Although this issue most commonly comes up in connection with experts, it is not necessarily so limited. In case 1, witness A testifies. The trial judge finds that the witness lied or otherwise offered untrustworthy testimony (for an expert, motives may be challenged or testimony may be rejected on Daubert grounds), and the judge so writes in an order or opinion. Can that opinion be used to cross examine the witness in a subsequent case? There are decisions going both ways on this issue, the Second Circuit stating in the U.S.F.L. v. N.F.L. decision years ago: ‛Probing into the qualifications of an expert is a far cry from probing into differing judicial reactions to [the expert’s] prior testimony in totally unrelated cases.“ United States Football League v. National Football League, 842 F.2d 1335, 1375 (2d Cir. 1988). On February 23, 2007, District Judge Robin Cauthron answered this question in the negative, precluding the use of the prior judicial opinion to attack the credibility of both a hearsay declarant and a witness testifying live at trial, in Armstrong v. Bair, 2007 U.S. Dist. LEXIS 13375 (W.D. Okla. Feb. 23, 2007), but still allowing the cross-examiner to get some mileage out of the prior opinion.

First, Judge Cauthron held that the prior judicial opinion did not constitute ‛opinion“ evidence as to character within Fed.R.Evid. 405(a) because the first court did not have the requisite personal knowledge of the witness’s character.

Second, with respect to the hearsay declarant, Judge Cauthron adopted the view of the Third Circuit — contrary to the Second Circuit — that Rule 806 does not modify Rule 608(b)’s ban on the introduction of extrinsic evidence of instance of prior conduct that bear on a witness’s character for truthfulness. Compare United States v. Saada, 212 F.3d 210, 220-21 (3d Cir. 2000), with United States v. Friedman, 854 F.2d 535, 570 n. 8 (2d Cir. 1988).

Third, with respect to the live witness, she held that the prior opinion could be the basis of questioning under Rule 608(b) but was not itself admissible. She then quoted at length from a Seventh Circuit case giving substantial leeway in the questioning allowed with respect to the prior judicial opinion:

‛Rule 608(b) … would have allowed the judge to permit the defendants’ lawyer in this case to ask the witnesses whether they had lied in two previous suppression hearings. And there is nothing to suggest that the ‘inquiry’ could not have extended to asking the witness whether a judge, say, had ever found him not to be a credible witness…. There would have been a problem in this case had the defendants’ lawyer asked ‘has any federal judge ever found that you lied on the stand?’ and when the witness answered ‘no’ the lawyer sought to have the judge’s finding placed in evidence. That would be ‘extrinsic evidence’ and would be barred by Rule 608(b) if the evidence were being used to undermine the witness’s ‘character for truthfulness.’“ United States v. Dawson, 434 F.3d 956, 958-59 (7th Cir. 2006).

Is a prior judicial opinion ‛evidence“ within 608(b)? What if the opinion itself is not offered as an exhibit? Is it hearsay? Does it matter if the prior decision collaterally estops the witness? Why doesn’t the prior judge have sufficient personal knowledge of the witness to offer an ‛opinion?“ Many issues are raised by the use of a prior judicial opinion to cross-examine a witness, and the decisions are not uniform. Note that this is primarily a jury issue. Nothing prevents the use of a prior judicial opinion in briefing to the court, in a pretrial memorandum, on a Daubert motion in the case of experts, on a sanctions motion, or otherwise.