Guadalupe Lopez, Jr. applied for independent administration and an heirship determination after the death of his father, Guadalupe Lopez, Sr., and the county court declared Lopez Junior and his two siblings heirs of the estate.¹ Elvira Gonzalez then filed a petition for bill of review alleging that she was Lopez Senior's common-law wife and seeking a judgment declaring her an heir, and the trial court withheld ruling until a jury decided whether the two were informally married.² To prove the marriage, Gonzalez offered the videotaped deposition of Alicia York, a former district court judge, who told the jury over Lopez Junior's objections that Gonzalez "clearly . . . show[ed] that all three elements of common-law marriage existed".³ The trial evidence on an agreement to marry conflicted: Gonzalez offered photos of Lopez Senior wearing a wedding ring, quinceañera invitations calling them "Mr. & Mrs. Lupe Lopez," and a tax form and warranty deed identifying them as married, while the record also showed no joint bank account, tax, employment, and insurance documents listing them as "single," and testimony that Lopez Senior called another woman his "fiancée".⁴

The jury found that Lopez Senior and Gonzalez were married, and the trial court granted the bill of review and awarded Gonzalez a share of the estate.¹ The Fourth Court of Appeals in San Antonio affirmed without deciding whether admitting the testimony was error, holding any error harmless because the testimony was cumulative, articulated no improper legal concepts, was not emphasized, and the other evidence withstood a factual-sufficiency challenge.² Lopez Junior petitioned for review on May 20, 2024; the Court requested merits briefing, and decided the case per curiam on November 7, 2025, without oral argument.³

Petition for review from the Fourth Court of Appeals after a jury trial on a bill of review; granted and decided per curiam without oral argument under Rule of Appellate Procedure 59.1.⁴

Lopez Junior presents two issues: whether a retired family-law judge's testimony on legal standards and on whether the couple was informally married should have been excluded and its admission requires a new trial, and whether the statutory presumption of non-marriage applied because the couple stopped living together and no proceeding was brought within two years; the petition labeled the second issue unbriefed.¹ Gonzalez frames the issue as whether any error in admitting the testimony was harmful, given other evidence of the marriage, and whether the presumption required a separate jury question.² The Court decided only whether admitting the testimony was error and whether it was harmful.³

The Court reviews a trial court's admission of evidence for abuse of discretion.¹ Erroneous admission of expert testimony is harmless unless the error probably caused rendition of an improper judgment, meaning it contributed in a substantial way to the adverse judgment, and the Court evaluates the entire case from voir dire to closing argument.²

Whether the former judge's testimony was admissible.

Petitioner (Lopez Junior): Expert testimony is appropriate only when it helps the jury with specialized knowledge, but in informal-marriage cases the evidence is within the average juror's knowledge, an expert may not explain the law to the jury, and the jury should have been left to decide for itself and not instructed how to vote by someone clothed with judicial authority.¹ He also argues that York used evidence of cohabitation and holding out as evidence of an agreement to be married, contrary to Russell.²

Respondent (Gonzalez): She does not significantly contest that admitting the testimony was erroneous, according to Lopez Junior's reply, and she argues that the testimony was at best cumulative of the other evidence of the marriage.³ The Court observed that she offered no argument why specialized knowledge was needed to decide whether an informal marriage existed.⁴

Whether any error was harmful.

Respondent (Gonzalez): Even without York's testimony, the record proved every element of the informal marriage "by a comfortable margin," so any error was harmless; Lopez Junior must show that the judgment turns on the particular evidence admitted.⁵ She also argues that a rebuttable presumption merely assigns a burden of production and vanishes once rebutted, so no separate jury question was required.⁶

Petitioner (Lopez Junior): The testimony was the sole support for a key element of the claim, and nothing in the documentary evidence actually showed an agreement to be married, which cannot be inferred from cohabitation and holding out.⁷

The petition has no separate statement of reasons for review; its summary argued that expert testimony helps the jury only with specialized knowledge, which informal-marriage evidence does not require, and that York's testimony usurped the judge's role.¹ Gonzalez responded that review should be denied because the court of appeals correctly found any error harmless without suggesting that an expert like York could testify in another case.²

None. The docket shows no amicus filings.

Holding

The trial court abused its discretion by admitting the former judge's expert testimony, which was within jurors' common knowledge, improperly opined on a legal presumption, and told the jury how she would rule as judge; the error was harmful, so a new trial is required. The Court did not hold that former judges may never testify as experts.¹

Reasoning

Error. Expert testimony helps the jury only if the expert's knowledge is beyond the average juror's, and a trial court should exclude it when the jury is equally competent to form an opinion or the matter is within common knowledge.² The elements of an informal marriage under Family Code section 2.401(a)(2), an agreement to be married, living together as spouses, and representing to others that they were married, are not specialized or beyond an ordinary juror's understanding.³ To the extent York offered anything specialized, it was impermissible testimony about the law, including at length about a Family Code presumption, which is the court's role and not the witness's, and her testimony served only to give "an official endorsement" of Gonzalez's position, with York stressing that she formed her opinions "wearing [her] judge's hat".⁴ The Court cautioned that former judges are not categorically barred from testifying as experts, for example on the reasonableness of attorney's fees, but that parties should avoid repeatedly touting the status.⁵

Harm. All the relevant factors pointed to harm.⁶ York's testimony was crucial to the only contested issue, on which the evidence cut both ways, so the jury likely relied on her opinion.⁷ The testimony was not cumulative, because it gave her own spin on how to weigh competing evidence and she was the only expert on the issue.⁸ Gonzalez's use of it was calculated, not inadvertent, and the testimony was emphasized by introducing York as a former family-law judge and keeping that role in view.⁹

Disposition

Without hearing oral argument, the Court granted the petition for review, reversed the court of appeals' judgment, and remanded to the trial court for a new trial.¹⁰

Vote Breakdown

Per Curiam Opinion

Joined by Blacklock, C.J., and Bland, Busby, Devine, Hawkins, Huddle, Sullivan, and Young, JJ.

Did Not Participate

Lehrmann, J.