“Extrinsic evidence will not be admitted on a collateral matter.” This principle typically occurs in two contexts, admission of character evidence and contradicting specific testimony.

Character Evidence

When permitted, all the lawyer can do is ask the witness about the prior act. No other outside (extrinsic) evidence may be permitted to describe the act. In other words, all the lawyer can say is, “Were you convicted of such crime?” to which the witness gives the response. Regardless of the answer, the lawyer cannot supplement the information (even if the answer is a denial). However, there is a way around this rule, if the purpose is to prove another matter, then the evidence may be admissible.

Contradicting Specific Testimony

Extrinsic evidence may be admitted if the purpose is to contract specific testimony. For instance, witness answers “no” to a question. The questioner may then present outside evidence to show that the answer really ought to have been “yes.”

In Hall v. State, 109 P.3d 499 (Wyo. 2005), Hall was being charged with running a drug lab. One witness had already pleaded guilty to running the lab and was offered benefits for testimony against others in the crime. Hall now wants to present testimony that the witness has (1) a propensity to threaten turning people in for self-interest reasons, and (2) has falsely accused others of possession. The purpose of presenting this material is to show the witness was biased.


The content contained in this article may contain inaccuracies and is not intended to reflect the opinions, views, beliefs, or practices of any academic professor or publication. Instead, this content is a reflection on the author’s understanding of the law and legal practices.

Categories: 2L Spring, Evidence

Will Laursen

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