, 102 S.Ct. 3368, 73 L.Ed.2d 1140 (1982). The analysis fails for two reasons. First, the Supreme Court has held that Enmund/Tison findings, that a defendant actually killed or intended to kill, need not be made by a jury. See Cabana v. Bullock, 474 U.S. 376, 385-86, 106 S.Ct. 689, 88 L.Ed.2d 704 (1986), abrogated on other grounds by Pope v. Illinois, 481 U.S. 497, 503 n. 7, 107 S.Ct. 1918, 95 L.Ed.2d 439 (1987). The Court’s reasoning — that Enmund/Tison findings serve to disqualify an otherwise seemingly death-eligible defendant from death — suggests that that part of the opinion will survive Apprendi, because the findings mitigate rather than aggravate a potential sentence. Id.; see also Ring III, 204 Ariz. at 564, ¶ 100, 65 P.3d at 945 (concluding that Cabana survives Apprendi because it involves an Eighth Amendment proportionality analysis, traditionally done by a trial judge). Similarly, mental retardation serves to exclude a defendant from eligibility *527for the death penalty; its absence does not render an otherwise ineligible defendant eligible for the death penalty.

¶ 47 Second, Enmund/Tison findings lend themselves more logically to proof beyond a reasonable doubt than does proof of mental retardation. Enmund/Tison findings are based on evidence of participation in the crime and intent. Mental retardation, on the other hand, requires evaluation of the defendant’s past and present mental functioning, using documentation and evidence largely within the control of the defendant. Placing the burden on the prosecution to prove lack of retardation beyond a reasonable doubt would require it to prove a negative against a party with a motive to misrepresent his mental health and his past. The burden on the prosecution would be almost impossibly high.

¶48 Grell argues not only that the jury should hear the mental retardation evidence in mitigation, but also that it should decide whether mental retardation should serve as a bar to execution following an initial determination by the trial judge on that issue. Because Atkins left the procedure for determining mental retardation to the states, such a procedure would not be prohibited; but neither is it required. Indeed, the statute already requires that both the judge and jury evaluate mental retardation before a sentence of death may be imposed. The judge hears mental retardation evidence as a legal bar to execution and the jury hears it for mitigation purposes.

¶49 Grell acknowledges that having the jury serve as the only arbiter of mental retardation is not wise. The difficulties a mentally retarded person may have in testifying, communicating, and expressing remorse may negatively influence the jury. That factor formed an explicit basis of the Supreme Court’s prohibition on execution of the mentally retarded. See Atkins, 536 U.S. at 320-21, 122 S.Ct. 2242. But because the statute requires an initial judicial determination, Grell’s concern is ameliorated. The trial court did not err in determining that a jury need not determine mental retardation as a bar to execution.

B. Preclusion of Testimony from Defense Expert Dr. Keyes

¶ 50 Defense counsel protests the exclusion of his third mental health expert as an unnecessarily harsh penalty for Grell’s refusal to cooperate with the State’s third mental health expert. “Whether to preclude ... a witness’s testimony lies within the discretion of the trial court.” Moody, 208 Ariz. at 457, ¶ 135, 94 P.3d at 1152. We will not reverse a sanction unless the trial court has abused its discretion. Id.

¶51 The State moved to preclude Dr. Keyes from testifying about Grell’s adaptive abilities after Grell refused to cooperate with the State’s new mental health expert. Relying on State v. Druke, 143 Ariz. 314, 693 P.2d 969 (App.1984), and State v. Schackart, 175 Ariz. 494, 858 P.2d 639 (1993), the trial court granted the State’s unopposed motion. Concluding that it would be unfair to the State to allow the new defense expert when the State’s new expert could not examine Grell, the court also denied the defense Motion to Reconsider, filed after Dr. Keyes filed a report concluding that Grell has mental retardation.

¶ 52 Defense counsel argues that Drake, Schackart, and cases relating to insanity experts should not control Grell’s case because mental retardation differs from insanity or impulsive behavior. Mental retardation, by definition, must exist before age eighteen. Grell argues that his current mental condition is therefore of only limited relevance. The State’s expert, Dr. Scialli, stated as much in his testimony. Grell also emphasizes the difference between requiring the State to face a defense expert with no expert of its own, and having it face three defense experts with two experts of its own. The latter situation, he argues, does not prejudice the State’s case.

¶ 53 While it may be true that an expert could have evaluated Grell’s adaptive skills without interviewing him, the controlling statute defines mental retardation as including current impairment in adaptive ability. See A.R.S. § 13-703.02(K). Assessments based on recent interviews of the defendant are thus persuasive. Accordingly, the trial judge has discretion to preclude mental *528health experts as a sanction for the defendant’s refusal to cooperate with interviews and testing. Phillips v. Araneta, 208 Ariz. 280, 285, ¶ 15, 93 P.3d 480, 485 (2004). Although such a sanction weighs especially heavily in a capital case, faced with the State’s reduced ability to rebut Dr. Keyes’ assessment of Grell’s current functioning, the judge did not abuse her discretion by precluding Dr. Keyes’ testimony.

C. Denial of Motion to Strike Testimony of Dr. Scialli

¶ 54 The defense argues that Dr. Scialli is not a qualified expert under A.R.S. § 13-703.02, the pretrial screening statute the trial court was attempting to follow, and his testimony, should therefore have been precluded.

¶ 55 Whether a statute applies in a particular situation is a question of law, which we review de novo. Schoneberger v. Oelze, 208 Ariz. 591, 594, ¶ 12, 96 P.3d 1078, 1081 (App.2004). We review the decision to admit or exclude evidence for abuse of discretion. State v. Aguilar, 209 Ariz. 40, 49, ¶ 29, 97 P.3d 865,874 (2004).

¶ 56 Section 13-703.02(K)(3) defines a “psychological expert” as “a psychologist licensed pursuant to title 32, chapter 19.1 with at least two years’ experience in the testing, evaluation and diagnosis of mental retardation.”11 Dr. Scialli is a psychiatrist, not a psychologist. The record shows that he has had training in mental retardation for a child psychiatry fellowship, has been a consultant with several government agencies, has “evaluated and consulted on” children with mental retardation for Child Protective Services, and has been the acting medical director for the Division of Developmental Disabilities, the agency responsible for the care of mentally retarded children and adults.

¶57 This court in Grell I acknowledged that A.R.S. § 13-703.02 should be applied to the hearing on remand only “insofar as is practical.” The trial court reasonably concluded that it was not practicable to apply the statute on this issue. The State hired Dr. Scialli before it could possibly have known the yet-unpassed statute’s requirements for qualifications of experts. In addition, Dr. Scialli appears to be qualified to diagnose and discuss retardation issues. Indeed, the defense relies on his testimony to support its own points about the diagnosis of retardation. And precluding Dr. Scialli’s testimony would have left the State without an expert on mental retardation. His qualifications in this instance bear on the weight of his testimony, not its admissibility. The court did not abuse its discretion by allowing Dr. Scialli to testify.

D. Error in Finding that Grell Did Not Prove Mental Retardation

¶ 58 The defense asserts that the trial court erred in concluding that Grell does not have mental retardation and requests that we review that ruling. The decision was based largely on expert testimony; the trial court determined that the State’s expert was more credible. “The trial judge has broad discretion in determining the weight and credibility given to mental health evidence.” State v. Doerr, 193 Ariz. 56, 69, ¶ 64, 969 P.2d 1168, 1181 (1998). ‘We defer to the trial court’s factual findings that are supported by the record and not clearly erroneous.” State v. Rosengren, 199 Ariz. 112, 116, ¶ 9, 14 P.3d 303, 307 (App.2000).

¶ 59 Because the parties stipulated that Grell had a low IQ before age eighteen, the only issue in the hearing on remand was his adaptive functioning. Under Arizona law, the adaptive functioning component of a mental retardation diagnosis requires “significant impairment” in “the effectiveness or degree to which the defendant meets the standards of personal independence and social responsibility expected of the defendant’s *529age and cultural group.” A.R.S. § 13-703.02(K)(1), (K)(2).

¶ 60 Defense counsel relied primarily on school and juvenile detention records to highlight examples of poor academic and social behavior. He argued that school and detention workers did not diagnose students based on the DSM-IV,12 and thus the fact that no one had diagnosed Grell as having mental retardation did not establish the absence of that condition. He urged the court to find deficits in the areas listed in the DSM-IV.

¶ 61 The State countered with three main themes: no doctor before defense expert Dr. Globus had ever diagnosed Grell as having mental retardation; behaving badly does not necessarily indicate adaptive deficits; and Grell can behave himself when he wants to do so. The State relied on the Vineland Scale as the only test administered to Grell as a youth that would reveal retardation. The score on that scale was low-average, assessing his intelligence as being only a year younger than his chronological age at the time. After moving to Arizona, five psychiatric reports all showed Grell to have a personality or conduct disorder, but none indicated mental retardation. Several school documents literally say that Grell demonstrated “good adaptive skills.” The State also highlighted a ruse Grell concocted about his life following an arrest for robbery in 1996. Although he was twenty at the time, Grell claimed to be a juvenile named Michael Prentice and described a background different from his own in a number of respects. Grell maintained the ruse for more than six months through repeated contacts with the justice system.

¶ 62 The defense claims to have clearly shown that Grell has deficits in two of the eleven areas listed in the DSM-IV and therefore has mental retardation. The DSM-IV definition of mental retardation, however, while similar in overall meaning, is not the same as the statutory definition. See A.R.S. § 13-703.02(K). The statute requires an overall assessment of the defendant’s ability to meet society’s expectations of him. It does not require a finding of mental retardation based solely on proof of specific deficits or deficits in only two areas.

¶ 63 Reasonable minds may differ as to how to interpret the evidence presented. The evidence does, however, support a finding that Grell was able to function at a level higher than that of “significant impairment.” The trial judge’s conclusion was reasonably supported by evidence. The trial court did not clearly err in finding that Grell failed to prove mental retardation by clear and convincing evidence.

E. Entitlement to Jury Sentencing

¶ 64 Grell argues that he is entitled to jury sentencing by the terms of his trial-by-submission agreement. He asserts that he “agreed to a trial by submission in exchange for preserving his claim that the United States Constitution entitled him to a jury determination of aggravation or mitigation at the sentencing phase.” The cover statement of the stipulation states: “This stipulation shall in no way constitute a waiver of any rights the defendant may have to have a jury empanelled to determine the existence or absence of any aggravating and or mitigating circumstances.”

¶ 65 The State acknowledges that Grell attempted to preserve his right to a jury trial for sentencing. It argues, however, that Grell preserved only any “right [he] may have” to a jury sentencing, not an absolute right to such a proceeding. Under Ring, the State thus maintains, Grell has a right to a jury sentencing only if the judicial sentencing was not harmless error.

¶ 66 While that may be one way to interpret the jury sentencing provision, Grell clearly believed that the stipulation would entitle him to a jury trial on aggravating facts if the Ring challenge was successful. When the parties signed the agreement in September 2000, Apprendi had just been decided. Its reasoning suggested that Arizona’s judge-sentencing system was unconstitutional. Grell’s stipulation was thus not a *530meaningless reservation of a pipe-dream right. Moreover, because Grell admitted the act of killing his daughter, the sentencing hearing held increased significance as his only chance to avoid a sentence of death. He waived his right to a jury trial on the guilt-phase issues at least in part based on assurances that he would retain his right to be sentenced by a jury.

¶ 67 We find that the agreement entitles Grell to a jury sentencing. We therefore vacate the sentence of death and remand for a sentencing proceeding in accordance with A.R.S. §§ 13-703 and 13-703.01 (Supp.2002).

F. Other Issues

¶ 68 Grell raised several other issues, all of which are rendered moot by the remand for resentencing. We therefore decline to address them.

III. Conclusion

¶ 69 We affirm the trial court’s determination that Grell does not have mental retardation. Because we conclude that the State is bound by its agreement to afford a jury trial on sentencing, we vacate Grell’s death sentence and remand the case for resentencing in accordance with A.R.S. §§ 13-703 and 13-703.01.

CONCURRING: RUTH V. McGREGOR, Chief Justice, MICHAEL D. RYAN, Justice and SHELDON H. WEISBERG, Judge.*

. A more complete account of the crime appears in Grell I, 205 Ariz. at 58-59, ¶¶ 3-15, 66 P.3d at 1235-36.

. The "heinous, cruel, or depraved” aggravator is written in the disjunctive and the state need prove only one of the three conditions to trigger application of the aggravating circumstance. State v. Gretzler, 135 Ariz. 42, 51, 659 P.2d 1, 10 (1983). Heinousness and depravity are, however, frequently analyzed together as both involve the defendant's mental state. Id.

. The trial court's Special Verdict does not explain the import of this factor, but we infer from the subsequent citation to Gretzler that the judge meant that the defendant relished his crime. See Gretzler, 135 Ariz. at 52, 659 P.2d at 11.

. The court did not state its criteria for determining mental retardation, but the discussion of IQ scores and adaptive skills covers two of the three factors cited by the Supreme Court in Atkins and this court in Grell I as useful in determining the existence of mental retardation: low IQ, poor adaptive skills, and onset before age eighteen. The criteria are based on the Diagnostic Criteria for Mental Retardation, Diagnostic & Statistical *520Manual of Mental Disorders (4th ed. 1994) ("DSM-IV”) and are substantially consistent with the statutory definition in A.R.S. § 13-703.02(K)(2) (2002), which was enacted after Grell's sentencing.

. Section 13-703.02, enacted before Atkins issued but after Grell’s sentencing, defines the pretrial process for evaluating mental retardation in capital cases. First, the trial judge appoints a pre-screening expert to administer an IQ test to the defendant. A.R.S. § 13-703.02(B). If the resulting score is 75 or below, the judge picks one expert nominated by each party, or one jointly nominated expert, to test the defendant again. A.R.S. § 13-703.02(D). If any test result is 70 or below, the court conducts a hearing at which the defendant must prove by clear and convincing evidence that he has "significantly subaverage general intellectual functioning [an IQ of 70 or lower], existing concurrently with significant impairment in adaptive behavior, where the onset of the foregoing conditions occurred before the defendant reached the age of eighteen.” A.R.S. § 13-703.02(G), (K). If the court finds that the defendant's IQ is 65 or below, a rebuttable presumption of mental retardation arises. A.R.S. § 13-703.02(G). If the court does not find mental retardation, the defense may still argue the issue to the jury as a mitigating factor. A.R.S. § 13-703.02(H).

. The statute currently provides for a bifurcated process, see supra note 5, but the jury hears the mental retardation evidence only as a mitigating factor. See A.R.S. § 13-703.02(H).

. The following statutes, passed in 2003 after Atkins, impose a preponderance standard: Cal.Penal Code § 1369 (West, Westlaw through 2006 Sess.); Idaho Code Ann. § 19-2515A (Westlaw through 2005 Sess.); 725 111. Comp. Stat. Ann. 5/114-15 (West, Westlaw through 2005 Sess.); Nev.Rev.Stat. Ann. § 174.098 (West, Westlaw through 2005 Sess.); Utah Code Ann. § 77-15a-104 (West, Westlaw through 2005 2d Sess.); Va.Code Ann. § 19.2-264.3:1.1 (West, Westlaw through 2005 Sess.). The following cases, from jurisdictions in which no statute sets a burden, set preponderance as the appropriate standard: State v. Williams, 831 So.2d 835, 860 (La.2002); Russell v. State, 849 So.2d 95, 148 (Miss.2003); State v. Lott, 97 Ohio St.3d 303, 779 N.E.2d 1011, 1015 (2002); Commonwealth v. Mitchell, 576 Pa. 258, 839 A.2d 202, 211 n. 8 (2003); Franklin v. Maynard, 356 S.C. 276, 588 S.E.2d 604, 606 (2003); Ex parte Briseno, 135 S.W.3d 1, 12 (Tex.Crim.App.2004).

Delaware, which passed its statute within a month of Atkins, is the lone exception. Del.Code Ann. Tit. 11, § 4209 (West, Westlaw through 2005 Sess.) (imposing a clear and convincing burden). Of the eighteen states that had statutes in place before Atkins, thirteen states use the preponderance standard. See Atkins, 536 U.S. at 314-15 & nn. 12-15, 122 S.Ct. 2242.

. By selecting an IQ of 65 as the number that gives rise to the presumption of retardation— which presumption assumes the existence of “significantly subaverage general intellectual functioning,” concurrent “significant impairment in adaptive behavior,” and onset before age eighteen, A.R.S. § 13-703.02(K)(2) — the legislature has given added protection to those defendants whom the DSM-IV would define as having "mild” mental retardation. DSM-IV 42-43.

. A Georgia statute requires the defendant to establish mental retardation by proof beyond a reasonable doubt, a burden that the Georgia Supreme Court has twice upheld. See Head v. Hill, 277 Ga. 255, 587 S.E.2d 613, 621 (2003) (post-Atkins case analyzing Georgia Code Annotated § 17-7-131 (West, Westlaw through 2005 Special Sess.)); Mosher v. State, 268 Ga. 555, 491 S.E.2d 348 (1997) (pre-Atkins case). Because the procedure under the Georgia statute differs substantially from that under the Arizona statute, however, we do not rely on the analysis in Head and Mosher. In those cases, the Georgia Supreme Court found the twin requirements that the defendant need only demonstrate incompetence to stand trial by a preponderance of the evidence and may prove mental retardation to a jury by proof beyond a reasonable doubt sufficient to safeguard mentally retarded persons against the special risks of trial to which they are subject. Head, 587 S.E.2d at 622. Arizona’s safeguards are, if anything, more protective of the rights of the defendant than are Georgia’s.

. Grell’s risk at this post-trial proceeding was of course different, but the outcome is functionally the same because he retains the right to present the evidence of mental retardation to the jury in mitigation. See infra ¶¶ 64-67.

. Section 32-2071 requires a "doctoral degree” from an accredited program in any of several areas of psychology. The program must include hundreds of hours of supervised training. A.R.S. § 32-2071(D). Among the required subjects of study are "interviewing and the administration^ scoring and interpretation of psychological test batteries for the diagnosis of cognitive abilities and personality functioning.” A.R.S. § 32-2071(A)(4)(g). Psychiatrists have medical training and receive an M.D. rather than a Ph.D.

. The DSM-IV instructs that poor adaptive skills exist when there are deficits in at least two of the following areas: communication, self-care, home living, social/interpersonal skills, use of community resources, self-direction, functional academic skills, work, leisure, health, and safety.

BALES, Justice,
concurring in part and dissenting in part.

¶70 Based on the Supreme Court’s decisions in Atkins and Cooper, I do not believe that the federal constitution allows states to execute defendants who are more likely than not mentally retarded but who cannot prove their retardation by the higher standard of clear and convincing evidence. Accordingly, I respectfully dissent from my colleagues’ decision to uphold the clear and convincing standard contained in A.R.S. § 13-703.02(G).

¶ 71 “[Djeath is not a suitable punishment for a mentally retarded criminal.” Atkins, 536 U.S. at 321, 122 S.Ct. 2242. Although Atkins allows states to develop appropriate ways to enforce this constitutional restriction, id. at 317, 122 S.Ct. 2242, the procedures adopted must themselves pass constitutional muster. Cooper outlines the proper framework for determining if a statutorily-assigned standard of proof on the issue of mental retardation comports with due process.

¶72 The majority recognizes that, while the right not to be executed if mentally retarded is of “recent vintage,” both this right (Atkins) and the right not to stand trial if incompetent (Cooper) are “constitutional right[s] based on modern consensus and historical views” of the issues. Op. ¶ 32; accord Pruitt v. State, 834 N.E.2d 90, 100-03 (Ind. 2005) (noting that the Supreme Court has identified the right of mentally retarded defendants not to be executed as grounded in a fundamental principle of justice). I agree with the majority that, just as states may place on defendants the burden of proving competency, states may place on defendants the burden of proving mental retardation. Op. ¶ 29.

¶ 73 My disagreement with the majority concerns the standard, rather than the burden, of proof. In arguing for a clear and convincing standard, the majority notes that there are “significant differences” between the right of the incompetent not to be tried and the right of the retarded not to be executed. Id. ¶38. Noting differences in these constitutional rights does not itself justify requiring defendants to prove retardation by the higher standard of proof; nor does it substitute for actually applying the Cooper analysis. Moreover, the difference between a defendant who might be executed if a court incorrectly rejects a claim of mental retardation and an incompetent defendant who might erroneously be subjected to a trial does not support imposing a higher standard on the former as compared to the latter.

¶ 74 Nor can the majority justify a higher standard of proof by comparing the rights of *531the retarded and the mentally insane. Id. ¶ 40. The standard of proof arguably should be higher for eve-of-execution claims of insanity by defendants who were competent to be tried and sentenced to death as compared to defendants who claim to be mentally retarded, a permanent condition which must be established by evidence of onset before age eighteen. Cf. Ford v. Wainwright, 477 U.S. 399, 426, 106 S.Ct. 2595, 91 L.Ed.2d 335 (1986) (Powell, J., concurring) (noting state may presume defendant remains sane and require defendant to make substantial threshold showing to obtain hearing on post-sentencing claim of insanity). Moreover, since Cooper, neither the Supreme Court nor this court has addressed whether a state can, consistent with the constitution, execute a person who is more likely than not insane. Thus, the fact that Arizona statutes require defendants to establish mental incompetence (i.e., insanity) by clear and convincing evidence as a bar to execution, see A.R.S. § 13-4022(F), does not resolve whether the higher standard can constitutionally apply to that issue or to the issue of mental retardation.13

¶ 75 Our legislature enacted A.R.S. § 13-703.02 before Atkins held that executing a mentally retarded defendant violates the Eighth Amendment’s prohibition against cruel and unusual punishment, 536 U.S. at 316, 321, 122 S.Ct. 2242. Thus, A.R.S. § 13-703.02 does not reflect a legislative effort to adopt a statute in light of the constitutional prohibition. Since Atkins, as the majority acknowledges, all but one of those states that have set the standard of proof for proving mental retardation have adopted a preponderance standard. Op. ¶ 32.

¶ 76 The majority, however, discounts the significance of the standard of proof by arguing that, because Arizona’s statutes provide for a pretrial determination of mental retardation, “the defendant’s risk ... is not death, but a capital trial.” Id. ¶ 35. The majority further states that the ability of defendants to present mental retardation evidence as mitigation during the sentencing hearing reduces “the ultimate risk they face from an adverse determination” under the clear and convincing standard for the pretrial hearing. Id.

¶ 77 The flaw in this analysis is that the pretrial hearing under A.R.S. § 13-703.02 is the defendant’s only opportunity to secure his constitutional rights under Atkins. See id. ¶ 48 (“The judge hears mental retardation evidence as a legal bar to execution and the jury hears it for mitigation purposes.”); cf. id. ¶ 31 (recognizing that the competency hearing provides “those defendants’ only opportunity to contest competency”). Under our statutes, the jury does not decide the Atkins issue when it makes its sentencing determination. See id. ¶48. Instead, each juror makes his or her own decision whether the defendant has proven any mitigating facts and how such facts should be valued. A.R.S. § 13-703(C); State ex rel. Thomas v. Granville, 211 Ariz. 468, 471 ¶ 12 n. 3, 123 P.3d 662, 665 n. 3 (2005).14

*532¶ 78 Mitigation does not go to the constitutional issue in Atkins. Even before Atkins, a defendant could argue mental retardation as relevant mitigation evidence. Penny v. Lynaugh, 492 U.S. 302, 319-20, 109 S.Ct. 2934, 106 L.Ed.2d 256 (1989) (holding that, although the constitution did not prohibit execution of mentally retarded defendants, the defendant must be allowed to present mental retardation as mitigation evidence); see also A.R.S. § 13-703(G). Atkins, however, made clear that the ability to argue mitigation is not sufficient to avoid the constitutional issue as “[m]entally retarded defendants in the aggregate face a special risk of wrongful execution.” 536 U.S. at 321, 122 S.Ct. 2242 (abrogating Penny, 492 U.S. at 323-25, 109 S.Ct. 2934).15

¶ 79 Although one or more jurors may find that the defendant has proven mental retardation by a preponderance of the evidence, the jurors remain free to decide that such evidence is not sufficiently substantial to call for leniency and to impose a death sentence. See A.R.S. § 13-703(0); Granville, 211 Ariz. at 471 ¶ 12 n. 3, 123 P.3d at 665 n. 3. Indeed, as the Supreme Court noted in Atkins, reliance on mental retardation as a mitigating factor can be a “two-edged sword” because the jury may consider the same evidence as supporting the imposition of a death sentence. 536 U.S. at 321, 122 S.Ct. 2242 (noting that mental retardation may enhance likelihood of finding of aggravating factor of future dangerousness). We cannot uphold a clear and convincing standard by relying on the very process the Atkins court determined was insufficient to protect the constitutional rights of the mentally retarded.

¶ 80 In addition, the majority reasons that a clear and convincing standard is constitutional because Atkins recognized that, while there is national consensus against executing the mentally retarded, “people may disagree over which individuals in fact have mental retardation.” Op. ¶ 37. States must protect those defendants who fall within the national consensus on mental retardation, but “are otherwise free to craft their laws for determining which defendants meet the consensus standard.” Id. But the fact that the Court has afforded states some flexibility in substantively defining mental retardation in no way answers whether states may constitutionally execute those defendants who prove they are more likely than not retarded under any applicable definition.

¶ 81 The majority attempts to argue that A.R.S. § 13-703.02 protects those defendants who fall within the national consensus by providing them with “a comparatively lower bar” while requiring defendants with higher IQ scores to “go to greater lengths to prove their mental retardation.” Id. This argument mistakenly assumes the “national consensus” embraces only defendants whose IQs are 65 or below and it fails to recognize how the statute actually works even as to those defendants. Although A.R.S. § 13-703.02 creates a rebuttable presumption of mental retardation for defendants whose IQ scores are 65 or below, this presumption shifts only the burden of production, not the burden of persuasion, to the State. State v. Arellano, — Ariz. -, - ¶¶ 11-12, -, P.3d -,-, 2006 WL 1412884 (2006). Once the State has come forth with any evidence to rebut the presumption, the defendant still must prove mental retardation by clear and convincing evidence, regardless of IQ scores.

¶ 82 Additionally, the majority dismisses the “special risk of wrongful execution” faced by mentally retarded defendants by stating “it does not suggest the need for any particular procedure to ascertain mental retardation.” Op. ¶36. The majority asserts that the clear and convincing standard will assure that “defendants about whom there is a consensus against execution will be screened out at the pretrial stage”; other defendants do not “face such a severe risk at sentencing that they may not constitutionally be put through the capital trial process.” Id.

¶ 83 The right of the mentally retarded not to be executed, however, is not limited to *533those defendants who are severely retarded or who otherwise can establish their condition by especially compelling evidence.16 Under Atkins, the Eighth Amendment prohibits the execution of all mentally retarded defendants. See id. ¶ 37 (“[T]he Court in Atkins clearly announced that states may not execute the mentally retarded____”). Defendants who can prove their mental retardation by only a preponderance will not be “screened out”; as a result, they still face the same special risk that, according to Atkins, cannot be remedied during mitigation. 536 U.S. at 320-21, 122 S.Ct. 2242.

¶ 84 Thus, the real issue here, which the majority does not directly confront, is whether the State can constitutionally execute those defendants who prove they are more likely than not mentally retarded but cannot meet the clear and convincing standard under A.R.S. § 13-703.02(G).

¶ 85 The Supreme Court in Cooper applied due process principles to assess a state’s imposing a clear and convincing standard of proof on a criminal defendant. Although Cooper dealt with the constitutional right not to stand trial if incompetent, its framework applies in evaluating the standard of proof on mental retardation. See Pruitt, 834 N.E.2d at 100-03 (applying Cooper to mental retardation issue); State v. Williams, 831 So.2d 835, 859-60 (La.2002) (same); Howell v. State, 151 S.W.3d 450, 463-65 (Tenn.2004) (same); see also Bowling v. Commonwealth, 163 S.W.3d 361, 382 (Ky.2005) (citing Cooper and applying preponderance of the evidence standard as “[w]e have applied ... to a defendant’s burden to prove ineompeteney to stand trial”).

¶ 86 In Cooper, the Court noted that historic and contemporary standards support a fundamental right not to stand trial if incompetent; in Atkins, the Court recognized a similar right not to be executed if mentally retarded. Op. ¶ 32. The Cooper court also noted that most jurisdictions required a preponderance of the evidence or less to show ineompeteney; similarly, most jurisdictions require only a preponderance of the evidence for a showing of mental retardation. Id. & n. 7.

¶ 87 Given the constitutional right at issue, the Court in Cooper weighed the respective interests of the state and the defendant to assess the fundamental fairness of requiring the defendant to prove ineompeteney by clear and convincing evidence. 517 U.S. at 362-67, 116 S.Ct. 1373. “The function of a standard of proof ... is to instruct the fact-finder concerning the degree of confidence our society thinks he should have in the correctness of factual conclusions____” Id. at 362, 116 S.Ct. 1373 (quotation marks and citation omitted). “The more stringent the burden of proof a party must bear, the more that party bears the risk of an erroneous decision.” Id. (quotation marks and citation omitted).

¶ 88 The Cooper court determined that the “consequences of an erroneous determination of competence are dire” for the defendant because he would not be able to communicate with his attorney or exercise other fundamental rights involved in a fair trial. Id. at 364, 116 S.Ct. 1373. In contrast, the injury to the state from an erroneous conclusion that a defendant is incompetent when he in fact is malingering is “modest.” Id. at 365, 116 S.Ct. 1373. The state may incur expense and delay, but such errors are subject to correction in subsequent proceedings and the state may detain the defendant for a reasonable time to determine if he might later become competent. Id. Recognizing that there were important state interests at stake, the Court concluded that, where incompetence is shown by a preponderance of the evidence, “the defendant’s fundamental right to be tried only while competent outweighs the [sjtate’s interest in the efficient operation of its criminal justice system.” Id. at 367, 116 S.Ct. 1373.

¶ 89 Applying Cooper’s weighing of interests framework here, the use of a clear and convincing evidence standard “would signifi*534cantly increase the risk of an erroneous determination” of no mental retardation for defendants who can prove they are more likely than not mentally retarded. Williams, 831 So.2d at 860 (citing Cooper, 517 U.S. at 362-63, 116 S.Ct. 1373). The imposition of the death penalty is serious and permanent; any mistake cannot be undone once the punishment is carried out. See Evans v. State, 389 Md. 456, 886 A.2d 562, 584 (2005) (“Reflected throughout the Supreme Court jurisprudence underlying the Eighth Amendment is the principle that death is different.”).

¶ 90 The State’s interest, in contrast, is at best modest, likely even less than the interest involved in Cooper. See Howell, 151 S.W.3d at 465 (“[Tjhe risk to the petitioner of an erroneous outcome is dire, as he would face the death penalty, while the risk to the State is comparatively modest.”) (citing Cooper, 517 U.S. at 364-65, 116 S.Ct. 1373). At oral argument, counsel for the State candidly acknowledged that the State does not have any “particular interest” in executing those defendants who can establish their mental retardation by a preponderance but not by clear and convincing evidence. To be sure, the State does have an interest in preventing malingering defendants from obtaining erroneous determinations of their mental retardation. But such determinations do not, in contrast to the competency determinations involved in Cooper, prevent the State from concluding criminal proceedings against the defendant; they instead limit the ultimate punishment the State can exact. Additionally, the risks of malingering are reduced because the statutory definition of mental retardation requires proof not only of a low IQ but also significantly impaired adaptive behavior and the onset of such conditions before the age of eighteen. A.R.S. § 13-703.02(E)(2).

¶ 91 When the relative risks are death and a lesser available punishment, “the defendant’s right not to be executed if mentally retarded outweighs the state’s interest as a matter of federal constitutional law.” Pruitt, 834 N.E.2d at 103; accord Williams, 831 So.2d at 860 (“Clearly, in the Atkins context, the State may bear the consequences of an erroneous determination that the defendant is mentally retarded (life imprisonment at hard labor) far more readily than the defendant of an erroneous determination that he is not mentally retarded.”); Howell, 151 S.W.3d at 465 (“The balance, under these circumstances, weighs in favor of the petitioner and justifies applying a preponderance of evidence standard at the hearing.”).

¶ 92 In light of the interests involved, I would hold that the clear and convincing standard of proof under A.R.S. § 13-703.02(G) is unconstitutional because the State cannot, consistent with due process, execute those defendants who show they are more likely than not mentally retarded. Thus, on remand, the trial court should consider whether Grell can establish mental retardation by a preponderance of the evidence before the court conducts further sentencing proceedings before a jury. I otherwise concur in the majority’s opinion.

. The majority notes that the Georgia Supreme Court has upheld a standard of proof beyond a reasonable doubt for defendants claiming to be mentally retarded. Op. ¶ 34 n. 9. The Georgia statutory scheme, which allows a verdict of "guilty but mentally retarded” in felony cases, substantially differs from Arizona’s capital sentencing scheme, as the majority acknowledges. Id. Moreover, the Georgia decisions are not persuasive on the issue presented here. In Head v. Hill, 277 Ga. 255, 587 S.E.2d 613, 621 (2003), the court reasoned that if a defendant may be required to prove insanity beyond a reasonable doubt, see Leland v. Oregon, 343 U.S. 790, 72 S.Ct. 1002, 96 L.Ed. 1302 (1952), then requiring proof of mental retardation beyond a reasonable doubt is also constitutional. This reasoning, however, fails to recognize that, under Atkins, the mentally retarded have a constitutional right not to be executed. Whether the State may assign to the defendant a higher standard for proving non-constitutional defenses at trial does not address whether the State can execute defendants who prove they are more likely than not mentally retarded.

. Cf. Johnson v. State, 102 S.W.3d 535, 541 (Mo.2003) ("[Tjhe jury was not .faced with the Atkins pronouncement: 'death is not a suitable punishment for a mentally retarded criminal.’ Rather, the jury instructions treated mental retardation as a mere mitigating circumstance — ■ not the outright bar to punishment dictated by Atkins.")-, Kristen F. Grunewald, Case Notes, Atkins v. Virginia, 122 S.Ct. 2242, 15 Cap. Def. J. 117, 125 (2002) ("In Atkins, mental retardation acts as a bar to death. In mitigation, mental retardation is a reason to show mercy.").

. This court recognized the substantial difference between considering mental retardation as a possible mitigating factor and treating it as an absolute bar to the death penalty when the court remanded this case for reconsideration in light of Atkins after the trial judge had rejected Grell’s claim of mental retardation as a mitigating factor. See State v. Grell, 205 Ariz. 57, 63, ¶¶ 37-40, 66 P.3d 1234, 1240 (2003).

. Indeed, the defendant in Atkins claimed to be "mildly mentally retarded," 536 U.S. at 308, 122 S.Ct. 2242, and our statute includes mildly mentally retarded defendants, A.R.S. § 13-703.02(K)(4). See also Atkins, 536 U.S. at 308 n. 3, 122 S.Ct. 2242 (noting that "mild” mental retardation is typically used to describe people with an IQ level of 50-55 to approximately 70) (citing Diagnostic and Statistical Manual of Mental Disorders 42-43 (4th ed.2000)).