In United States v. Collar, --- F.4th ---, No. 23-2939 (9th Cir. 2026), the Court vacated Attila Colar’s conviction on 44 counts arising from an alleged scheme to defraud the Paycheck Protection Program and efforts to obstruct the investigation, reversed the district court’s judgment, and remanded for a new trial based on the district court's failure to adequately address a juror bias.
The Sixth Amendment guarantees criminal defendants the right to trial by an impartial jury. The participation of even a single biased juror in rendering a guilty verdict is structural error requiring reversal. To safeguard this right, a district court must address any signs of bias during jury selection and throughout trial. The court has broad discretion over how to investigate a juror’s impartiality. That discretion, however, governs the form of the inquiry, not whether to conduct one. Once a colorable issue of juror bias arises, the court must investigate before the juror continues to serve, and the inquiry must match the seriousness of the claim. The court cannot defer that obligation simply because the juror is an alternate.A jury convicted Attila Colar on 44 federal counts arising from an alleged scheme to defraud the Paycheck Protection Program and efforts to obstruct the investigation. At voir dire, Colar advanced a defense theory that he maintained throughout his trial: law enforcement targeted him based on his race and religion. After the jury was impaneled, an alternate juror expressed actual bias against Colar. He told the court that he had a strong negative reaction to Colar’s defense and that he had concluded that the defense lacked substance and credibility.
The district court abused its discretion by deferring any meaningful investigation into the juror’s bias until he was needed on the regular panel. And its belated inquiry did not confirm that the juror could set aside the bias he previously expressed or that continued exposure to the defense theory would not revive it. The juror’s resulting participation in the verdict was structural error. We reverse and remand for a new trial.A district court’s duty to protect against juror bias begins, but does not end, at voir dire. Voir dire allows the parties and the court to identify and investigate prejudice at the outset. Rosales-Lopez v. United States, 451 U.S. 182, 188 (1981). But the court’s obligation does not end when the jury is impaneled; trial courts must remain “ever watchful to prevent prejudicial occurrences and to determine the effect of such occurrences when they happen.” Smith v. Phillips, 455 U.S. 209, 217 (1982). When information casting doubt on a sitting juror’s impartiality comes to the court’s attention during trial, its continuing obligation to ensure an impartial jury can be described in two steps.First the court must assess whether the information before it amounts to a “colorable claim of juror bias.” Dyer, 151 F.3d at 974. A colorable claim is not “wholly insubstantial and frivolous.” See Keniston v. Roberts, 717 F.2d 1295, 1298 (9th Cir. 1983). If the information does not rise to a colorable claim, the inquiry ends. But a court presented with a colorable claim of juror bias must take a second step and inquire further. It “must undertake an investigation of the relevant facts and circumstances” and “erect[], and employ[], a suitable framework for investigating the allegation of bias and gauging its effects.”The court has considerable discretion in how it investigates juror bias. It may attempt a rehabilitative colloquy,see United States v. Alexander, 48 F.3d 1477, 1484 (9th Cir. 1995), hold an evidentiary hearing, see Hendrix, 549 F.2d at 1227–29, or excuse the juror outright, see Gonzalez, 214 F.3d at 1114. Still, this discretion is “not unbounded.” United States v. Eubanks, 591 F.2d 513, 516 n.3 (9th Cir. 1979). Which framework fits depends on “the content of the allegations, including the seriousness of the alleged misconduct or bias, and the credibility of the source.” Hendrix, 549 F.2d at 1227–28; Dyer, 151 F.3d at 975 (noting that an in camera hearing to investigate potential bias must “be reasonably calculated to resolve the doubts” about a juror’s impartiality). The more serious the claim, the more in-depth the inquiry must be. See Hendrix, 549 F.2d at 1229. In conducting this inquiry, the court “must find facts, not make assumptions,” Dyer, 151 F.3d at 976, resolving any doubts about the juror’s impartiality against the juror, Gonzalez, 214 F.3d at 1114. And the court should promptly investigate such claims, rather than “leaving the matter in doubt” and the juror in place. See Dyer, 151 F.3d at 976.Applying this framework, we hold that the district court abused its discretion. We appreciate the difficulty of addressing a pro se defendant’s challenge to a vocal alternate juror. But Juror 48’s statements raised a colorable issue of whether he was biased. That demanded a searching inquiry before he continued to serve on the jury as an alternate. Instead, the court deferred an investigation until Juror 48 was needed for the regular jury panel. This was legal error. See Hinkson, 585 F.3d at 1261–62. And the court’s belated investigation, after Juror 48 had heard evidence, failed to establish that he set aside the bias he previously expressed or that continued exposure to the defense theory would not revive it. Its finding that Juror 48 was not actually biased thus lacked sufficient support in the record. Id. at 1262.
