Kelly on Malpractice

Suppose your opponent’s expert testifies that, in his opinion, your client’s version of the facts is not credible or that, in his opinion, the defendant physician’s account is more trustworthy. This happens more often than not. It can be subtle or blunt. You need to stop this improper attacking or bolstering of credibility with a motion in limine before it damages your case. Experts may not offer opinions based on their personal assessment of the credibility of another witness’s testimony. Credibility of witnesses is exclusively within the province of the jury. United States v. Richter, 826 F.2d 206, 208 (2d Cir.1987). Experts may never assess the credibility of other witnesses at trial. Even medical experts like psychiatrists or psychologists, with knowledge and skills that relate directly to credibility, may not state an opinion whether another witness is credible. United States v. Azure, 801 F.2d 336, 340-41 (8th Cir.1986). Just because the expert is a psychiatrist does not give him license to be a lie detector in the courtroom. That is the jury’s function. It is reversible error to permit an expert to bolster testimony with credibility assessments and thereby “usurp the jury’s fact-finding function.” United States v. Antone, 981 F.2d 1059, 1062 (9th Cir.1992). The expert would usurp the jury’s fact-finding function if allowed to comment on a witnesses’ credibility.

When an expert comments on the credibility of a witness, it should be excluded as “overly prejudicial.” U.S. v. Scop, 846 F.2d 135, 142 (2nd Cir.1988). For example, expert A may not offer an opinion as to relevant facts based on A’s assessment of the trustworthiness or accuracy of witness B, where B’s credibility is an issue for the jury. This is known as the Scop rule, which is followed by the federal courts. See Lindsey v. United States, 237 F.2d 893, 895-97 (9th Cir.1956) (finding reversible error where a psychiatrist testified to witness’s credibility); United States v. Binder, 769 F.2d 595, 602 (9th Cir.1985) (finding expert testimony that buttressed credibility of another witness was improper); United States v. Awkard, 597 F.2d 667, 671 (9th Cir.1979) (declaring that “Credibility…is for the jury…. The jury is the lie detector in the courtroom”). The expert is not the lie detector. He is not on the jury. The Scop rule is followed by a legion of state courts. See People v. Wells, 12 Cal.Rptr.3d 762 (Cal.Ct.App.2004) (“Jurors are generally considered to be equipped to judge witness credibility without the need for expert testimony”) (citing People v. Smith, 68 P.3d 302 (Cal.2003)); People v. Guilbeaux, 761 P.2d 255 (Colo.App.1988) (expert testimony as to victim’s credibility substantially influenced jury and affected fairness of the trial); State v. Oliver, 372 S.E.2d 256 (Ga.Ct.App.1988) (question regarding victim’s credibility warranted mistrial); Davis v. State, 527 So.2d 962 (Fla.Ct.App.1988) (statement that victim “was frank” with psychologist warrants reversal); Fuller v. State, 540 So.2d 182 (Fla.Ct.App.1989) (expert testimony vouching for truthfulness of witness is plain error); Goodson v. State, 566 So.2d 1142 (Miss.1990) (physician’s opinion of truthfulness of child is error requiring reversal); State v. Holloway, 347 S.E.2d 72 (N.C.Ct.App.1986) (plain error to admit pediatrician’s testimony on credibility where state’s entire case depended upon victim’s testimony); State v. Nelson, 777 P.2d 479 (Utah 1989) (where determination of guilt is based on jury’s assessment of credibility of victim and defendant, expert testimony bolstering child’s credibility was “harmful”).

In Tennessee, the prohibition against an expert buttressing the credibility of another witness is called the Schimpf rule. This is Tennessee’s analog to the Scop rule. In State v. Schimpf, 782 S.W.2d 186 (Tenn.Crim.App.1989), a psychologist, who claimed expertise in the evaluation and treatment of sexually abused children, rendered an opinion about whether the victim had been abused. The expert’s opinion was used to buttress the victim’s credibility. The appellate court held that the expert’s attempt to buttress the victim’s credibility was improper. Id. at 195. Like Scop, the Schimpf court went on to say that the probative value of the expert testimony was “substantially outweighed by the danger that it unfairly prejudiced, confused, or misled the jury.”

An expert cannot bolster or attack the credibility of one witness at the expense of another. Make sure you stop it in limine.