469 U.S. 45 (1984)
United States v. Abel is a foundational Supreme Court decision on impeachment for bias—an area of evidence law that remains vital in both criminal and civil trials.
May the prosecution introduce extrinsic evidence that a defense witness and the defendant share membership in a prison gang whose tenets include lying for fellow members, for the purpose of impeaching the witness for bias, notwithstanding Federal Rule of Evidence 608(b) and potential prejudice under Rule 403?
Bias is always relevant to a witness's credibility and may be proven by extrinsic evidence. Federal Rule of Evidence 608(b) limits extrinsic evidence of specific instances of conduct only when offered to attack or support a witness's character for truthfulness, not when offered to show bias, motive, or interest. Relevant bias evidence is admissible subject to the trial court's discretion under Rule 403, and, when necessary, the court may give a limiting instruction under Rule 105 to confine the evidence to its proper purpose. Evidence offered to show bias is not hearsay when not offered for the truth of the matter asserted but to demonstrate the existence of a relationship or motive affecting credibility.
Yes. The Supreme Court held that the prosecution could impeach the defense witness with extrinsic evidence of shared gang membership and the gang's oath requiring members to lie for each other, because it was offered to show bias rather than character. The trial court did not abuse its discretion under Rule 403.
Abel is a marquee case delineating the boundary between bias impeachment and character impeachment. It teaches that: (1) bias is always relevant and can be proven with extrinsic evidence; (2) Rule 608(b) does not bar such extrinsic proof because that rule targets character for truthfulness, not bias; (3) trial judges wield broad discretion under Rule 403 to balance probative value against unfair prejudice; and (4) limiting instructions under Rule 105 are a key tool to cabin permissible uses. For exams and practice, Abel is often paired with Davis v. Alaska to illustrate the primacy of bias evidence and the distinct analytical pathways under the Rules. It also serves as a caution that highly inflammatory evidence (e.g., gang affiliation) may still be admissible when its probative force on a witness's motive is strong and the court's safeguards are in place.