Estate of O'Neill

#30969-r-MES
2026 S.D. 1

IN THE SUPREME COURT
OF THE
STATE OF SOUTH DAKOTA

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IN THE MATTER OF THE
ESTATE OF JUDITH ANN O’NEILL,
Deceased.

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APPEAL FROM THE CIRCUIT COURT OF
THE SIXTH JUDICIAL CIRCUIT
TODD COUNTY, SOUTH DAKOTA

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THE HONORABLE BOBBI J. RANK
Judge

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MICHAEL V. WHEELER of
DeMersseman Jensen Tellinghuisen
& Huffman, LLP
Rapid City, South Dakota

JAMES G. SWORD
Hot Springs, South Dakota Attorneys for appellant James
Anthony O’Neill.

CLINT SARGENT of
Meierhenry Sargent LLP
Sioux Falls, South Dakota

JAMES S. SIMKO of
Cadwell, Sanford, Deibert
& Garry LLP
Sioux Falls, South Dakota Attorneys for appellees Sandy
Lang, Beth O’Neill, and Richard
O’Neill.

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CONSIDERED ON BRIEFS
OCTOBER 7, 2025
OPINION FILED 01/07/26
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SALTER, Justice

[¶1.] James Anthony O’Neill (Tony), filed a petition for formal probate of his

mother’s last will and testament and a first codicil (collectively the Will) which left

her entire estate to Tony and specifically disinherited her other children. Tony’s

siblings filed an objection, asserting the Will was the product of undue influence. At

the trial of this undue influence claim, the circuit court relied upon the doctrine of

collateral estoppel to admit findings of fact and conclusions of law entered in a prior

civil case involving Tony and his brother, Richard O’Neill (Rick). The court also

instructed the jury that all of the previous findings and conclusions—including

adverse credibility determinations regarding Tony’s testimony—had been

conclusively established. The jury determined that Tony unduly influenced his

mother, and as a result, the Will was invalid. Tony appeals. We reverse and

remand for a new trial.

Factual and Procedural Background

[¶2.] Judith and Dean O’Neill were a married couple who farmed and

ranched in Bennett County and raised their four children, Tony, Rick, Sandy Lang,

and Beth O’Neill. When Tony and Rick became adults, they began their own

farming and ranching operation in the area, and the two brothers worked together

for a number of years.

[¶3.] But beginning in 2011, Tony and Rick began to separate their business

interests and their related real and personal property. As part of the effort, they

attempted to divide their property through written agreements. Eventually,

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however, there was a significant amount of conflict as to the effect and

enforceability of the agreements.

[¶4.] In order to resolve their differences and complete the division of the

two brothers’ property, Tony sought judicial intervention and commenced a civil

action in Bennett County (the prior action). The prior action was tried to the court

in July 2013, and, simply put, Tony lost badly on all issues. The court enforced both

a land separation agreement and an asset separation agreement and divided the

remaining assets in a way that resulted in Rick receiving more property than Tony,

in part, Rick later explained, because Tony had drafted the agreements unwisely.

[¶5.] The court in the prior action entered comprehensive written findings of

fact and conclusions of law related to the brothers’ business dealings and property.

Among these were discrete findings and conclusions about the land separation

agreement, including allegations that Rick forged Tony’s signature and claims that

Tony surreptitiously listed the brothers’ farm and cattle businesses as collateral on

loans for Tony’s own separate ventures.

[¶6.] In connection with its resolution of these issues contrary to Tony’s

positions, the prior court made multiple adverse credibility determinations in which

it found Tony’s version of particular facts relating to his dealings with Rick or their

farming and ranching business were “not credible.” In addition, the prior court

made other findings concerning Tony’s conduct vis-à-vis Rick that were highly

unfavorable, including the following pointed critique:

Tony’s strategy in dealing with Rick has been one of dishonesty
and malicious mischief. Tony was not honest with Rick before
this lawsuit, and during this lawsuit, in the handling of the
corporate financing. In addition, Tony committed fraud on this

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court by lying about the existence of a signed Land Separation
Agreement. . . . Tony was also not honest with this court when
he denied the existence of the negotiated agreement reached
between the parties.1

[¶7.] Seemingly unrelated to her sons’ business dispute, Judith had grown

weary of Dean’s mistreatment, which she stated included years of verbal and

physical abuse. In 2013, she moved from the family’s farm to Rapid City, and she

commenced a divorce action in 2014. During the pendency of the divorce, Judith

executed her Will on August 26, 2016, leaving to Tony 100% of her interest in all

the real estate she and Dean owned. Judith also stated in her Will, “It is my

specific request that Tony receive the family ranch home place upon my death.”

She left the remainder of her estate to Tony and her daughter Sandy, in equal

shares.

[¶8.] As explained by her former divorce lawyers during their testimony in

the undue influence trial, Judith’s effort to obtain a divorce was protracted. She

believed the reason was, at least in part, attributable to delay tactics orchestrated

by Dean. As time went by, Judith also attributed some of the blame to Sandy, who

sought a conservatorship for Judith only days before the scheduled divorce trial.

Judith and Dean ultimately settled their divorce in April 2018, and the resulting

decree required Dean to make an equalization payment to Judith in the amount of

$605,000.

1. Tony appealed the judgment in the prior action, and we affirmed it in a
published decision, with the exception of a punitive damage award imposed
against Tony, which we vacated. See O’Neill v. O’Neill, 2016 S.D. 15, 876
N.W.2d 486.

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[¶9.] Prior to this, though, Judith executed the first codicil to the Will on

July 26, 2017, which removed Sandy from her estate plan. Under the first codicil,

Judith left all her real estate, as well as the entirety of the remainder of her estate,

to Tony and excluded her other children by stating, “As it relates to Richard O’Neill,

Beth O’Neill, and Sandy Lang f/n/a [sic] Sandy O’Neill, they are specifically and

intentionally omitted form [sic] this Will and shall not receive anything from my

Estate.”

[¶10.] Judith died on November 28, 2018, and Tony filed a petition for formal

probate of the Will on March 20, 2019. His siblings—Rick, Sandy, and Beth (the

Respondents)—filed an objection, alleging that Judith’s Will was the product of

undue influence, lack of capacity, fraud, duress, mistake, and revocation.

[¶11.] Prior to the undue influence trial, the Respondents moved for an order

declaring the factual findings from the prior action as conclusively established

pursuant to the doctrine of collateral estoppel. In their written submissions to the

circuit court, the Respondents described the prior action as “a tense, lengthy, and

deeply personal case that centered on document validity (partnership separation

agreements and land separation agreements) and fiduciary duties owed to the

brothers’ farm corporations.”

[¶12.] The Respondents alleged a relationship between the outcome of the

prior litigation involving business issues between Tony and Rick and the undue

influence case, but more in terms of a case theory—not particular common issues.

For instance, the Respondents claimed that the prior litigation left Tony in a

perilous financial condition which, in turn, led him to exert undue influence over

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Judith through deception about Rick. But, critically, the Respondents did not

identify particular issues from the prior litigation that were identical to the ones in

the undue influence case.

[¶13.] Rather, the effort by the Respondents to use collateral estoppel to

admit the findings and conclusions from the prior litigation seemed more of an

effort to establish an unflattering aspect of Tony’s conduct or character. They

claimed, in this regard, that “Tony’s conduct in his business separation with Rick,

Tony’s defiance of court orders and witness oaths, and Tony’s cascading financial

condition are all so blended and connected with the elements of undue influence

that [the prior court’s] findings are part of the res gestae of Tony’s overall scheme.”

(Emphasis added.)

[¶14.] Tony opposed the admission of the findings and conclusions on several

bases and maintained that credibility determinations were for the finder of fact in

the undue influence trial. And as it related to specific areas that the Respondents

believe were conclusively established by the prior action, Tony argued the

Respondents were required to “identify each finding of fact it would intend to offer

so that it may be properly scrutinized by the court and counsel prior to its use at

trial.”

[¶15.] The circuit court admitted nearly all of the findings and conclusions as

a trial exhibit that spanned 44 pages, excepting only a portion relating to a punitive

damage award we reversed on appeal.2 See supra n.1. The court concluded en

2. The circuit court also admitted a six-page order reflecting the division of the
land and assets between Tony and Rick, as well as a subsequently entered,
(continued . . .)
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masse “that the elements of issue preclusion have been met with respect to the

foregoing findings and conclusions” and that the Respondents were “not required to

put on evidence to re-litigate any of those issues, nor can Tony O’Neill re-litigate

any of those issues.” However, the court ordered that the prior action findings and

conclusions were subject to other evidentiary challenges such as relevancy. The

court ordered Tony to raise any such “additional evidentiary objections . . . in

writing and identified by paragraph number with appropriate authority supporting

the objection[.]”

[¶16.] Although the undue influence trial was rescheduled several times,

Tony never submitted written objections to further challenge the admission of the

findings and conclusions other than the objections he identified initially. Tony’s

counsel renewed those objections prior to the beginning of the undue influence trial

and again during Tony’s testimony.

[¶17.] The prior action findings and conclusions featured prominently in the

Respondents’ case during the undue influence trial. However, the findings and

conclusions were used principally as a means of reopening specific collateral topics

related to the brothers’ prior business dealings and then juxtaposing Tony’s

discredited views of the underlying facts against the prior court’s adverse findings

relating to his credibility and conduct. The following exchange between the

Respondents’ counsel and Tony is emblematic:

________________________
(. . . continued)
three-page contempt order that included the finding that “Tony is . . . guilty
of [c]ontempt of [c]ourt for failure to comply with the [c]ourt’s [o]rder.”

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Counsel: So in Finding of Fact 39, [the prior court] states,
Rick made a copy of the written agreement signed
by both he and Tony. A copy of the Land
Separation Agreement is Exhibit C. Tony’s
testimony to the contrary is not credible.

Again, you’re disputing that still today?

Tony: I don’t agree with it but I’ve learned to live with it.

Counsel: Finding of fact 40, the judge found that Tony took
the original of Exhibit C with him at the conclusion
of the meeting. Tony’s testimony to the contrary is
not credible.

Again, you’re disputing that you took the original
with you that day?

Tony: I don’t agree with it but I’ve learned to live with it.

[¶18.] The circuit court later instructed the jury that they were to consider

the findings and conclusions as “conclusively established facts that you must accept

as true. Such findings and conclusions carry the same weight as all the evidence

you heard in this trial.”

[¶19.] The jury ultimately determined that Judith’s Will was invalid due to

Tony’s undue influence of Judith. Tony appeals, asserting that the circuit court

erred when it admitted the findings of fact and conclusions of law from the prior

action.

Analysis and Decision

Collateral Estoppel

[¶20.] Collateral estoppel, also known as issue preclusion, is one of two

preclusion concepts encompassed by the doctrine of res judicata. Healy Ranch, Inc.

v. Healy, 2022 S.D. 43, ¶ 40, 978 N.W.2d 786, 798. The first type—issue

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preclusion—“refers to the effect of a judgment in foreclosing relitigation of a matter

that has been litigated and decided.” Id. (citation omitted).

[¶21.] The second type of res judicata, known as claim preclusion, is broader

than issue preclusion and “refers to the effect of a judgment in foreclosing litigation

of a matter that never has been litigated, because of a determination that it should

have been advanced in an earlier suit[.]” Id. (alteration in original) (citation

omitted). Here, we are concerned only with issue preclusion, which when

applicable, prevents relitigation of issues actually litigated in a prior proceeding.

Id. ¶ 41.

[¶22.] We noted in Mendenhall v. Swanson, that principles of issue preclusion

can apply to prior factual findings, explaining:

Under the judicially-developed doctrine of [issue preclusion],
once a court has decided an issue of fact or law necessary to its
judgment, that decision is conclusive in a subsequent suit based
on a different cause of action involving a party to the prior
litigation. . . . This doctrine relieve[s] parties of the cost and
vexation of multiple lawsuits, conserve[s] judicial resources,
and, by preventing inconsistent decisions, encourage[s] reliance
on adjudication. . . . A party may invoke issue preclusion either
offensively or defensively.

2017 S.D. 2, ¶ 10, 889 N.W.2d 416, 419–20 (internal citations omitted) (emphasis

added).

[¶23.] Despite its utility, collateral estoppel may not lead to the preclusion of

all facts in all subsequent cases; rather, it “bar[s] relitigation of an essential fact or

issue involved in the earlier suit” and only if a four-part test is satisfied:

(1) Was the issue decided in the prior adjudication identical with
the one presented in the action in question? (2) Was there a final
judgment on the merits? (3) Was the party against whom the
plea is asserted a party or in privity with a party to the prior

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adjudication? (4) Did the party against whom the plea is
asserted have a full and fair opportunity to litigate the issue in
the prior adjudication?

Hamilton v. Sommers, 2014 S.D. 76, ¶ 34, 855 N.W.2d 855, 866 (alteration in

original) (citation omitted) (emphasis added).

[¶24.] The challenge in this appeal implicates two particular collateral

estoppel rules. The first, from the four-part test set out in Hamilton, requires us to

consider whether the factual issues decided in the prior action relating to the

division of farmland and assets between Tony and Rick are identical to those

presented in the undue influence trial. And, second, as a fundamental requirement

of collateral estoppel, we must consider whether the prior court’s adverse credibility

determinations relating to Tony’s testimony were essential to its judgment. “We

review a circuit court’s application of collateral estoppel de novo.” Id. (citation

omitted).3

1. Identical issues.

[¶25.] Tony maintains in this appeal that because the dispositive issues in

the prior case and the present case are not identical, the circuit court erroneously

applied collateral estoppel to the prior action findings and conclusions. The

Respondents claim that Tony’s conduct toward Rick as related in the findings and

conclusions in the prior action, his defiance of court orders in the prior action, and

3. In his appellate brief, Tony views the issue of admission of the findings and
conclusions from the prior action as an evidentiary ruling to be reviewed
under our abuse of discretion standard. But the fundamental issue presented
here is whether the circuit court correctly applied collateral estoppel
principles—a legal issue we review de novo.

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his failing financial condition were all so blended and connected with the elements

of undue influence that the issues in the two actions are identical.

[¶26.] We believe that the comparison the Respondents make between the

two cases is more figurative, or thematic, than literal. The claims addressed in the

prior action are much different than those in the undue influence action, and the

constituent factual issues are not identical. Indeed, the Respondents have not

identified the existence of any discrete issues that were litigated to completion in

the prior action that were identical to those presented in the undue influence trial.

See Madalena v. Zurich Am. Ins. Co., 532 P.3d 776, 783 (Colo. Ct. App. 2023) (“An

‘issue’ may be one of evidentiary fact, ultimate fact, or law.”) (citing Restatement

(Second) of Judgments § 27 cmt. c).

[¶27.] As the undue influence litigation played out, it appears the

Respondents sought to apply collateral estoppel to allow “factual findings” from the

prior court, not so much to establish distinct facts about the merits of the prior

action, but to support their assertion that Tony was not credible, had not followed

the court’s orders, and had mistreated Rick. In this way, the findings were part of a

broader theory of the case for the Respondents, as explained by their counsel in his

brief on the collateral estoppel issue:

Starting in the summer of 2011, Tony set upon a scheme to bully
his brother/business partner and gain financial advantage over
him. Even before Tony commenced litigation against Rick, Tony
portrayed himself to his mother as the victim. Tony convinced
his mother that Rick was getting an unfair split of the
partnership assets and that Dean had completely sided with
Rick. Tony convinced Judith that Dean would disinherit Tony
when Dean died. Tony convinced his mom that Rick has
convinced his dad to disinherit Tony. Many of these facts were
previously litigated and found to be untrue by [the prior court].

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However, Tony’s allegations of Rick and Dean’s conspiring
against Tony were effective in convincing Judith to divorce Dean
and to eventually disinherit all of her children and
grandchildren except Tony.

[¶28.] Despite counsel’s statement that “many of these facts . . . were found to

be untrue,” the prior court did not determine whether Tony had lied to his mother

or tried to unduly influence her. The factual issues that were litigated in the prior

action were simply not identical to those in the undue influence trial, which is not

surprising given the vastly different nature of the two actions. The prior action was

an effort to divide land and assets between Tony and Rick as former business

partners; the undue influence case, predictably, featured different factual issues

relating to Tony’s conduct and alleged deception relating to Judith, not Rick.

[¶29.] The Respondents appear to argue that Tony’s credibility or his

duplicity, or both, were central issues pervading both cases, such that the credibility

and misconduct findings from the prior action could be conclusive in the undue

influence action. But this looks less like collateral estoppel and much more like

other acts evidence. See SDCL 19-19-404 (Rule 404) (providing that character

evidence is generally not admissible subject to certain exceptions). In fact, the

Respondents have alluded, at various points in the case, to the evidentiary concept

of res gestae—or intrinsic evidence—which is often associated with other acts

evidence. See State v. Stark, 2011 S.D. 46, ¶ 25, 802 N.W.2d 165, 173

(distinguishing between res gestae and other acts evidence under Rule 404(b)). This

excerpt from the Respondents’ brief to the circuit court illustrates the point:

Tony’s conduct in his business separation with Rick, Tony’s
defiance of court orders and witness oaths, and Tony’s cascading
financial condition are all so blended and connected with the

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elements of undue influence that [the prior court’s] findings are
part of the res gestae of Tony’s overall scheme.

[¶30.] However, the circuit court admitted the prior action findings and

conclusions under the doctrine of collateral estoppel—not res gestae or Rule 404.

And using collateral estoppel to conclusively establish credibility or litigation

misconduct issues from a prior action in a different later action is not sustainable.

2. Issues necessary or essential to the prior judgment.

[¶31.] In addition to erroneously determining widespread identity of issues

between the prior action and the undue influence case, the circuit court’s decision to

admit the prior action findings and conclusions also failed to account for the

fundamental design of the collateral estoppel doctrine—the findings were essential

to the prior judgment. See Mendenhall, 2017 S.D. 2, ¶ 10, 889 N.W.2d at 419–20

(holding that issue preclusion requires the prior findings or conclusions were

necessary or essential to the prior judgment); Hamilton, 2014 S.D. 76, ¶ 34, 855

N.W.2d at 866 (same). An issue was necessarily decided in an earlier action when it

was “actually litigated” and was “essential to the prior decision.” Riverwood Com.

Park, L.L.C. v. Standard Oil Co., Inc., 729 N.W.2d 101, 109 (N.D. 2007).

[¶32.] Here, when the circuit court adopted the findings and conclusions from

the prior action, it made a general finding that the four-part collateral estoppel test

from Hamilton was satisfied, but the court did not make specific findings on any of

the enumerated requirements, including whether the prior action findings and

conclusions were necessary or essential to the prior judgment. And from our review

of the findings and conclusions, most or all of what the Respondents sought to

establish through collateral estoppel were adverse credibility determinations

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concerning Tony, which were decidedly not necessary or essential to the prior

judgment.

[¶33.] The Louisiana Court of Appeals’ decision in Rao v. Rao, 927 So. 2d 356

(La. Ct. App. 2005), supports this conclusion. In Rao, the wife in a divorce action

argued that the trial court’s prior credibility determination on an unrelated issue—

fault for purposes of final spousal support—also supported her assertion that an

agreement was the product of a fraudulent scheme. Id. at 361. The wife argued

that the “trial court’s prior credibility determination in the context of resolving a

different legal issue affords her the benefit of issue preclusion under the doctrine of

collateral estoppel.” Id. The appellate court rejected the claim and explained:

While it is true that credibility is essentially a fact issue, it is not
generally the dispositive issue before the trier of fact, but rather a
preliminary issue or factor in the determination of the ultimate
dispositive issue. As one court has stated, “[i]ssue preclusion
requires the issue to be precluded to have been a dispositive
issue which the prior court must have considered in a contest
between the same parties.” It is well settled that in reaching its
conclusions, the trier of fact need not accept all of the testimony
of any witness as being true or false and may believe and accept
any part or parts of a witness’s testimony and refuse to accept
any other part or parts thereof.

Id. (citations omitted) (alteration and emphasis in original) (italics added).

[¶34.] We think this reasoning is sound. In this case, the prior court’s

credibility determinations relating to Tony were not necessary or essential to the

prior judgment. The court could have made the same determinations based simply

upon the relative weight of the evidence, even rejecting certain evidence without

holding, as it did, that Tony had been dishonest. Indeed, the credibility issues in

the prior action are so remote to the issues in this undue influence case that they

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created the not-so-subtle message that Tony was a liar in the undue influence case

because he had been found not credible in the prior action involving Rick.

[¶35.] Allowing the prior court’s credibility determinations to be used in this

preclusive way is inconsistent with the well-settled rule that credibility

determinations are exclusively within the province of the jury. Estate of Tank, 2023

S.D. 59, ¶ 47, 998 N.W.2d 109, 124 (noting “[i]t is within the province of the jury as

the ultimate trier of fact to weigh conflicting evidence and decide upon the

credibility of witnesses.”) (citation omitted); State v. Rouse, 2025 S.D. 29, ¶ 19, 23

N.W.3d 467, 474 (“The jury is the exclusive judge of the credibility of the

witnesses[.]” (citation omitted)); 75A Am. Jur. 2d Trial § 955 (“In charging the jury,

a trial judge may not interfere with the province of the jury in determining the

credibility of witnesses, and the trial court’s commenting on the witnesses’

credibility may constitute prejudicial error.”). For these reasons, the circuit court

incorrectly applied the principles of collateral estoppel, and we must consider

whether the error was prejudicial.4

4. The Respondents claim that because Tony did not file specific written
objections to particular findings as directed by the circuit court, “Tony has
waived his right to contest the admission of [the findings and conclusions] on
any basis other than the proper application of the doctrine of collateral
estoppel and issue preclusion.” But this argument suggests a distinction that
does not exist; the proper application of the collateral estoppel rules is the
issue Tony identifies on appeal. And as it relates to the prior court’s adverse
credibility findings in particular, Tony objected on the basis of relevance
which is contained within the collateral estoppel showing of identity of issues,
i.e., if the issues presented at the earlier and later actions are, indeed,
identical, evidence of the prior adjudication is not merely relevant to the later
one—it is the same thing. Cf. Megaro v. McCollum, 66 F.4th 151, 160 (4th
Cir. 2023) (collateral estoppel bars litigation of claims where four factors are
met, including that “the issues were material and relevant to the disposition
(continued . . .)
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Prejudice

[¶36.] We have recognized that the circuit court’s error in the application of

collateral estoppel “is subject to the harmless-error rule.” Mendenhall, 2017 S.D. 2,

¶ 13, 889 N.W.2d at 420–21 (court’s erroneous treatment of facts as conclusively

established analyzed for harmless error) (citing SDCL 15-6-61). Under this rule, “if

one cannot say, with fair assurance, after pondering all that happened without

stripping the erroneous action from the whole, that the judgment was not

substantially swayed by the error, it is impossible to conclude that substantial

rights were not affected.” Id. (citing Voorhees Cattle Co., LLP v. Dakota Feeding

Co., LLC, 2015 S.D. 68, ¶ 17, 868 N.W.2d 399, 408 (in determining whether

evidence admitted to conclusively prove issues at trial was reversible error, court

applied prejudicial error analysis, stating that error “is prejudicial if it ‘most likely

has had some effect on the verdict and harmed the [party’s] substantial rights.’”

(citation omitted))).

[¶37.] The credibility of the witnesses is important in all cases, but perhaps

particularly so in an undue influence case due to the nature of the evidence and

difficulty in defending against such a claim. As we have noted, in such cases, the

testator is not available to testify, the influence is not usually exercised in the open,

and there is often no direct proof of undue influence. In re Metz’ Estate, 100 N.W.2d

393, 397 (S.D. 1960); Thomas E. Simmons, Testamentary Incapacity, Undue

________________________
(. . . continued)
of the prior action”); Cent. Hudson Gas & Elec. Corp. v. Empresa Naviera
Santa S.A., 56 F.3d 359, 368 (2d Cir. 1995) (collateral estoppel test includes
requirement that “relevant issues were actually litigated and decided in the
prior proceeding”).

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Influence, and Insane Delusions, 60 S.D. L. Rev. 175, 203 (2015) (“Direct evidence of

undue influence is frequently unavailable because the testator is (obviously)

deceased, the wrongdoer cannot be expected to provide helpful testimony, and most

acts of undue influence occur in a private setting where the only observers were the

testator and the wrongdoer, one of whom is dead and the other uncooperative.”).

[¶38.] Further, proof of the claim relies almost entirely on inference—the

testator’s susceptibility to influence, the opportunity to exert influence, the

disposition to do so, and a result clearly showing the impact of influence. Estate of

Tank, 2020 S.D. 2, ¶ 33, 938 N.W.2d 449, 459. This is undoubtedly why Tony’s

credibility was the centerpiece of the Respondents’ case.

[¶39.] Indeed, Tony’s lack of credibility was the theme of much of opening

statement and closing argument of counsel for the Respondents. During his

opening statement, the Respondents’ counsel claimed that “Tony lied to his mom.

He cheated his brother. He committed fraud against his brother.” Counsel also

stated that the prior court concluded Tony was not credible and quoted portions of

the findings and conclusions relating to the prior court’s credibility determinations.

[¶40.] In his closing argument, counsel for the Respondents told jurors that

they must “conclusively accept” the findings and conclusions and, most significantly,

connect Tony’s credibility in the prior action to the current one by association—i.e.,

because Tony had not disavowed his former testimony relating to his business

dealings with Rick, he was lying in the undue influence case:

It is a fact you must accept. Tony lied in court. Tony tried to
defraud [the prior court]. . . . Now that’s relevant . . . to
instruction 14 where the Court says, if you believe that any
witness testifying in this case has knowingly sworn falsely to

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any material fact in this case, then you may reject all of the
testimony of the witness.

One of the first questions I asked Tony, do you stand by all of
the stuff that you told [the prior court] ten years ago. Right? I
gave him a chance to say no, she caught me. Right? I was lying
back then and I admit it, I apologize to Rick, I shouldn’t have
done that. But no, he’s here lying to you as well.

He’s still claiming that he believes Rick forged that document.
He’s still claiming that there was never a written signed
agreement between the two of them.

[¶41.] But this sort of heads-I-win/tails-you-lose argument represents a

disordered view of the credibility determination that the jury was required to make

in this case. In our view, the circuit court’s decision to admit the findings and

conclusions and then instruct the jury that they were conclusive proof very likely

had a massive impact on how the jury viewed Tony’s testimony.5 The jury was

effectively advised that Tony’s testimony was not credible, which we believe most

likely had an effect on and substantially swayed the verdict, and therefore, affected

Tony’s substantial rights. See Mendenhall, 2017 S.D. 2, ¶ 13, 889 N.W.2d at 420–

21; Vorhees, 2015 S.D. 68, ¶ 17, 868 N.W.2d at 408.

Conclusion

[¶42.] The circuit court erred in wholesale admitting findings of fact and

conclusions of law regarding issues that were not identical to issues in the present

case and not necessary or essential to the prior judgment. By then instructing the

5. The jury was instructed that Tony and his mother were in a confidential
relationship (Tony was Judith’s attorney in fact), and the circuit court further
instructed that if it found that Tony actively participated in the preparation
of Judith’s Will and he unduly profited therefrom, Tony bore the burden to
show he did not take unfair advantage of his mother.

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jury that all of the findings—including credibility determinations and specific

statements that Tony had been dishonest with Rick and the court—and instructing

the jury to consider those findings and conclusions as established, the court

effectively foreclosed the jury’s ability to undertake its own independent assessment

of the witnesses’ credibility on the issues more closely connected to the Respondents’

undue influence claim. We reverse and remand for a new trial.

[¶43.] JENSEN, Chief Justice, and DEVANEY, and MYREN, Justices, and

KERN, Retired Justice, concur.

[¶44.] GUSINSKY, Justice, not having been a member of the Court at the

time this action was considered by the Court, did not participate.

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