Rule 609.1 Evidence of bias, interest, or motive

This rule has no federal counterpart, which means that common-law principles of bias, interest, or motive impeachment govern the practice in the federal courts. The problem is that the common law is divided on the question whether the impeaching material must, on cross-examination, be brought to the attention of the witness being impeached as a precondition to the proffer of extrinsic evidence. McCormick §40.

Rule 609.1 settles the issue and restates the rule of State v. Murphy, 59 H. 1, 17-18, 575 P.2d 448, 459-60 (1978):

The general rule is that a witness may be impeached through a showing of bias, hostility or prejudice, and this may be done by use of the witness' own testimony or by other evidence.... We believe that the correct rule is ... that before any bias of a witness can be introduced, a foundation must first be laid by cross-examining the witness regarding the facts which assertedly prove the bias. Two reasons [are] recognized ... for such a preliminary foundation. First, the foundational cross-examination gives the witness a fair opportunity to explain statements or equivocal facts which, standing alone, tend to show bias. Second, such cross-examination lends expediency to trials, for if the facts showing bias are admitted by the witness, the introduction of extrinsic evidence becomes unnecessary.