Can a witness be vouched for?

Vouching consists of placing the prestige of the government behind a witness through personal assurances of the witness's veracity, or suggesting that information not presented to the jury supports the witness's testimony. United States v. Necoechea, 986 F.2d 1273, 1276 (9th Cir. 1993). Vouching for the credibility of a witness or expressing a personal opinion concerning the accused's guilt can pose two dangers. First, it can convey the impression that evidence known by the prosecutor but not presented to the jury supports the charges, and thus it

Page 34

can jeopardize the defendant's right to be tried solely on the basis of the evidence presented to the jury. United States v. Young, 470 U.S. 1, 18 (1985). Second, the prosecutor's opinion reflects the imprimatur of the government and may induce the jury to trust the government's judgment rather than its own assessment of the evidence. Id. at 18-19.