Opinion by Judge WALLACE; Dissent by Judge THOMAS.
WALLACE, Senior Circuit Judge:
Mitchell appeals from his conviction and sentence for possession with intent to distribute cocaine base in violation of 21 U.S.C. § 841(a)(1) (Count One), and possession of marijuana in violation of 21 U.S.C. § 844 (Count Two). On Count One, he was sentenced to a mandatory term of life imprisonment without release and ten years of supervised release. On Count Two, he was sentenced to a term of 90 days of imprisonment and three years of supervised release. The sentences of imprisonment are to run concurrently, as are the terms of supervised release. Although Mitchell raises a number of issues on appeal, in this opinion we deal with only his claim that he was denied his constitutional right to an impartial jury. We address his other arguments in a companion unpublished disposition. The district court had jurisdiction pursuant to 18 U.S.C. § 3231. We have jurisdiction over this timely filed appeal pursuant to 28 U.S.C. § 1291 and 18 U.S.C. § 3742. We affirm.
I.
During voir dire of prospective jurors at Mitchell’s trial, the court engaged in the following sidebar colloquy with government attorney Fahami, defense counsel Edwards, and a prospective juror, whom we refer to here as Jane Doe:
THE COURT: [Jane Doe], please, after we recess, you indicated to the courtroom deputy that you had some sort of — there was somebody in your family *1149or some Mend had had some sort of contact with illegal drugs, is that right?
PROSPECTIVE JUROR [JANE DOE]: Yes. My — it happened about nine, ten years ago in Mexico. One of my uncles was actually killed by a drug dealer.
THE COURT: Okay. How old were you then?
PROSPECTIVE JUROR [JANE DOE]: I’m 26.
THE COURT: Do you remember any of the circumstances involving—
PROSPECTIVE JUROR [JANE DOE]: I was actually here in the United States, and it happened down in Mexico. But, it was my mom’s youngest brother.
THE COURT: All right. Do you think that what happened there would affect you, in any way, in being a fair juror in this case?
PROSPECTIVE JUROR [JANE DOE]: Um, I don’t think so.
THE COURT: Well, you’re going — is that the best you can do, or can you put that out of your mind?
PROSPECTIVE JUROR [JANE DOE]: Um, I think it would be on my mind, to tell you the truth' — -no, I’ll be fine. No. Actually, I’m fine.
THE COURT: I need pretty direct assurance on this, if you think that would cause you a problem.
PROSPECTIVE JUROR [JANE DOE]: I think it will, now that I think about it. I didn’t think about it before. But now that it’s in my mind, it’s a little different, I think.
THE COURT: You think it would cause you a problem?
THE COURT: You have to whisper now.
PROSPECTIVE JUROR [JANE DOE]: Sorry. It didn’t affect me—
THE COURT: You have to whisper.
PROSPECTIVE JUROR [JANE DOE]: It did affect my family, so I think, yes, it will affect me.
THE COURT: Okay. You may return to your seat.
(Side bar with the Court and counsel:)
THE COURT: Do counsel wish me to ask any additional questions of the juror? Ms. Fahami.
MS. FAHAMI: No, Your Honor.
THE COURT: Mr. Edwards.
MR. EDWARDS: No, Your Honor.
THE COURT: Do you wish — do counsel wish to challenge the juror?
MR. EDWARDS: No, Your Honor.
THE COURT: And on your side, Ms. Fahami?
MS. FAHAMI: No, Your Honor.
THE COURT: Neither counsel wishes to challenge for cause? Well, then we’ll be able to proceed then. Otherwise, I was going to have to take a step back.
With [sic] those questions and the answers affect your challenge or waiver of your first peremptory, Ms. Fahami?
MS. FAHAMI: No, Your Honor.
THE COURT: All right. Thank you.
Jane Doe was seated as a juror. Three days later, the jury convicted Mitchell of both counts on which he had been indicted. On appeal, Mitchell argues that he was denied his constitutional right to an impartial jury because Jane Doe harbored impermissible bias.
II.
Mitchell did not move to strike Jane Doe for cause during voir dire. Normally, where a defendant fails to raise a claim of error at trial, we will review that claim for plain error. Fed.R.Crim.P. 52(b) (“A plain error that affects substantial rights may be considered even though it was not *1150brought to the court’s attention”); United States v. Olano, 507 U.S. 725, 731, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993) (holding that Rule 52(b) “provides a court of appeals a limited power to correct errors that were forfeited because [they were] not timely raised in district court”).
Plain error exists where (1) there is an “error,” (2) that is “plain,” and (3) the error affects “substantial rights.” Id. at 732, 113 S.Ct. 1770. An “error” is any “[deviation from a legal rule,” and it is “plain” if it is “clear” or “obvious.” Id. at 732-34, 113 S.Ct. 1770. An error affects “substantial rights” if the defendant is prejudiced in such a manner as to “affect[ ] the outcome of the district court proceedings.” Id. at 734-35, 113 S.Ct. 1770. Even where these conditions exist, a court of appeals on plain error review should reverse a conviction only where the error “seriously affeet[s] the fairness, integrity or public reputation of judicial proceedings.” Id. at 736, 113 S.Ct. 1770 (internal quotation marks omitted).
Our law is ambiguous if not in conflict as to whether this standard of review applies to unpreserved claims of juror bias. In United States v. Olano, 62 F.3d 1180, 1192-93 (9th Cir.1995), we applied the plain error standard of review to a claim of juror bias where the defendant “did not move for mistrial” in the district court. Similarly, in United States v. Mitchell, we limited our review of a juror bias claim on appeal to plain error because the defendant “did not ask the[trial] court to excuse [the challenged juror] for cause.” 502 F.3d 931, 955 (9th Cir.2007), cert. denied, - U.S. -, 128 S.Ct. 2902, 171 L.Ed.2d 843 (2008), citing United States v. Mendoza-Reyes, 331 F.3d 1119, 1121 (9th Cir.2003) (per curiam), and United States v. Ross, 886 F.2d 264, 266 (9th Cir.1989).
However, in United States v. Sanchez-Cervantes, 282 F.3d 664, 670 (9th Cir. 2002), we held that “[w]e only review for plain error or assess whether an error is harmless when the error is not structural.” And in Dyer v. Calderon, 151 F.3d 970, 973 n. 2 (9th Cir.1998), this court en banc held that “the presence of a biased juror introduces a structural defect” into a criminal defendant’s trial. Cf. United States v. Hamilton, 391 F.3d 1066, 1071 (9th Cir. 2004) (holding that a violation of the Sixth Amendment right to counsel at “critical stage[s]” of criminal proceedings is not subject to plain error analysis); but see United States v. Brown, 26 F.3d 1124, 1126 (D.C.Cir.1994) (concluding that “plain error analysis is applicable to a sixth amendment claim not raised at trial”).
These latter cases, apparently in conflict with earlier decisions, suggest that plain error review may not be appropriate for unpreserved claims of juror bias. However, these cases may also be read as merely circumscribing the scope of plain error review with respect to such claims so that a defendant need not demonstrate that he was prejudiced by the presence of the challenged juror. Dyer, 151 F.3d at 973 n. 2 (“The presence of a biased juror cannot be harmless; the error requires a new trial without a showing of actual prejudice”). We need not resolve this ambiguity or conflict in our jurisprudence, however, because even if plain error review does not apply, we conclude that there was no error in the district court’s failure sua sponte to strike Jane Doe from the jury.
III.
The Sixth Amendment right to a jury trial guarantees the criminally accused a fair trial by a panel of impartial jurors. Id. at 973. Even if only one juror is unduly biased or prejudiced, the defendant is denied this constitutional guarantee. Id.; see also United States v. Plache, 913 F.2d 1375, 1377 (9th Cir.1990) (“It is well-settled that a single partial juror de*1151prives a defendant of his Sixth Amendment right to a trial by an impartial jury”).
In this case, Mitchell argues that he was denied his right to an impartial jury because the district court failed to strike Jane Doe as biased. To succeed on such a claim, a defendant usually bears the burden of demonstrating that the challenged juror was biased, and that the district court erred in failing to strike her from the jury. United States v. Martinez-Martinez, 369 F.3d 1076, 1081-82 (9th Cir. 2004), citing United States v. Hursh, 217 F.3d 761, 768 (9th Cir.2000). However, where as here, no motion was made during jury selection to dismiss the juror in question for cause, Mitchell assumes a greater burden: he must show that the evidence of partiality before the district court was so indicative of impermissible juror bias that the court was obliged to strike Jane Doe from the jury, even though neither counsel made the request. See, e.g., Ross, 886 F.2d at 266-67 (evaluating the sufficiency of the evidence before the district court in evaluating an unpreserved claim of juror bias); cf. Sims v. Rowland, 414 F.3d 1148, 1155-56 (9th Cir.2005) (holding that due process does not require a trial court to hold an evidentiary hearing sua sponte when presented with evidence of juror bias).
A.
“We have analyzed juror bias under two theories — actual bias and implied bias.” Estrada v. Scribner, 512 F.3d 1227, 1240 (9th Cir.), cert. denied, - U.S. -, 128 S.Ct. 2973, 171 L.Ed.2d 898 (2008). Actual bias is, in essence, “ ‘bias in fact’— the existence of 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 found where “a prospective juror states that he can not be impartial, or expresses a view adverse to one party’s position and responds equivocally as to whether he could be fair and impartial despite that view.” Fields v. Brown, 503 F.3d 755, 767 (9th Cir.2007) (en banc).
Implied bias is “bias conclusively presumed as a matter of law.” Gonzalez, 214 F.3d at 1111, quoting 47 Am.Jur.2d Jury § 266 (1995). The inquiry here is “whether an average person in the position of the juror in controversy would be prejudiced.” Id. at 1112, quoting United States v. Cerrato-Reyes, 176 F.3d 1253, 1260-61 (10th Cir.1999) (emphases and internal quotation marks omitted). Thus, we have presumed a challenged juror’s bias “where the relationship between a prospective juror and some aspect of the litigation is such that it is highly unlikely that the average person could remain impartial in his deliberations under the circumstances.” Tinsley v. Borg, 895 F.2d 520, 527 (9th Cir.1990), quoting Person v. Miller, 854 F.2d 656, 664 (4th Cir.1988). We have cautioned, however, that bias should be presumed only in “extreme” or “extraordinary” cases. Tinsley, 895 F.2d at 527, quoting Smith v. Phillips, 455 U.S. 209, 222, 223 n. *, 102 S.Ct. 940, 71 L.Ed.2d 78 (1982) (O’Connor, J., concurring); see also Fields, 503 F.3d at 770 (holding that bias should be presumed only in “extreme situations”).
In Gonzalez, we applied these standards to conclude that a juror serving in a narcotics trial displayed impermissible bias where:
[the juror] disclosed the fact that her ex-husband, the father of her daughter, dealt and used cocaine — the same drug and conduct at issue here. Moreover, she described her former husband’s drug dealing as one of the reasons for her relatively recent divorce and the break-up of her family. She admitted *1152that the experience was painful. Asked three times whether she could put that experience aside and serve fairly and impartially, she never affirmatively stated that she could. Instead, she equivocated each time.
214 F.3d at 1113. We held that the juror’s equivocal statements regarding her ability to be impartial, coupled with “the similarity between her traumatic familial experience and the defendant’s alleged conduct,” warranted reversal of the defendant’s conviction “under either an express or implied bias theory.” Id. at 1114; see also United States v. Eubanks, 591 F.2d 513, 517 (9th Cir.1979) (per curiam) (presuming bias in a heroin conspiracy case on the part of a juror whose children were in prison for heroin-related crimes); United States v. Allsup, 566 F.2d 68, 71-72 (9th Cir.1977) (holding that bias may be presumed from the “potential for substantial emotional involvement” inherent where prospective jurors worked for a bank, which had a branch that defendants were charged with robbing).
By contrast, in Fields, this court sitting en banc concluded that the challenged juror did not harbor either actual or implied bias, despite the fact that his wife was a victim of a traumatic assault similar to the one involved at trial. 503 F.3d at 764-65. During voir dire, the juror volunteered that his “wife was assaulted and beaten, robbed, two years ago Christmas.” Id. at 764. When asked if he would be able to be fair and impartial, the juror answered in the affirmative. Id. He was subsequently empaneled on the jury with no objections from either party. Id. On collateral review and following an evidentiary hearing at this court’s request, we affirmed the district court’s finding that the juror had “truthfully represented that he was impartial” during voir dire. Id. at 767. Therefore, “there was no manifest error in the district court’s finding that [the juror] was not actually biased.” Id.
Fields also declined to presume bias on the part of the challenged juror, holding that “[b]eing the spouse of a rape victim is not, in and of itself, such an ‘extreme’ or ‘extraordinary’ situation that it should automatically disqualify one from serving on a jury in a case that involves rape.” Id. at 774. In so ruling, we emphasized that “prudence dictates that courts [determining whether to presume bias] should hesitate before formulating categories of relationships which bar jurors from serving in certain types of trials.” Id. at 772, quoting Tinsley, 895 F.2d at 527; see also Tinsley, 895 F.2d at 529 (holding that a presumption of juror bias was unwarranted where the defendant was on trial for rape, and the challenged juror had worked as a psychiatric social worker trained to deal with rape victims and at one point had testified on behalf of a rape victim).
B.
In this case, we conclude that the evidence of juror bias was insufficient to require the district court to strike Jane Doe from the jury sua sponte. When asked, “[d]o you think that what happened [to your uncle] would affect you, in any way, in being a fair juror in this case?” Jane Doe responded that she did not think so. After being pressed further by the district court, she answered, “no, I’ll be fine. No. Actually, I’m fine.” Critically, none of the subsequent questions explicitly returned to the theme of whether she could be a fair juror in this case. Rather, she was asked whether she could “put that [event] out of [her] mind,” and whether “[the event] would cause you a problem.” To these inquiries, Jane Doe answered that the experience “did affect my family, so I think, yes, it will affect me.”
Jane Doe’s answers were too vague and ambiguous to have obliged the district court to strike her sua sponte for actual *1153bias. In response to the only question directly inquiring into her ability to be an impartial juror, Jane Doe explicitly stated that her uncle’s death at the hands of a drug dealer would not affect her impartiality. Although she later stated that her uncle’s death would “affect” her, she did not elaborate on precisely how she would be affected, nor did the parties ask for further clarification. Clearly, once her uncle’s death was raised, it would be difficult for her to erase the event from her mind; but she never stated that it would prevent her from being impartial. Thus, unlike the juror in Gonzalez who testified that her husband’s drug dealing was a primary reason for their eventual divorce, Jane Doe did not indicate that her uncle’s death affected her in such a way as to impair her ability to be impartial. The district court therefore did not err in failing sua sponte to strike Jane Doe for actual bias. Cf. United States v. Alexander, 48 F.3d 1477, 1484 (9th Cir.1995) (denying actual bias claim where a juror affirmatively stated that she could remain impartial, despite the fact that her statements were somewhat equivocal).
In addition, the circumstances do not warrant a presumption of bias. Mitchell was on trial for possession of marijuana and possession with intent to distribute cocaine base. Jane Doe testified that her uncle was killed by a drug dealer in Mexico some ten years prior to trial. Although drug trafficking features in both Jane Doe’s personal experience and Mitchell’s conduct, we rejected an even closer personal connection as grounds for implied bias in Fields. In that case, the challenged juror’s wife had been a victim of an assault that was extremely similar to the conduct on trial. Yet we concluded that “[i]t cannot be said that the average person in [the challenged juror’s] position would be highly unlikely to remain impartial.” 503 F.3d at 774.
Similarly here, Jane Doe’s testimony reveals that her uncle’s killing at the hands of a drug dealer occurred a full decade before the trial, and in another country while she was in the United States. Moreover, Jane Doe had no personal recollection of the circumstances of her uncle’s killing except in the most general of terms. It is also salient that Mitchell was not accused of any violent conduct, making it even less likely that Jane Doe would connect him to her uncle’s killer. Thus, this is not a case like Gonzalez, Eubanks, or Allsup, where the challenged juror’s personal experience closely mirrored the conduct that was on trial, or where the juror’s personal situation made the juror especially vulnerable to bias because the case featured the same kind of conduct to which the juror was exposed. The district court therefore did not err; the district judge was not required to remove Jane Doe as a prospective juror sua sponte on the theory of implied bias.
C.
The dissent reads our precedents differently, concluding that Gonzalez compels reversal of Mitchell’s conviction. However, as described above, critical distinctions lie between Gonzalez and this case. Chief among those distinctions is the fact that the defendant in Gonzalez raised his claim of juror bias during voir dire, whereas Mitchell did not do so here. In fact, none of the cases the dissent cites in support of its position involves situations where, as here, the defendant failed to raise objections to the challenged juror at trial. This distinction is crucial. We have emphasized that, “[i]n most situations, voir dire, ‘the method we have relied on since the beginning,’ should suffice to identify juror bias.” Tinsley, 895 F.2d at 528, quoting Patton v. Yount, 467 U.S. 1025, 1038, 104 S.Ct. 2885, 81 L.Ed.2d 847 (1984); see also Fields, 503 F.3d at 774 *1154(“It is the role of voir dire to ferret out [relationships evidencing juror bias], and to develop the extent to which the juror’s ability to be impartial in the particular case is actually, or presumptively, affected”). Thus, “[c]hallenges for cause are the means by which partial or biased jurors should be eliminated.” Gonzalez, 214 F.3d at 1111; cf. Yakus v. United States, 321 U.S. 414, 444, 64 S.Ct. 660, 88 L.Ed. 834 (1944) (“No procedural principle is more familiar to this Court than that a constitutional right may be forfeited in criminal as well as civil cases by the failure to make timely assertion of the right before a tribunal having jurisdiction to determine it”).
Here, the court properly inquired into Jane Doe’s ability to be impartial and the parties were given an opportunity to follow up on that line of questioning, but were apparently satisfied with what they heard. Moreover, there is no allegation that Jane Doe was dishonest in her responses to the court’s questioning, or that she otherwise concealed material information about her past. Cf. Fields, 503 F.3d at 773 (“[W]e have never [presumed bias] when the juror was honest on voir dire”). Certainly, it must be significant that neither party at the time moved to strike Jane Doe for cause, neither attempted to elicit additional information about her uncle’s killing to set up a challenge, and neither exercised a peremptory challenge to exclude her. Under these circumstances, where the evidence of juror bias is weak, and neither party challenged the juror for cause, it is not error for the district court to allow the juror to serve at trial.
IV.
Because we conclude that Jane Doe’s voir dire statements were insufficient to evidence impermissible bias, we hold that the district court did not err in failing to strike her from the jury sua sponte. There was therefore no violation of Mitchell’s Sixth Amendment right to an impartial jury. For these reasons, and for those stated in the companion unpublished disposition, we uphold Mitchell’s conviction and sentence.
AFFIRMED.