United States v. Abel
United States v. Abel, 469 U.S. 45, 105 S.Ct. 465, 83 L.Ed.2d 450 (1984), discusses the admissibility of gang membership to show the bias of a witness.
In Abel, the government sought to prove the bias of a defense witness through cross-examination and extrinsic evidence showing that the defendant and the defense witness were members of the same prison gang, and that the tenets of the gang required members to "lie, cheat, steal, and kill" to protect each other. Id. at 48, 105 S.Ct. at 467.
The Court held that "a witness' and a party's common membership in an organization, even without proof that the witness or party has personally adopted its tenets, is certainly probative of bias." Id. at 52, 105 S.Ct. at 469.
The Court also rejected the argument that the district court should cut off the description of the type of gang because evidence of the gang's tenets was unfairly prejudicial.
The Court observed:
This argument ignores the fact that the type of organization in which a witness and a party share membership may be relevant to show bias.... The attributes of the Aryan Brotherhood--a secret prison sect sworn to perjury and self-protection--bore directly not only on the fact of bias but also on the source and strength of Mill's bias. Id. at 54, 105 S.Ct. at 470.
The Court noted that the defendant had not been unfairly prejudiced where the district court had prevented the use of the term "Aryan Brotherhood" and had given a cautionary instruction. See id. at 54-55, 105 S.Ct. at 470-71.
The Court thus held that the district court had not abused its discretion in permitting the testimony about gang membership.