Formalism versus Pragmatism in Evidence: Reconsidering the Absolute Ban on the Use of Extrinsic Evidence to Prove Impeaching, Untruthful Acts that Have Not Resulted in a Conviction

40 Pages Posted: 14 Oct 2014

See all articles by Edward J. Imwinkelried

Edward J. Imwinkelried

University of California, Davis - School of Law

Date Written: September 14, 2014


In the adversary system, a litigant not only has the right to present evidence supporting his or her theory of the case; the litigant is also entitled to attack the opposing testimony. In Crane v. Kentucky, 476 U.S. 683 (1986), the Supreme Court held that under the Sixth Amendment, the accused has a constitutional right to attack the weight and credibility of opposing testimony.

There are two ways in which the litigant can mount such an attack. First, the litigant may cross-examine the opposing witness. Second, the litigant can present “extrinsic evidence” of the impeaching facts: After the witness to be impeached has left the stand, the litigant may present documentary or testimonial evidence to prove the impeaching fact. Of course, if the witness to be impeached fully concedes the impeaching fact on cross-examination, there is no need for the litigant to resort to extrinsic evidence.

However, problems arise when, during cross-examination, the witness denies the impeaching fact. As a generalization, when the witness does so, the litigant may introduce extrinsic evidence to establish the impeaching fact. Thus, if the witness denies that she is biased against the cross-examiner’s client, the litigant may call another witness to prove the witness’s conduct evidencing the bias. Similarly, if the witness refuses to concede that he has suffered a felony conviction, the litigant may later introduce a certified copy of the conviction. Likewise, the litigant may sometimes employ extrinsic evidence when the litigant relies on prior inconsistent statement or specific contradiction impeachment.

There is, though, one notable exception to this generalization. Restyled Federal Rule of Evidence 608(b) permits the litigant to cross-examine a witness about a witness’s prior untruthful acts that have not resulted in a conviction. However, the text of Rule 608(b) prohibits the litigant from introducing “extrinsic prove specific instances of a witness’s conduct in order to attack...the witness’s character for truthfulness.” In its 2014 decision in Nevada v. Jackson, 133 S.Ct. 1990, 186 L.Ed.2d 62 (2014) the Supreme Court not only noted that prohibition; in dictum, the Court added that “[t]he constitutional propriety of this rule cannot be seriously disputed.” Id. at 1993, 186 L.Ed.2d 67.

Although the Supreme Court evidently does not have substantial doubts about the constitutionality of the prohibition, many lower courts entertain serious misgivings about the wisdom of the prohibition. Three lines of authority have emerged. In some jurisdictions, the litigant may at least confront the witness with documentary proof of an untruthful act when the witness himself or herself would be competent to authenticate the document. In other jurisdictions, the litigant may introduce extrinsic evidence when the evidence takes the form of a formal judicial finding that on a prior occasion the witness gave untruthful testimony. In still other jurisdictions, in sexual assault cases the accused may cross-examine the complainant about prior false rape accusations; and if the complainant denies the falsity of the prior complaints, the accused may introduce extrinsic evidence.

The thesis of this article is that the lower courts’ misgivings about the wisdom of Rule 608(b)’s absolute ban on extrinsic evidence are sound. It is true that formally, proof of another untruthful act by the witness is “collateral” in the sense that it relates only to the witness’s credibility. However, as a practical matter in a given case a showing of such an act may have far more probative value for impeachment than proof of a prior inconsistent statement or specific contradiction. Moreover, the ban can serve as a virtual invitation to perjury. Many witnesses will realize that a subsequent perjury prosecution is only a remote possibility. Worse still, a sophisticated witness may appreciate that there is no civil liability for perjurious testimony.

After critiquing the absolute ban codified in Rule 608(b), the article proposes an amendment to the rule. The article notes that the three lines of authority diverging from the ban all rely on considerations cognizable under Federal Rule 403's balancing test: minimal expenditure of court time, strong proof of the witness’s commission of the untruthful act, or an acute need for the evidence. The article suggests abolishing Rule 608(b)’s rigid ban and replacing it with a provision modeled after the balancing provisions set out in Rules 403, 412, and 609.

The thrust of this article is that it is unjustifiable to single out Rule 608(b) impeachment for a categorical ban on extrinsic evidence. The stated justification is flawed, and as a practical matter the ban can encourage perjury. If the witness’s earlier untruthful act did not result in a conviction, the witness might be emboldened because he “got away with it” once; and a sophisticated witness may reason that as a practical matter there is little risk in lying again. Rule 608(b) ought to be amended to create a disincentive for perjury.

Suggested Citation

Imwinkelried, Edward J., Formalism versus Pragmatism in Evidence: Reconsidering the Absolute Ban on the Use of Extrinsic Evidence to Prove Impeaching, Untruthful Acts that Have Not Resulted in a Conviction (September 14, 2014). UC Davis Legal Studies Research Paper No. 396, Available at SSRN: or

Edward J. Imwinkelried (Contact Author)

University of California, Davis - School of Law ( email )

Martin Luther King, Jr. Hall
Davis, CA CA 95616-5201
United States

Here is the Coronavirus
related research on SSRN

Paper statistics

Abstract Views
PlumX Metrics