dissenting:
A prospective juror told the court that her ability to be a fair juror would be affected because a drug dealer had murdered her uncle. Despite this admission, she was nevertheless seated. Because the presence of a biased juror is structural error requiring reversal, I respectfully dissent.
A juror is “biased in fact” when the juror has “a state of mind that leads to an inference that the person will not act with entire impartiality.” United States v. Gonzalez, 214 F.3d 1109, 1112 (9th Cir. 2000) (quoting United States v. Torres, 128 F.3d 38, 43 (2d Cir.1997)). “Actual bias is typically found when a prospective juror states that he can not be impartial.” Fields v. Brown, 503 F.3d 755, 767 (9th Cir.2007) (en banc). Because an impartial jury is so fundamental to the Sixth Amendment right to a fair trial, “[d]oubts regarding bias must be resolved against the juror.” Gonzalez, 214 F.3d at 1114 (quoting Burton v. Johnson, 948 F.2d 1150, 1158 (10th Cir.1991)).
Here, the trial judge began by asking the juror whether she thought that her experience would affect her “in any way, in being a fair juror in this case?” After some equivocal colloquy, the trial judge asked for “pretty direct assurance” as to whether her experience “would cause [her] a problem.” After an ambiguous answer, the court pressed further, asking directly whether the juror thought it would cause her a problem. In response, the juror finally said that the murder of her uncle “did affect my family, so I think, yes it will *1155affect me.” The court then told the juror to return to her seat.
Our case law compels the conclusion that the juror was impermissibly biased. In Gonzalez, we held that a juror was impliedly and actually biased even though the juror never once stated that she could not be impartial. Gonzalez, 214 F.3d at 1114. The prospective juror there stated repeatedly that she would “try” to treat the defendant fairly. Id. at 1111. That was enough for us to conclude that the prospective juror was actually biased. We held that, “[wjhen a juror is unable to state that she will serve fairly and impartially despite being asked repeatedly for such assurances, we can have no confidence that the juror will ‘lay aside’ her biases or her prejudicial personal experiences and render a fair and impartial verdict.” Id. at 1114.
The juror’s answers here reflect more bias than the prospective juror in Gonzalez. In Gonzalez, the prospective juror was at least able to state conclusively that she would try to be impartial. Here, the juror’s final answer was that her ability to serve as a juror would be affected by her past experience. She could not ultimately state that she could “serve fairly and impartially.” Id.1
The facts of this case and Gonzalez stand in stark contrast to cases in which we have concluded that no actual or implied bias existed. For example, in Fields, the prospective juror responded that he would be unaffected by his prior experience and would base his decision “strictly on the charges and the evidence that’s presented.” 503 F.3d at 764. When the judge followed up with: “And you would accept and follow the law given to you by the court and apply it, to the best of your ability, to the facts as you determine them to be?,” the prospective juror responded: “Definitely.” Id. The prospective juror’s answers were clear and unambiguous, and the Fields court rightfully had no trouble dismissing the actual bias claim. Similarly, in United States v. Mitchell, 502 F.3d 931 (9th Cir.2007), the juror initially indicated she thought that certain types of crime should be punishable by death, but concluded by saying “she could keep an open mind.” Id. at 955. Fields and Mitchell follow the usual course of voir dire examination in which a juror expresses some reservations, but upon questioning resolves doubt and asserts that he or she can put preconceptions or prior experiences aside and impartially decide the case based on an open-minded and fair consideration of the applicable law and evidence. See also United States v. Nelson, 277 F.3d 164, 202-03 (2d Cir.2002) (“[I]t is important that a juror who has expressed doubts about his or her impartiality also unambiguously assure the district court, in the face *1156of these doubts, of her willingness to exert truly best efforts to decide the case without reference to the predispositions and based solely on the evidence presented at trial.”).
In contrast, the juror in our case affirmatively concluded that her past experience would affect her ability to be a fair juror. Her statement did not come at the beginning of voir dire; it came at the conclusion of her examination after the trial court had emphasized the need for a “direct assurance” of impartiality. “A court confronted with a colorable claim of juror bias must undertake an investigation of the relevant facts and circumstances.” Dyer v. Calderon, 151 F.3d 970, 974 (9th Cir.1998) (en banc). Moreover, “[a] court must excuse a prospective juror if actual bias is discovered during voir dire.” United States v. Allsup, 566 F.2d 68, 71 (9th Cir.1977). In the face of a statement that a juror’s past experience would affect her ability to be a fair juror, the district court should not have allowed her to sit on the jury.2
Juror bias is structural error requiring reversal. Dyer, 151 F.3d at 973 n. 2. We have long recognized that biased jurors so infect the criminal trial process that their presence on a jury requires automatic reversal of any verdict produced by that jury. United States v. Hendrix, 549 F.2d 1225, 1227 (9th Cir.1977). If even one juror is unduly biased or prejudiced or improperly influenced, the criminal defendant is denied his Sixth Amendment right to an impartial panel. Id.
As the majority rightly points out, defense counsel did not challenge the juror for cause or raise any other objection to her empanelment. However, because juror bias is a structural error, plain error analysis is not appropriate. United States v. Hamilton, 391 F.3d 1066, 1071 (9th Cir. 2004) (“ ‘We only review for plain error or assess whether an error is harmless when the error is not structural.’ ” (quoting United States v. Sanchez-Cervantes, 282 F.3d 664, 670 (9th Cir.2002))).
Additionally, although the majority correctly observes that “[t]he principal way” trial judges normally assure an impartial jury “is through the system of challenges exercised during voir dire,” Allsup, 566 F.2d at 71, our case law nowhere defines that system of challenges as the only way to achieve an impartial jury. See Dyer, 151 F.3d at 973 (describing voir dire only as “[o]ne important mechanism” for ensuring impartiality). Trial judges have a duty to excuse a prospective juror if bias is discovered during voir dire. Allsup, 566 F.2d at 71. Because seating a biased juror is a structural error, reversal is required.
For these reasons, I respectfully dissent.
. The majority attempts to distinguish Gonzalez by noting that in Gonzalez, the defendant's counsel asked to strike the prospective juror. Because Mitchell's counsel did not move to strike Jane Doe, the majority argues, Doe’s bias must have been particularly severe to constitute error. The majority thus creates two standards for juror bias depending on whether the bias was objected to below. This argument finds no support in case law and is irrelevant to a structural error analysis because it conflates the standard of review and bias analyses. The correct analysis is simpler: the presence of a biased juror is structural error requiring automatic reversal.
The majority additionally invokes the principle that a defendant may forfeit a constitutional right by failing to assert the right. That rule does not apply in cases of structural error. The Second Circuit has held that the right to an impartial factfinder was "inherently unwaivable” because to hold otherwise would result in "fundamentally unfair” proceedings against the defendant. United States v. Nelson, 277 F.3d 164, 205 (2d Cir.2002) (citing United States v. Fay, 300 F.2d 345, 350-51 (2d Cir.1962)).
. The majority cannot cite one case where a court found impartial a prospective juror who ultimately concluded, as Doe did, that she was affected by a crime similar to the one bring tried.