In what circumstances can a witness be attacked in cross-examination?

In particular, a witness's credibility may be attacked by means of cross-examination directed toward revealing possible biases, prejudices, or ulterior motives of the witness as they may relate directly to issues or personalities in the case at hand . Id . (emphases added); see , e.g. , United States v. Abel , 469 U.S. 45, 52, 105 S.Ct. 465, 83 L.Ed.2d 450 (1984) ([b]ias is a term used ... to describe the

[829 F.3d 248]

relationship between a party and a witness which might lead the witness to slant, unconsciously or otherwise , his testimony in favor of or against a party (emphasis added)). Cross-examination is especially important where the evidence consists of the testimony of individuals whose memory might be faulty or who, in fact, might be perjurers or persons motivated by malice, vindictiveness , intolerance, prejudice, or jealousy. Greene v. McElroy , 360 U.S. 474, 496, 79 S.Ct. 1400, 3 L.Ed.2d 1377 (1959) (emphases added). A successful showing of bias on the part of a witness would have a tendency to make the facts to which he testified less probable in the eyes of the jury than it would be without such testimony. Abel , 469 U.S. at 51, 105 S.Ct. 465.