In Re Estate of Guadalupe Lopez, Sr.

Supreme Court of Texas
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No. 24-0315
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In re Estate of Guadalupe Lopez, Sr., Deceased

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On Petition for Review from the
Court of Appeals for the Fourth District of Texas
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PER CURIAM

Justice Lehrmann did not participate in the decision.

“[T]he expert witness paints a powerful image on the litigation
canvas,” possessing a “vast potential for influence.” In re Christus
Spohn Hosp. Kleberg, 222 S.W.3d 434, 440 (Tex. 2007). The expert in
this case is a former family court judge who opined on the central
disputed issue in the case, testifying before the jury that, in her view,
the parties were informally married. She expressed that opinion
repeatedly and emphatically, though none of the relevant evidence was
technical, specialized, or otherwise beyond an ordinary person’s
understanding. Compounding the problem, she lent her opinion
credibility by explaining that she formed it using the same methodology
she employed when she presided over informal-marriage cases as a
judge. Unsurprisingly, the jury was persuaded and found an informal
marriage existed.
We hold that the trial court erred in admitting the expert’s
testimony and that the error was harmful, warranting a new trial. The
evidence was within the average juror’s common knowledge, so the
expert’s opinions did not help the jury as Rule of Evidence 702
contemplates. See TEX. R. EVID. 702. The expert instead improperly
opined on a legal presumption and explained that, if she were sitting as
the judge, she would find that the parties were informally married.
Mindful that the appearance of a judge as a witness carries the potential
both to sway the jury improperly and to “threaten[] . . . public confidence
in the integrity and impartiality of the judiciary,” Joachim v. Chambers,
815 S.W.2d 234, 238 (Tex. 1991) (quotation marks omitted), we conclude
that admitting this testimony amounted to harmful error. Accordingly,
we reverse the court of appeals’ judgment and remand the case to the
trial court for a new trial.
I
Guadalupe Lopez, Jr. (Lopez Junior) applied for independent
administration and an heirship determination after the death of his
father, Guadalupe Lopez, Sr. (Lopez Senior). The county court granted
the application and rendered judgment declaring Lopez Junior and his
two siblings heirs of their father’s estate. Elvira Gonzalez later filed a
petition for bill of review, alleging she was Lopez Senior’s common-law
wife and seeking a judgment declaring her an heir.
The trial court withheld ruling on the bill of review until after a
jury determined whether Lopez Senior and Gonzalez were informally
married. To support her claim that they were, Gonzalez offered the
expert testimony of Alicia York, a former district court judge. Over

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Lopez Junior’s objections, the trial court admitted Judge York’s
videotaped deposition testimony in which she told the jury that
Gonzalez “clearly . . . show[ed] that all three elements of common-law
marriage existed.” The jury found that Lopez Senior and Gonzalez were
married, and the trial court rendered judgment granting the bill of
review and awarding Gonzalez a share of Lopez Senior’s estate.
Lopez Junior appealed, challenging, among other things, the
admission of Judge York’s testimony. The court of appeals affirmed. ___
S.W.3d ___, 2024 WL 946236, at *1 (Tex. App.—San Antonio Mar. 6,
2024). The court did not decide whether the trial court abused its
discretion in admitting Judge York’s testimony. It instead offered four
reasons why any error was harmless: (1) the testimony was cumulative;
(2) none of Judge York’s opinions “articulated improper legal concepts”;
(3) Gonzalez did not emphasize Judge York’s testimony; and (4) the
other evidence supporting Gonzalez’s claim comfortably “withstood
Lopez Junior’s factual sufficiency challenge.” Id. at *9-10.
Lopez Junior petitioned this Court for review.
II
We review a trial court’s admission of evidence for an abuse of
discretion. Serv. Corp. Int’l v. Guerra, 348 S.W.3d 221, 235 (Tex. 2011);
In re J.P.B., 180 S.W.3d 570, 575 (Tex. 2005). A qualified expert may
testify if their “specialized knowledge will help the trier of fact to
understand the evidence or to determine a fact in issue.” TEX. R.
EVID. 702. Because an expert’s testimony does not help the jury unless
“the expert’s knowledge and experience on a relevant issue are beyond
that of the average juror,” K-Mart Corp. v. Honeycutt, 24 S.W.3d 357,

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360 (Tex. 2000), a trial court should exclude an expert’s testimony
“[w]hen the jury is equally competent to form an opinion about the
ultimate fact issues or the expert’s testimony is within the common
knowledge of the jury,” id.; cf. Guevara v. Ferrer, 247 S.W.3d 662, 665
(Tex. 2007) (“The general rule has long been that expert testimony is
necessary to establish causation as to medical conditions outside the
common knowledge and experience of jurors.”). If expert testimony is
unhelpful, it is inadmissible, and the trial court errs by allowing it. See
Dall. Morning News, Inc. v. Hall, 579 S.W.3d 370, 379 (Tex. 2019).
Erroneous admission of expert testimony is harmless—and thus
not grounds for reversal—“unless the error probably (though not
necessarily) caused rendition of an improper judgment.” Reliance Steel
& Aluminum Co. v. Sevcik, 267 S.W.3d 867, 871 (Tex. 2008); see TEX. R.
APP. P. 61.1(a). An error is harmful if it “contributed in a substantial
way to bring about the adverse judgment.” Gunn v. McCoy, 554 S.W.3d
645, 668 (Tex. 2018) (quoting Lorusso v. Members Mut. Ins. Co., 603
S.W.2d 818, 820 (Tex. 1980)). Admission of improper evidence can be
harmful even if there is other legally sufficient evidence supporting the
verdict. See Kia Motors Corp. v. Ruiz, 432 S.W.3d 865, 884 (Tex. 2014).
To determine whether the error is harmful, “we evaluate the
entire case from voir dire to closing argument, considering the evidence,
strengths and weaknesses of the case, and the verdict.” Guerra, 348
S.W.3d at 236. Relevant factors include “the role the evidence played in
the context of the trial,” Sevcik, 267 S.W.3d at 873, “whether counsel
emphasized the erroneous evidence,” Guerra, 348 S.W.3d at 236,
“whether the admission of the evidence was calculated or inadvertent,”

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id., and “whether contrary evidence existed that the improperly
admitted evidence was calculated to overcome,” U-Haul Int’l, Inc. v.
Waldrip, 380 S.W.3d 118, 136 (Tex. 2012). The error is likely harmless
if the admitted evidence was cumulative “or if the rest of the evidence
was so one-sided that the error likely made no difference.” Sevcik, 267
S.W.3d at 873. By contrast, the error is likely harmful if the evidence
“was crucial to a key issue.” Id. See generally Jackson v. Takara, 675
S.W.3d 1, 6-7 (Tex. 2023); In re Est. of Poe, 648 S.W.3d 277, 285-86 (Tex.
2022); Caffe Ribs, Inc. v. State, 487 S.W.3d 137, 145 (Tex. 2016).
III
It was error to admit Judge York’s expert testimony. The issue
on which she opined—whether the evidence established an informal
marriage—was within the average juror’s knowledge. See TEX. R.
EVID. 702; K-Mart, 24 S.W.3d at 360 (“When the jury is equally
competent to form an opinion about the ultimate fact issues or the
expert’s testimony is within the common knowledge of the jury, the trial
court should exclude the expert’s testimony.”). The elements needed to
prove an informal marriage—that the couple agreed to be married, lived
together as husband and wife after the agreement, and represented to
others that they were married, see TEX. FAM. CODE § 2.401(a)(2)—are
not specialized or otherwise beyond the understanding of an ordinary
juror. Gonzalez notably makes no argument as to why “specialized
knowledge,” TEX. R. EVID. 702, is necessary to determine whether the
evidence shows an informal marriage existed. See Dall. Morning News,
579 S.W.3d at 379.

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To the extent Judge York offered insights that could be regarded
as specialized or beyond common knowledge, it was in the form of
impermissible testimony about the law. See In re Ayad, 655 S.W.3d 285,
288 n.1 (Tex. 2022); TEX. R. EVID. 702-704. For example, Judge York
testified at length about a Family Code presumption and how the jury
should apply it when reviewing the evidence. It is the trial court’s role—
not that of the expert witness—“to define the particular legal principles
applicable to a case.” Greenberg Traurig of N.Y., P.C. v. Moody, 161
S.W.3d 56, 95 (Tex. App.—Houston [14th Dist.] 2004, no pet.); see also
id. at 99 (“By permitting attorneys to state opinions as to what the
applicable law is, the trial judge voluntarily allows his role as the legal
expert in the courtroom to be usurped or diminished by the testifying
attorney.”).
Rather than help the jury understand subject matter beyond
common knowledge, Judge York’s testimony served only the improper
purpose of providing “an official endorsement” favoring Gonzalez’s
position. See Joachim, 815 S.W.2d at 238. She emphasized that she
formed her opinions “wearing [her] judge’s hat” and explained that on
the evidence presented, based on her experience presiding over 5,000
family-law trials, Gonzalez should win. The trial court thus erred in
admitting Judge York’s testimony.1

1 While courts must be mindful of the unique concerns that arise when

a former judge testifies as an expert witness, see Joachim, 815 S.W.2d at 239,
we do not hold that former judges are categorically prohibited from testifying
as experts. For example, testifying about the reasonableness of a party’s claim
for attorney’s fees is a proper subject for expert testimony and does not subject
the jury to the expert’s judicial views to the extent that the testimony here did.
But even in cases in which a former judge’s expert testimony is admissible,

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We also conclude that the error was harmful—that it “contributed
in a substantial way to bring about the adverse judgment.” Gunn, 554
S.W.3d at 668 (quoting Lorusso, 603 S.W.2d at 820). Indeed, all the
relevant factors in the harm analysis point toward this conclusion.
First, Judge York’s testimony was crucial to the only contested
issue in the case, on which the evidence cut both ways. See Sevcik, 267
S.W.3d at 873 (“[I]f erroneously admitted . . . evidence was crucial to a
key issue, the error was likely harmful.”). While there is evidence in the
record from which the jury could have found an agreement to be
married—for example, photos of Lopez Senior wearing a wedding ring,
two quinceañera invitations for Gonzalez’s daughters identifying Lopez
Senior and Gonzalez as “Mr. & Mrs. Lupe Lopez,” and a tax form and
warranty deed identifying them as married—the record also contains
contrary evidence. For example, Lopez Senior and Gonzalez never had
a joint bank account, and documentary evidence (tax forms, employment
records, and car insurance) showed they identified themselves as
“single.” And there was testimony that Lopez Senior referred to another
woman as his “fiancée” during the time Gonzalez claimed to be his wife.
It is thus far from clear whether the jury would have found an
agreement absent Judge York’s testimony as to how she would have
weighed the competing evidence in her capacity as a judge. The fact that
the evidence was not one-sided makes it more likely the jury relied on

trial courts, counsel, and the witness should avoid repeated touting and
emphasis of the expert’s status as a former judge of the sort apparent in this
record. See id. (“The entrance of a judge into the litigation arena in aid of a
combatant impacts not only the outcome of that conflict but the very idea of
judicial impartiality.”).

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her opinion in reaching its verdict. See Christus Spohn Hosp., 222
S.W.3d at 440 (“[T]he expert is generally held out to be, and is seen by
the jury as, an objective authority figure more knowledgeable and
credible than the typical lay witness.”).
Second, we disagree with the court of appeals’ conclusion that
much of Judge York’s testimony was cumulative. See 2024 WL 946236,
at *9. Her testimony did more than merely restate or summarize the
evidence—she provided her own spin on how the jury should weigh
competing evidence on the only issue it was asked to decide. Cf. Bagheri
v. State, 119 S.W.3d 755, 763-64 (Tex. Crim. App. 2003) (concluding that
the effect of an expert’s testimony regarding a defendant’s intoxication
“was almost certainly to tip the balance in favor of the State,” so the
expert’s erroneously admitted testimony was not cumulative despite
other evidence that the defendant was intoxicated). Judge York was the
only expert to testify on the informal-marriage issue. See State v.
Dawmar Partners, Ltd., 267 S.W.3d 875, 881 (Tex. 2008) (concluding
that the challenged experts’ testimony “was cumulative of substantially
similar [testimony] from another expert”); Mancorp, Inc. v. Culpepper,
802 S.W.2d 226, 230 (Tex. 1990) (concluding that the challenged expert’s
testimony was cumulative of similar testimony from six other experts).
Nor is this a case where “an abundance of evidence” otherwise supports
the finding the expert advanced. GTE Sw., Inc. v. Bruce, 998 S.W.2d
605, 620 (Tex. 1999); see also Sevcik, 267 S.W.3d at 873 (noting that the
erroneous admission of evidence is likely harmless if “the rest of the
evidence was so one-sided that the error likely made no difference”). As

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detailed above, the evidence conflicted, and Judge York told the jury that
Gonzalez should win.
Third, Gonzalez’s use of Judge York’s testimony was “calculated,”
not “inadvertent.” Sevcik, 267 S.W.3d at 874; see also U-Haul Int’l, 380
S.W.3d at 136 (“[Plaintiff]’s advocacy for inclusion of this testimony, over
objection, suggests it was a significant element of this case.”); Sevcik,
267 S.W.3d at 874 (“[A] party’s insistence on introducing inadmissible
testimony ‘indicates how important he thought it was to his case.’”
(quoting Alvarado v. Farah Mfg. Co., 830 S.W.2d 911, 917 (Tex. 1992))).
Finally, we disagree with the court of appeals and Gonzalez that
the evidence was not emphasized. See 2024 WL 946236, at *10. We
have previously rejected arguments that prejudicial evidence was
harmless merely because it was mentioned only once, observing “[i]f that
were the only rule, there would be little use for the rules of evidence as
everyone could ignore them once with impunity.” Sevcik, 267 S.W.3d at
873-74. Here, Judge York was introduced to the jury as a former
family-law judge, and that role was emphasized throughout her
testimony.
IV
The trial court abused its discretion by admitting the testimony
of a former judge as an expert witness when (1) the expert’s opinion was
not beyond common knowledge and therefore did not help the jury as
Rule of Evidence 702 contemplates and (2) the expert emphasized that
her opinion was the finding she would make if she were the judge in this
case. The error was harmful because the improperly admitted evidence
was not cumulative and the ultimate issue for the jury was hotly

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contested, with the parties offering sharply conflicting evidence in
support of their respective positions. Accordingly, without hearing oral
argument, we grant the petition for review, reverse the court of appeals’
judgment, and remand the case to the trial court for a new trial. See
TEX. R. APP. P. 59.1.

OPINION DELIVERED: November 7, 2025

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