January 26, 202626 CO 5, 24SC2, People v. Mion

The opinion summaries are not part of the Colorado Supreme
Court’s opinion. They have been prepared solely for the reader’s
convenience. As such, they may not be cited or relied upon. If
there is any discrepancy between the language in the summary
and the opinion, the language in the opinion controls.
ADVANCE SHEET HEADNOTE
January 26, 2026
2026 CO 5
No. 24SC2, People v. Mion—Affirmative Defenses—Involuntary Intoxication—
Statutory Interpretation
Involuntary intoxication is an affirmative defense to all crimes provided that
the intoxication is not “self-induced.” § 18-1-804(3), C.R.S. (2025). “Self-induced
intoxication” occurs when a defendant “knowingly introduce[s]” substances that
the defendant “knows or ought to know” cause intoxication. § 18-1-804(5). The
supreme court holds that, when a defendant contends that there are multiple
intoxicants in a product that he consumed, a substance per section 18-1-804(5) is
the entire product, not each “particular intoxicant” within the product.
Interpreting substance as the entire product allows courts to consider a
defendant’s reasonableness under the “ought to know” prong of the statute and
thus effectuates the legislature’s intent.

The Supreme Court of the State of Colorado
2 East 14th Avenue • Denver, Colorado 80203
2026 CO 5
Supreme Court Case No. 24SC2
Certiorari to the Colorado Court of Appeals
Court of Appeals Case No. 21CA1230
Petitioner:
The People of the State of Colorado,
v.
Respondent:
Isaac U. Mion.
Judgment Reversed
en banc
January 26, 2026
Attorneys for Petitioner:
Philip J. Weiser, Attorney General
Jaycey DeHoyos, Assistant Attorney General
Denver, Colorado
Attorneys for Respondent:
Shulman Chase LLC
Joseph Chase
Denver, Colorado

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JUSTICE BOATRIGHT delivered the Opinion of the Court, in which JUSTICE
GABRIEL, JUSTICE SAMOUR, and JUSTICE BERKENKOTTER joined.
CHIEF JUSTICE MÁRQUEZ dissented.
JUSTICE HOOD dissented.

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JUSTICE BOATRIGHT delivered the Opinion of the Court.
¶1 Isaac U. Mion was charged with aggravated robbery, menacing, and
criminal mischief after an episode of erratic and violent behavior. At trial, Mion
testified that his behavior was caused by “something unknown” in a joint he
smoked; he thus sought to raise the affirmative defense of involuntary
intoxication. That defense applies when a defendant, “by reason of
intoxication . . . lacks capacity to conform his conduct to the requirements of the
law,” provided that his intoxication was not “self-induced.” § 18-1-804(3), C.R.S.
(2025). “Self-induced intoxication” means that a defendant’s intoxication was
voluntary—“caused by substances which the defendant knows or ought to know
have the tendency to cause intoxication and which he knowingly introduced . . . into
his body.”1 § 18-1-804(5) (emphases added).
¶2 The trial court declined to instruct the jury on the involuntary intoxication
defense, but a division of the court of appeals reversed. People v. Mion, 2023 COA
110M, 544 P.3d 111. The division concluded that the statute did not adequately
address situations where “multiple intoxicants” are involved and held that the
defense “is legally cognizable when (1) a defendant knowingly ingests what he
believes to be a particular intoxicant; (2) in so doing, he unknowingly ingests a
1 For our purposes here, “self-induced” intoxication and “voluntary” intoxication
mean the same thing.

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different intoxicant; and (3) it is the different intoxicant that deprives him of the
capacity to conform his conduct to the requirements of the law.” Id. at ¶¶ 2, 37,
544 P.3d at 112, 117 (emphases altered). Because this “was the essence of Mion’s
involuntary intoxication claim,” the division concluded that Mion’s involuntary
intoxication defense was legally cognizable, entitling him to the jury instruction.
Id. at ¶ 2, 544 P.3d at 112. We granted certiorari.2
¶3 The certiorari question essentially addresses whether the division
erroneously eliminated consideration of moral culpability or blameworthiness in
its rule. As we see it, the division’s rule does not consider “innocent mistake” or
any level of blameworthiness because it ultimately defines substance as each
“particular intoxicant.” As we explore below, segmenting potential intoxicants
like this renders moot the “ought to know” prong of the voluntary intoxication
analysis under section 18-1-804(5) and curtails a factfinder’s ability to consider all
of the circumstances involved in obtaining and consuming the intoxicating
substance.3
2 We granted certiorari to review the following issue:
1. Whether the court of appeals erred in adopting a rule that does not
require defendants to provide some evidence of innocent mistake
when invoking the affirmative defense of involuntary intoxication.
3 We do not determine whether a defendant must show evidence of “innocent
mistake” to raise the affirmative defense of involuntary intoxication as this is a
standard that stems from a common law version of involuntary intoxication. See,
e.g., City of Minneapolis v. Altimus, 238 N.W.2d 851, 856 (Minn. 1976). The People

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¶4 We now reverse and hold that, when a defendant contends that there are
multiple intoxicants in a product that he consumed, a substance per section
18-1-804(5) is the entire product, not each “particular intoxicant” within the
product. Thus, we conclude that Mion was voluntarily intoxicated and therefore
barred from raising the involuntary intoxication defense because his condition
was caused by knowingly smoking a joint that he knew or ought to have known
had the tendency to intoxicate.
I. Facts and Procedural History
¶5 A security guard found Mion sleeping on the grounds of the Denver City
and County Building. When the guard asked Mion to leave, Mion acted in an
agitated and erratic manner. He grabbed the guard’s phone from his hand, and
when a second security guard approached to call 911, Mion knocked the phone
out of her hand, cracking the screen. After running away, Mion began yelling at a
civilian and struck the civilian’s truck with a club-like object after the civilian
entered his truck. Officers eventually arrested Mion after he tried to submerge
himself in a creek. During the arrest, Mion yelled at the officers to shoot him and
themselves point out that “[c]ourts are without the authority to extend defenses
that are created and limited by statute.” Determining whether defendants must
show “innocent mistake” to raise the involuntary intoxication defense would do
just that.

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said that he wanted to die. Following these events, the People charged Mion with
aggravated robbery, menacing, and criminal mischief.
¶6 At trial, Mion testified that, earlier that night, he stopped in a doorway in
downtown Denver to drink beer and work on his bike with a “street guy” he knew.
Mion admitted that he did not know this man’s name, but when the man offered
Mion a joint, Mion accepted it and took “two hits.” About twenty minutes later,
Mion began feeling paranoid and later blacked out, claiming that he remembered
nothing else from that evening.
¶7 Relying on this testimony, Mion requested a jury instruction on the
affirmative defense of involuntary intoxication, alleging that there was
“something unknown” in the joint he smoked, like a stimulant, that caused his
erratic behavior. The trial court found this claim to be “pure speculation” and
denied Mion’s request. A jury found Mion guilty of robbery, menacing, and
criminal mischief.
¶8 A division of the court of appeals reversed. Mion, ¶ 56, 544 P.3d at 120. The
division concluded that the involuntary intoxication statute does not “squarely
address . . . the ingestion of multiple intoxicants.” Id. at ¶ 37, 544 P.3d at 117. It
then held that the affirmative defense of involuntary intoxication “is legally
cognizable when (1) a defendant knowingly ingests what he believes to be a
particular intoxicant; (2) in so doing, he unknowingly ingests a different intoxicant;

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and (3) it is the different intoxicant that deprives him of the capacity to conform
his conduct to the requirements of the law.” Id. at ¶ 2, 544 P.3d at 112 (emphases
altered). The division held that Mion’s defense under this three-part test was
legally cognizable given that this “was the essence of Mion’s involuntary
intoxication claim.” Id. We granted certiorari.
II. Analysis
¶9 We begin by addressing our standard of review and applicable principles of
statutory construction. Next, we demonstrate how the definition of “[s]elf-
induced intoxication,” which, when met, precludes defendants from raising the
involuntary intoxication defense under section 18-1-804, consists of two distinct
prongs: (1) whether a defendant “knowingly introduce[s]” a substance; and
(2) whether the defendant “knows or ought to know” of the substance’s tendency
to intoxicate. § 18-1-804(5). We then conclude that the term “substances” in
section 18-1-804(5) is ambiguous, allowing us to consider the consequences of
various constructions to effectuate the legislature’s intent. From there, we explain
how in cases such as this one, where a defendant contends that there are multiple
intoxicants in a product that caused their intoxication, construing the substance as
the entire product, rather than as any “particular intoxicant,” reflects legislative
intent. Finally, we re-examine whether Mion was entitled to raise an involuntary

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intoxication defense under this construction of the statute and determine that he
was not.
A. Standard of Review and Principles of Statutory
Construction
¶10 Whether the division correctly interpreted section 18-1-804 is a question of
law that we review de novo. People v. Garcia, 113 P.3d 775, 780 (Colo. 2005).
¶11 In construing a statute to give effect to the legislative intent, we start with
the language of the statute, giving words and phrases their plain and ordinary
meanings. See, e.g., People v. Cali, 2020 CO 20, ¶ 15, 459 P.3d 516, 519. However,
“[a] statute is ambiguous when it is reasonably susceptible of multiple
interpretations.” McCoy v. People, 2019 CO 44, ¶ 38, 442 P.3d 379, 389. If a statute
is ambiguous, a court may consider other aids of construction, such as the
legislative history, the purpose of the statute, and the consequences of a particular
construction to give effect to legislative intent. § 2-4-203(1), C.R.S. (2025); McCoy,
¶ 38, 442 P.3d at 389.
B. Colorado’s Involuntary Intoxication Defense
¶12 The legislature has established involuntary intoxication as an affirmative
defense to all crimes: “A person is not criminally responsible for his conduct if, by
reason of intoxication that is not self-induced at the time he acts, he lacks capacity
to conform his conduct to the requirements of the law.” § 18-1-804(3) (emphasis
added). A defendant’s intoxication is self-induced, or voluntary, when it is caused

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by substances that the defendant: (1) “knowingly introduced” and that (2) he
“knows or ought to know” cause intoxication:
“Self-induced intoxication” means intoxication caused by substances
which the defendant knows or ought to know have the tendency to cause
intoxication and which he knowingly introduced or allowed to be
introduced into his body, unless they were introduced pursuant to
medical advice or under circumstances that would afford a defense to
a charge of crime.
§ 18-1-804(5) (emphases added).
¶13 Therefore, when analyzing whether a defendant may raise the affirmative
defense of involuntary intoxication under section 18-1-804, a court must determine
whether a defendant has offered some evidence that their intoxication was not self-
induced. The affirmative defense of involuntary intoxication is unavailable if a
defendant’s intoxication was self-induced—if their conduct was caused by one or
more “substances” which they both (1) “knowingly introduced” and (2) knew or
ought to have known would have a tendency to cause intoxication. § 18-1-804(5).
¶14 This definition entails two requisite levels of responsibility or
blameworthiness involved in voluntarily intoxicating oneself.4 A person acts
“[k]nowingly” when they have an awareness of the nature of their conduct and the
4 The parties’ arguments concerning blameworthiness rely on common law
principles of involuntary intoxication. See, e.g., Altimus, 238 N.W.2d at 856.
However, because involuntary intoxication is codified in Colorado, and “[s]elf-
induced intoxication” is specifically defined, we adhere to the levels of responsibility
or blameworthiness envisioned by section 18-1-804(5), through the language of
“knowingly” and “ought to know.”

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circumstances. § 18-1-501(6), C.R.S. (2025); People v. Krovarz, 697 P.2d 378, 381–82
(Colo. 1985); see also People v. Etchells, 646 P.2d 950, 951 (Colo. 1982) (“The statutory
definition of ‘knowingly’ requires that the jury find that the defendant was
‘aware,’ not ‘should have been aware.’” (quoting § 18-1-501(6))).
¶15 Conversely, the phrase “ought to know” engenders a reasonableness
standard: what a reasonable person would have or should have known under the
circumstances. See People v. Turner, 680 P.2d 1290, 1293 (Colo. App. 1983) (holding
that the jury is to weigh the evidence “in light of . . . common knowledge” when
determining if the defendant knew or should have known of the intoxicating
consequences of ingesting excessive doses of a prescription drug); see also
Gatewood v. State, 654 S.W.3d 239, 245 (Tex. Ct. App. 2022) (finding that a jury
could have found the defendant’s intoxication to be “voluntary” because “he
should have known through the exercise of reasonable care that the cigarette . . . could
contain [synthetic marijuana]” (emphases added)).
¶16 Thus, if Mion’s intoxication was caused by a substance which he
“knowingly introduced” and knew or ought to have known had the tendency to
intoxicate, then his intoxication was self-induced, and he was not entitled to a jury
instruction on the involuntary intoxication defense. But, as we explore below, this
analysis necessarily rests on how substance is construed under the facts of this
case.

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C. Substance Is Ambiguous
¶17 The People argue that a substance per section 18-1-804(5) refers to the whole
intoxicating product—here, the whole joint—rather than any of its speculated
components. Thus, the People argue that Mion’s intoxication was self-induced
because he “knowingly introduced” the joint and knew or ought to have known
that it had the tendency to intoxicate. Conversely, Mion characterizes the
substance here as the “something unknown” which he suspects was inside the
joint, rather than the entire joint. He thus claims to have been involuntarily
intoxicated because when he took “two hits” of the joint, he only “knowingly
introduced” marijuana, not the “something unknown” that he maintains caused
his criminal behavior that night. The division agreed with Mion, stating that
“courts must focus on the particular intoxicant that allegedly deprived the
defendant of the capacity to conform his conduct to the requirements of the law.”
Mion, ¶ 37, 544 P.3d at 117.
¶18 The word substance is not defined by the statute. Nor have we previously
considered whether that term applies to an entire product (as the People propose)
or to that product’s individual ingredients (as Mion proposes). Moreover, both
the People’s and Mion’s interpretations of this undefined term are reasonable.
Accordingly, we conclude that this term is ambiguous, allowing us to consider the
consequences of each construction to determine the legislature’s intent.

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D. Defining the Substance as the Entire Product Aligns with
Legislative Intent
¶19 In its holding, the division essentially substituted the phrase “particular
intoxicant” for the word “substances” and concluded that “courts must focus on
the particular intoxicant that allegedly deprived the defendant of the capacity to
conform his conduct to the requirements of the law.” Id. In so doing, the division
interpreted the “substances” to mean each theoretical ingredient contained in the
joint Mion smoked. Although the division recognized that Mion’s behavior in
accepting a joint from a person he barely knew was reckless, it concluded that this
was not relevant as a “matter of law” because “nothing in the involuntary
intoxication statute refers to the concept of recklessness.” Id. at ¶ 41, 544 P.3d at
117 (second emphasis added).
¶20 Under the division’s construction of substance as each “particular
intoxicant” in a product, a defendant could always claim that they did not
“knowingly introduce[]” a substance (by claiming that they consumed an
intoxicating product containing “something unknown”). The involuntary
intoxication analysis would likely never reach the “ought to know” prong, leading
to a practical erasure of this language. As a result, the division’s rule focuses only
on the defendant’s actual awareness and eliminates consideration of their
reasonableness. We deem this to be contrary to the legislature’s intent.

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¶21 Consider the following hypothetical. Someone eats a pot brownie with a
label that clearly indicates that it contains tetrahydrocannabinol (“THC”). This
causes their intoxication and subsequent criminal conduct. If we determine that
the substance is the THC inside the pot brownie (as opposed to the pot brownie
itself), the person could easily claim that they did not look at the label and thus
were not actually aware that the pot brownie contained THC. The analysis ends
there—they would be entitled to raise the defense as a matter of law because they
demonstrated that they did not “knowingly introduce[]” a substance. It would be
irrelevant whether they ought to have known that the pot brownie would have an
intoxicating effect. But, if we determine that the substance is the pot brownie, then
the defendant plainly “knowingly introduced” the substance. Thus, the issue
would become whether the defendant knew or should have known that the pot
brownie would have an intoxicating effect, meaning the court would consider
their reasonableness. Such a construction allows the factfinder to consider all of
the circumstances involved in obtaining and consuming the substance.
¶22 Contrast this with a case where someone takes and eats a brownie at a
potluck with friends, but it turns out to be a pot brownie that causes their
intoxication. If we define the substance as the pot brownie, this hypothetical
defendant would still have the involuntary intoxication defense available to them.
While the defendant “knowingly introduced” the pot brownie, the fact that they

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consumed a dessert from a known friend at a reputable event indicates that they
likely had no reason to know that it was intoxicating under the “ought to know”
prong. Clearly then, this construction of the substance allows courts to consider a
defendant’s reasonableness under the “ought to know” prong of section
18-1-804(5).
¶23 The recently decided case of People v. Williams, 2025 COA 26, 568 P.3d 1267,
demonstrates the foundational issue with the division’s rule. There, Williams was
arrested and charged after he was found walking through his neighborhood,
shooting at people. Id. at ¶¶ 4–5, 568 P.3d at 1270. Williams testified that, even
though he had been drinking, his behavior was caused by hallucinations due to
the methamphetamine he mistakenly ingested. Id. at ¶¶ 3, 6, 568 P.3d at 1270. On
appeal, Williams argued that he was entitled to present the involuntary
intoxication defense under the division’s holding in Mion: He knowingly ingested
what he believed to be a particular intoxicant—cocaine—and instead unknowingly
ingested a different intoxicant—methamphetamine. Id. at ¶ 13, 568 P.3d at 1271.
Without addressing whether Mion was rightly decided, the court held that
Williams could not raise the defense, reasoning that because he started
hallucinating before he took drugs, there was insufficient evidence to suggest that
his “mental disturbances were caused by involuntary intoxication (from suspected
meth) rather than voluntary intoxication (from alcohol).” Id. at ¶ 19, 568 P.3d at

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1272. We agree with the People that “[i]t is highly unlikely that the legislature
intended the intoxication statute to safeguard such a culpable defendant from
criminal liability.”5
¶24 Accordingly, we hold that, when a defendant contends that there are
multiple intoxicants in a product that he consumed, a substance per section
18-1-804(5) is the entire product, not each “particular intoxicant” within the
product. Our interpretation contemplates a defendant’s reasonableness under the
“ought to know” prong of the statute and effectuates the legislature’s intent.
¶25 With this understanding of the term substance in mind, we now consider
whether Mion was entitled to an involuntary intoxication defense.
E. Mion Was Voluntarily Intoxicated
¶26 To raise the involuntary intoxication defense, Mion needed to present “some
credible evidence” on that issue. § 18-1-407(1), C.R.S. (2025). In other words, he
needed to provide “something more than an unsupported assertion” that his
intoxication was not self-induced. Turner, 680 P.2d at 1293. We must review the
5 There is little legislative history. It consists of legislative commentary when the
General Assembly enacted section 18-1-804’s nearly identical predecessor in
1971, noting that the statute was based on a proposed Michigan law. § 40-1-904
cmt., 3 C.R.S. (1963 & Supp. 1971). In turn, the commentary in that proposed
Michigan law does not give direct insight into the Michigan legislature’s intent
regarding the definition of the term “substances,” but only states that “[t]he
emphasis is on the result the substance produces, not its classification.” Mich.
Revised Crim. Code § 715(6) cmt. (Mich. State Bar, Special Comm. & Comm. on
Crim. Juris., Final Draft Sept. 1967).

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record as a whole to determine whether it contains “any evidence tending to
establish” this defense. Garcia, 113 P.3d at 784 (quoting Idrogo v. People, 818 P.2d
752, 754 (Colo. 1991)). We conclude that Mion does not succeed under this
standard.
¶27 Mion acknowledged that the joint caused his intoxication. And Mion did
not provide “some credible evidence” either that he did not “knowingly
introduce[]” the joint or that he did not “know[] or ought to know” that the joint
would have an intoxicating effect. First, Mion knowingly smoked the joint he was
offered when he took “two hits” from it. Second, Mion knew or should have
known that the joint would have an intoxicating effect. While Mion testified that
he assumed the joint contained only marijuana, this was unreasonable.
Significantly, Mion did not obtain the joint from a licensed establishment; to the
contrary, it was a street drug that he accepted from someone whose name he did
not even know. Moreover, he took it and smoked it without even asking what it
was. Hence, we conclude that Mion ought to have known that the substance he
consumed was intoxicating.
¶28 In making his arguments, Mion likens his claim to someone who knowingly
drinks alcohol, but also unknowingly ingests a different drug that causes more
severe intoxication. He therefore contends that defining the substance as the

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whole product would prohibit victims of a spiked drink from raising the
involuntary intoxication defense. We are not persuaded.
¶29 This hypothetical defendant would have access to the involuntary
intoxication defense under language in section 18-1-804(5) that creates an
exception to the “[s]elf-induced intoxication” definition. Per the statute, even if a
defendant knowingly introduced a substance and ought to have known that the
substance was intoxicating, their intoxication is not self-induced if the substance
was “introduced pursuant to medical advice or under circumstances that would afford
a defense to a charge of crime.” § 18-1-804(5) (emphasis added).
¶30 While the language “under circumstances that would afford a defense to a
charge of crime” may be ambiguous, it serves a purpose. See Harvey v. Cath. Health
Initiatives, 2021 CO 65, ¶ 33, 495 P.3d 935, 942 (“We, however, are not at liberty to
alter the wording of a statute. Nor may we interpret statutory language so as to
render any of that language superfluous.”). Unlike Mion, when a person
purchases an alcoholic drink from a licensed facility that is then secretly spiked,
they have no reason to know that their drink was altered. Those circumstances
would “afford a defense to a charge of crime” because these facts significantly
negate the defendant’s intent to voluntarily intoxicate oneself.
¶31 The language of the “[s]elf-induced intoxication” definition in our present-
day involuntary intoxication statute originally stems from, and is nearly identical

18
to, section 2.08(5)(b) of the 1962 Model Penal Code.6 Model Penal Code and
Commentaries § 2.08 (A.L.I., Official Draft & Revised Comments 1962). A notation
about the history of section 2.08 directs us to Tentative Draft No. 9 for the “original
detailed commentary.” Id. This commentary states: “Of course, intoxication
caused by the fraud of another is not self-induced.” Model Penal Code § 2.08 cmt.
6 (A.L.I., Tentative Draft No. 9 1959).
¶32 In the spiked-drink situation, the circumstances foreseeably consist of fraud
or trickery. A hypothetical bar-goer asks for a drink with specific alcohol, a
“bourbon” or a “rum and coke,” but ends up consuming something different once
the drink is spiked by another. But here, Mion presented no evidence that the
“something unknown” was introduced through trickery or other such
circumstance. He was simply handed an unspecified joint which he decided to
smoke.
¶33 Accordingly, we conclude that Mion did not present sufficient evidence to
entitle him to raise the affirmative defense of involuntary intoxication.
6 Our present-day involuntary intoxication statute was based on a proposed
Michigan law which, in turn, was “based primarily on Model Penal Code [section]
2.08.” Mich. Revised Crim. Code § 715(6) cmt. (Mich. State Bar, Special Comm. &
Comm. on Crim. Juris., Final Draft Sept. 1967); § 40-1-904 cmt., 3 C.R.S. (1963 &
Supp. 1971).

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III. Conclusion
¶34 For the foregoing reasons, we reverse the judgment of the court of appeals
and remand the case for further proceedings consistent with this opinion.
CHIEF JUSTICE MÁRQUEZ dissented.
JUSTICE HOOD dissented.

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CHIEF JUSTICE MÁRQUEZ, dissenting.
¶35 The majority interprets section 18-1-804, C.R.S. (2025), to render the
involuntary intoxication defense unavailable as a matter of law to individuals in
Isaac U. Mion’s situation—that is, a person who knowingly ingests one intoxicant,
but who asserts that in so doing, he unknowingly ingested a second, different
intoxicant that caused him to be unable to conform his conduct to the law.
¶36 In reaching this conclusion, the majority defines “substance” as the entire
consumable “product,” rather than the intoxicant—that is, the specific chemical or
material that causes intoxication. Maj. op. ¶ 24. But this approach defies the plain
language of section 18-1-804 and, as pointed out by the court of appeals, exposes
otherwise innocent people to criminal liability. People v. Mion, 2023 COA 110M,
¶ 37, 544 P.3d 111, 117. For these reasons, and because I also conclude that Mion
presented sufficient evidence to warrant a jury instruction on involuntary
intoxication, I respectfully dissent.
I. For Purposes of the Involuntary Intoxication Defense in
Section 18-1-804, the Term “Substance” Logically Refers
to the Intoxicant that Caused a Person to Be Incapable of
Conforming Their Conduct to the Law
¶37 When interpreting a statute, we begin with its plain language and read the
statute “as a whole” to give “consistent, harmonious, and sensible effect to all of
its parts,” i.e., we “read statutory words and phrases in context.” McCoy v. People,
2019 CO 44, ¶¶ 37–38, 442 P.3d 379, 389.

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¶38 The crux of the involuntary intoxication defense appears in section
18-1-804(3), which provides that “[a] person is not criminally responsible for his
conduct if, by reason of intoxication that is not self-induced at the time he acts, he
lacks capacity to conform his conduct to the requirements of the law.” (Emphasis
added.) Notably, this provision defines involuntary intoxication by what it is not:
“self-induced” intoxication.
¶39 The statute goes on to define “[s]elf-induced intoxication” as intoxication
caused by substances which the defendant (1) “knows or ought to know have the
tendency to cause intoxication” and (2) “knowingly introduced or allowed to be
introduced into his body.” § 18-1-804(5) (emphases added). Logically then,
“intoxication that is not self-induced” under section 18-1-804(3) means intoxication
that does not meet one or both prongs of the definition of “[s]elf-induced
intoxication”; that is, intoxication caused by a substance that the defendant (1) did
not “know[] or ought to know” had the tendency to cause intoxication, or (2) did
not “knowingly introduce[]” into his body.
¶40 I agree with Justice Hood that section 18-1-804 focuses on the intoxicant that
caused the defendant’s intoxication, not the “entire product” the defendant
consumed. See Dis. op. ¶ 55 (Hood, J., dissenting). Subsection (4) of the statute
defines “[i]ntoxication” as a “disturbance of mental or physical capacities resulting
from the introduction of any substance into the body.” § 18-1-804(4) (emphases

3
added). And subsection (5) refers directly to “substances which . . . cause
intoxication.” § 18-1-804(5) (emphasis added). These provisions show that the
term “substance” refers to an intoxicant—a particular chemical material that when
ingested causes a “disturbance of mental or physical capacities.” § 18-1-804(4).
Thus, for purposes of the involuntary intoxication defense in section 18-1-804, the
term “substance” refers to the (unknowingly ingested) intoxicant that caused a
person to be incapable of controlling their conduct.
¶41 The majority instead reads “substance” in section 18-1-804 to mean the
“entire product” the defendant consumes—i.e., the drink, the food, or the
cigarette, rather than the specific intoxicant contained in the consumable product
that causes a defendant to be unable to conform their conduct to the requirements
of the law. See Maj. op. ¶ 24. As explained above, this broad reading of
“substance” is not grounded in the statutory language, nor does it comport with
common sense. To borrow the majority’s pot brownie example, see id. at ¶ 21, it is
not a person’s ingestion of the flour, cocoa, or sugar in a brownie that causes
intoxication; it is the marijuana (and specifically—as the majority
acknowledges—the tetrahydrocannabinol (“THC”)).
¶42 The majority’s approach not only defies the statutory language but also
exposes otherwise innocent people to criminal liability by depriving juries of the
ability to fully assess a defendant’s culpability. An adult who responsibly

4
consumes a single cup of alcoholic punch or a cocktail at a party, unaware that the
punch or cocktail is spiked with an illegal stimulant, may not claim involuntary
intoxication even if the accidentally ingested stimulant is what causes the person
to engage in unlawful behavior. The same is true for the adult who lawfully
consumes legal recreational marijuana (say by eating a brownie or smoking a joint)
unaware that the “product” is laced with an additional, potent hallucinogen that
renders them incapable of controlling their behavior. Under the majority’s view,
such individuals are prohibited from arguing to a jury that they did not knowingly
ingest the additional intoxicant that resulted in their unlawful behavior. Instead,
under the majority’s reasoning, the person’s intoxication must be deemed self-
induced because they knowingly ingested the intoxicating “product”: the drink,
the food, or the cigarette.1
1 The majority argues that defining “substance” to refer to the “particular
intoxicant” would allow a defendant to raise an involutory intoxication defense
simply by claiming that they unknowingly ingested an unknown intoxicant. Maj.
op. ¶ 20. I respectfully disagree; the unknowing ingestion of an intoxicant is the
whole point of the involuntary intoxication defense. The majority also suggests
that bar patrons whose drinks are spiked by way of trickery or fraud could still
raise the defense because the definition of self-induced intoxication under section
18-1-804(5) has an exception for substances introduced “under circumstances that
would afford a defense to a charge of crime.” Maj. op. ¶ 29. But it is unclear how
such a defendant could claim involuntary intoxication if, under the majority’s
broad definition of “substance,” the person was not “tricked” into ingesting the
product—i.e., the drink or food— as opposed to the intoxicant. The majority cannot
have it both ways.

5
¶43 Put differently, under the majority’s approach, a person who reasonably
ingests a legal intoxicant unaware that it contains a second intoxicant that causes
their unlawful behavior is barred from raising the involuntary intoxication
defense. Because I believe such individuals should be allowed to argue to a jury
that they are not culpable for their crimes and that holding otherwise is both
illogical and contrary to the statute’s language, I cannot subscribe to the majority’s
interpretation.
¶44 The majority justifies its holding out of fear that the division’s approach
would allow a flood of frivolous involuntary intoxication defenses. But such fears
are overblown. A defendant (such as Mion) who acknowledges that they
consumed one intoxicant, but asserts that they unknowingly ingested a different
intoxicant, will have to present “some credible evidence” that it was the additional
intoxicant that led to their uncontrollable behavior to warrant a jury instruction on
involuntary intoxication.2 § 18-1-407(1), C.R.S. (2025). This burden is precisely
why the division in People v. Williams, 2025 COA 26, 568 P.3d 1267, concluded that
the defense was unavailable in that case. There, the defendant “attempted to raise
2 In addition to being required to present some credible evidence that it was the
additional intoxicant that led to the unlawful behavior, the defendant’s evidence
must indicate that they did not knowingly ingest the additional intoxicant. The
prosecution can disprove such a defense by establishing that the intoxication was
in fact self-induced (because under the circumstances, the defendant knew or
ought to have known they were ingesting an additional intoxicant).

6
an involuntary intoxication defense, asserting that he had intended to use cocaine
but involuntarily consumed a different drug, which he believed was
meth[amphetamine].” Id. at ¶ 6, 568 P.3d at 1270. The evidence in that case,
however, suggested that the defendant was already experiencing the intoxicating
effects of alcohol before consuming the suspected methamphetamine, indicating
that his unlawful behavior was the result of intoxication from his voluntary
consumption of alcohol, not the allegedly involuntary consumption of a different
drug. Id. at ¶¶ 16–17, 568 P.3d at 1272.
¶45 In sum, because the majority’s interpretation is contrary to the statute’s
language and will prohibit otherwise innocent people from raising the defense, I
cannot subscribe to the majority’s interpretation.
II. Mion Raised Sufficient Evidence to Require the Trial
Court to Submit His Involuntary Intoxication Defense to
the Jury
¶46 Because I would hold that Mion’s proffered involuntary intoxication
defense is legally cognizable, I would also consider the factual question of whether
Mion presented sufficient evidence to warrant an involuntary intoxication
instruction. I conclude that he did.
¶47 A defendant is entitled to a jury instruction on an affirmative defense if they
present “some credible evidence” supporting that defense. § 18-1-407(1). Mion
satisfied that burden here.

7
¶48 Mion testified that he assumed the joint offered to him contained only
marijuana and that he perceived nothing unusual about the joint’s smell or taste.
He explained that he had smoked marijuana on hundreds of occasions and
understood how it would affect him. In accordance with those expectations, he
believed that he would be able to complete the tasks he had planned for the day
after smoking the joint and testified that if he believed smoking the joint would
have interfered with his plans, he would not have smoked it. The effects he
ultimately experienced, however, were unlike any effects he had previously felt
after smoking marijuana.
¶49 Testimony from one of the responding officers also suggests that the effects
Mion experienced were different from those experienced after smoking marijuana.
A police officer testified that he did not think someone smoking a joint would be
able to tell the difference between marijuana and spice, and that spice can have
different effects than marijuana; spice acts as a stimulant. Importantly, the officer
testified that he believed Mion was under the influence of a stimulant, making him
“highly animated,” “[a]gitated,” and less compliant in response to pain. And
Mion’s behavior was confirmed by surveillance footage of his offenses and arrest.
¶50 I agree with the court of appeals division that, taken together and viewed in
the light most favorable to Mion, this evidence was sufficient to warrant a jury
instruction on involuntary intoxication. Mion, ¶¶ 45–50, 544 P.3d at 118–19.

8
¶51 A trial court’s failure to give an affirmative defense instruction despite
“‘some credible evidence’” supporting the defense “impermissibly lower[s]” the
prosecution’s burden of proof, “implicating a defendant’s constitutional rights.”
Pearson v. People, 2022 CO 4, ¶ 16, 502 P.3d 1003, 1007 (quoting § 18-1-407(1)).
Accordingly, the trial court’s error here is subject to constitutional harmless error
review. Id. The People do not argue that any error was harmless, let alone
harmless beyond a reasonable doubt. Moreover, the jury’s assessment of the
evidence and of Mion’s credibility could have led it to reasonably conclude that
the People did not disprove the defense of involuntary intoxication beyond a
reasonable doubt. Mion, ¶ 55, 544 P.3d at 120. Accordingly, the trial court’s failure
to instruct the jury on involuntary intoxication constitutes reversible error and
requires a new trial.
III. Conclusion
¶52 The language of the involuntary intoxication defense in section 18-1-804
focuses on the “substance” that caused a person to lose control of their conduct.
“Substance” therefore logically refers to the (unknowingly ingested) intoxicant, not
the “entire product” consumed. The majority’s interpretation of the statute is
contrary to its plain language and, as the division below pointed out, means that
“anytime a person knowingly ingests an intoxicant—no matter how mild—the
person will be criminally responsible for any resulting behavior, even if what was

9
ingested contained, unbeknownst to the defendant, a different intoxicant—no
matter how potent and mind-altering.” Mion, ¶ 37, 544 P.3d at 117. Because I
cannot agree with the majority’s interpretation of the statute, and because I believe
that under a proper interpretation, Mion produced sufficient evidence to warrant
a jury instruction on involuntary intoxication, I respectfully dissent.

1
JUSTICE HOOD dissenting.
¶53 I also respectfully dissent.
¶54 In doing so, however, I acknowledge that the majority’s opinion sets forth a
plausible reading of the plain language of an ambiguous statute. Moreover, it has
the virtue of reducing the potential for all-too-convenient claims of involuntary
intoxication after a defendant chooses to consume unpredictable street drugs and
puts others in harm’s way. In the modern world, the unknown potency of such
drugs is a foreseeable risk. See, e.g., Dangerous Synthetic Drugs: Hearing Before the
S. Caucus on Int’l Narcotics Control, 113th Cong. 8 (2013) https://
www.drugcaucus.senate.gov/wp-content/uploads/2022/11/ Rannazzisi_
Dangerous-Synthetic-Drugs-Testimony-SDC-25Sept13.pdf [https://perma.cc/
EW66-LQ5B] (statement of Joseph T. Rannazzisi, Deputy Assistant Adm’r, Off. of
Diversion Control, Drug Enf’t Admin., about the increased prevalence of anxiety
attacks, hallucinations, and paranoid behavior caused by synthetic cannabinoids).
Because section 18-1-804, C.R.S. (2025) is ambiguous, we are permitted to consider
the consequences of our interpretation. § 2-4-203(1)(e), C.R.S. (2025). All to say
that from a policy perspective, I get it.
¶55 Even so, the central question here is really dictated by the plain language:
What substance “caused” the conduct that deprived the defendant of the ability to
conform his conduct to the requirements of the law? § 18-1-804(4)–(5); People v.

2
Mion, 2023 COA 110M, ¶ 31, 544 P.3d 111, 116. Sifting through evidence of the
defendant’s knowledge of what he ingested and how it affected his behavior is a
quintessential question of fact. Assuming some credible evidence of innocent
mistake, the defendant should be able to put that question before a jury, which can
be trusted to fairly evaluate credibility.
¶56 For the reasons outlined by Chief Justice Márquez, Dis. op. ¶ 48 (Márquez,
C.J., dissenting), and the division below, Mion, ¶ 45, 544 P.3d at 118, Mion
presented the “small quantum” of evidence necessary to require the trial court to
instruct the jury on the defense of involuntary intoxication. Id. at ¶ 43, 544 P.3d at
118 (quoting Galvan v. People, 2020 CO 82, ¶ 24, 476 P.3d 746, 754).
¶57 The Chief also demonstrates how the majority’s interpretation yields
illogical and unfair results. Dis. op. ¶ 42 (Márquez, C.J., dissenting). The majority
waves off the “spiked-drink” problem by observing that Mion (1) didn’t obtain the
marijuana from a licensed establishment, (2) understood he was ingesting a street
drug obtained from someone whose name he didn’t even know, and (3) smoked
it without asking what it was. Maj. op. ¶ 27. In its view, “Mion ought to have
known that the substance he consumed was intoxicating,” so he can’t seek refuge
in the involuntary intoxication statute. Id.
¶58 But if the question is simply whether a defendant ought to have known that
any substance he consumed was at all intoxicating, I see no principled way to allow

3
the victim of a spiked drink to access the involuntary intoxication defense without
also sweeping in Mion. After all, the hypothetical person who consumes what
turns out to be a spiked drink wouldn’t necessarily know who made the drink or
what they or others secretly put in it, at a respectable licensed establishment or at
a house party with red Solo cups ripe for mischief.
¶59 And I’m also not convinced by the majority’s attempt to distinguish
between Mion and the hypothetical victim of a spiked drink through the Model
Penal Code’s reference to a possible fraud exception. Maj. op. ¶ 31. The majority
itself notes that because Colorado has codified the involuntary intoxication
defense, the common law is only persuasive. Id. at ¶ 14 n.4. And standing alone
as persuasive authority, the commentary to a tentative draft of model legislation
written in 1959 is thin gruel.
¶60 Nor do I understand what statutory “defense” the majority believes that
hypothetical victim would plead to access the “introduced pursuant to . . .
circumstances that would afford a defense” exception under section 18-1-804(5).
Maj. op. ¶ 29. Duress? In both cases (Mion’s and the hypothetical victim’s), the
defendants would be stretching the language of “the use or threatened use of
unlawful force upon him” to plead duress. § 18-1-708, C.R.S. (2025). And there is
no statutory language in section 18-1-804(5) that would immunize the victim of a

4
crime like assault unless they could also independently plead an affirmative
defense.
¶61 Finally, although I share the majority’s concern about opening the
floodgates to specious involuntary intoxication defenses, I take some comfort in
age-old tests of veracity. To justify instruction, a claim of innocent mistake must
be credible. Galvan, ¶ 24, 476 P.3d at 754 (“[T]he defendant, to raise the issue, shall
present some credible evidence on that issue.” (quoting § 18-1-407(1), C.R.S. (2025))).
The circumstances of Mion’s case—in which he testified on his own behalf and
police officers at least indirectly corroborated some of his testimony—were
unusual. Other defendants hoping for a similar safe harbor would struggle to
make the requisite threshold showing, and trial judges would continue to be
discerning in deciding whether they have done so. And even defendants who
manage to clear that admittedly low hurdle would still need to survive a jury’s
scrutiny.
¶62 Because I think the division got this right, I respectfully dissent.