In Whitton v. Dixon, No. 25-580 (June 1, 2026) (per curiam), the Supreme Court held that in federal habeas proceedings, a court cannot consider post-trial evidence that the jury never saw when evaluating whether a constitutional trial error (like the use of false testimony) was harmless. The ruling dictates that prejudice under harmless-error review must be assessed exclusively based on the evidence that was part of the original trial record.
Gary Whitton was convicted and sentenced to death by a Florida jury. During his trial, the state presented the testimony of jail house informant Jake Ozio, who had been arrested and jailed for burglary and possession of a sawed-off shotgun while on spring break. Ozio testified that while he was incarcerated, he overheard Whitton confess to “stabb[ing] the bastard.” Ozio also testified that he had no prior criminal history, except for his spring break arrest. That last piece of testimony turned out to be false. Ozio’s juvenile records—which the State had in its possession at the time—showed that he had previously been charged with “assault with bodily injury against his father, terroristic threats against his mother, and at least one other burglary.”
After unsuccessfully pursuing direct appeal and state postconviction, Whitton filed a petition for federal habeas corpus relief alleging, among other claims, that Ozio’s criminal history testimony was false, that the prosecution knew it was false, and that there was a reasonable likelihood the testimony affected the jury’s verdict. See Giglio v. United States, 405 U.S. 150 (1972). The district court denied relief, finding any Giglio error was harmless because Florida juvenile records are generally inadmissible.
The Eleventh Circuit affirmed for a different reason. It agreed the testimony was false and that the prosecution knew it was false, but disagreed with the district court’s conclusion that the juvenile records were inadmissible, explaining that juvenile records are admissible when the witness opens the door to prior convictions. When evaluating whether this false testimony prejudiced the jury, the Eleventh Circuit relied in part on a DNA test that was conducted years after the trial to deem the false testimony harmless, i.e., post-trial DNA testing that showed the presence of the victim’s blood on Whitton’s boots seized the day after the murder. After considering that post-trial DNA evidence (in addition to the trial evidence), the Eleventh Circuit affirmed the denial of habeas relief, holding that it was not “unreasonable for the State court to conclude” that even without any of Ozio’s testimony “there was ‘overwhelming evidence against Whitton.'”
The Supreme Court vacated the Eleventh Circuit’s judgment “because that court should not have considered the post-trial DNA evidence in assessing whether the Florida Supreme Court reasonably determined that Ozio’s testimony was immaterial to the jury’s verdict. Because the post-trial DNA evidence was not presented to the jury (indeed, did not exist at the time of the trial), that evidence could not have influenced the jury’s verdict. It therefore sheds no light on whether (or to what extent) Ozio’s testimony influenced that verdict.”
Justice Thomas dissented, joined by Justice Alito, except as to Part III-B.
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