Edward J. Imwinkelried (University of California, Davis – School of Law) has posted 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 on SSRN.
Here is the abstract:
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.