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Discussion of the Use of Extrinsic Evidence to Impeach a Confidential Informant in a Federal Criminal Case

In federal criminal cases, defense attorneys may use extrinsic evidence to show a witness’ bias, but you may not use is to impeach by showing a specific instance of conduct.

FRE 608(b) states: Evidence of Character and Conduct of Witness

(b) Specific instances of conduct. Specific instances of the conduct of a witness, for the purpose of attacking or supporting the witness’ credibility, other than conviction of crime as provided in rule 609, may not be proved by extrinsic evidence. They may, however, in the discretion of the court, if probative of truthfulness or untruthfulness, be inquired into on cross- examination of the witness (1) concerning the witness’ character for truthfulness or untruthfulness, or (2) concerning the character for truthfulness or untruthfulness of another witness as to which character the witness being cross-examined has testified.

The giving of testimony, whether by an accused or by any other witness, does not operate as a waiver of the accused’s or the witness’ privilege against self-incrimination when examined with respect to matters which relate only to credibility.

This rule is well settled by the Courts, as they do not want to risk confusing the jury with a “mini trial” on issues that do not tend to prove or disprove the guilt of the defendant. See U.S. v. Martz, 964 F.2d 787 (8th Cir. 1992) but really I could refer you to any case dealing with this issue because there seems to be no exceptions.

A risk of proceeding under 608(b) is that if the Court does not allow you to introduce extrinsic evidence to impeach a witness, you will be bound by the witness’s answer. See U.S. v. Martz, 964 F.2d 787, 789 (8th Cir. 1992). Therefore the attorney must make a tactical decision, because once the question is asked, you are stuck with the response.

It has been pretty well laid out in case law that extrinsic evidence can be used to show bias even though the FRE’s do not specifically deal with the term “bias.” See U.S. v. Abel, 469 U.S. 45, 49 (1984). FRE 608 does not apply to evidence of bias or interest. Johnson v. Brewer, 521 F.2d 556, 562 (8th Cir. 1975). However it is in the judge’s discretion as whether to admit the evidence. U.S. v. Gomes, 177 F.3d 76, 81 (1st Cir. 1999). The judge may exclude the evidence it it would distract from the main issues and would add little practical value to the defense. Id. Inherent in this rule allowing is the rule that the cross-examiner is not bound by the witness’ answer when attempting to show the witness’ bias. See Johnson at 562.

The 5th Circuit went on further to explain the reasoning behind this concept. It explained that a witness’ bias, as opposed to veracity, is not a collateral issue and thus evidence of past behavior that proves or disproves bias is admissible. U.S. v. Fusco, 748 F.2d 996, 998 (5th Cir. 1984).

U.S. v. Phillips, 888 F.2d 38 (6th Cir. 1989) deals with both these issues. Here the defendant wanted to introduce testimony of the informant’s drug use at a certain party that the informant’s had denied. The Court did not allow in the testimony under 608(b) because it was too far removed from the case to have a bearing on the defendant’s guilt or innocents. However in this case the Court states, “Though the Federal Rules of Evidence do not specifically so state, prior misconduct of a witness which is probative of the bias of that witness may be proved by extrinsic evidence.” Id. at 41.

For further information, please contact the federal criminal defense attorneys at Silverman, Thompson, Slutkin & White.

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