On July 11th, 2019, the Michigan Supreme Court released its unanimous opinion in People v Thorpe and People v Harbison, ___ Mich ___ (2019)(Docket No. 156777 & 157404) holding that expert witnesses are not permitted for vouch for the truthfulness of a complainant's account of sexual assault as this interferes with the role of the jury. This was a consolidated appeal for both cases.
In People v Thorpe, the Defendant was charged with three counts of second-degree criminal sexual assault against a young child. At his trial, the prosecutor called an expert witness to testify in the field of child sexual abuse and disclosure. The witness never physically examined the child complaint nor was provided specific information about the case. During direct examination, the expert witness was asked that, "of all of the times that you've handled child sexual abuse cases, what, in your experience, if you can say, is the percentage of children who actually do lie?" Despite defense counsel's objection, the judge permitted the expert witness to answer. He testified that children will lie in about "two to four percent of the cases" about sexual abuse and that "lying to bring that on to them is a relatively rare occurrence." The jury found Thorpe guilty as charged and the Court of Appeals upheld his conviction.
In People v Harbison, the Defendant was charged with several criminal sexual offenses (including CSC - First Degree) allegedly perpetrated against his niece. At his trial, the prosecutor called an expert witness in the field of child sexual abuse diagnostics. The witness physically examined the child and did not find any signs of sexual abuse that would substantiate the child's allegations, but she nevertheless indicated that the child had "probable pediatric sexual abuse" after citing statistics from a scholarly journal. The jury found Harbison guilty as charged. On appeal, the case had a lengthy procedural history but ultimately comes to the Michigan Supreme Court to determine whether the expert witness's testimony was plain error requiring reversal of the convictions.
Although the cases are consolidated, the standards of proof to justify reversal in each case is different. In Thorpe, defense counsel objected to the expert witness's testimony, preserving the issue for appeal. Since the issue was preserved, Thorpe has the burden of showing that the conviction should be set aside if, after examination of the case, the appellate court determines that is "more probable than not" that error resulted in a miscarriage of justice. In Harbison, defense counsel did not object to the expert witness's testimony so the issue was not preserved. As a result, he is held to the much higher and more difficult plain-error standard (e.g. appellate court may reverse a conviction on the basis that a clear and obvious error occurred that affected substantial rights).
In Thorpe's case, the Michigan Supreme Court found that it is more probable than not that a different outcome would have resulted without the expert witness's testimony that children lie about sexual abuse 2% to 4% of the time. The expert improperly vouched for the credibility of the child victim by saying that there is a slim chance that the child was lying and there would only be two specific scenarios where a child would lie (neither scenario applicable to this case). This results in the expert witness effectively testifying that there was zero percent chance that the child was lying. Since the trial was essentially a contest of credibility between the defendant and the child (no physical evidence, no inculpatory admissions and no other witnesses), then the improperly admitted expert testimony likely affect the jury's ultimate decision. Therefore, his convictions were reversed.
In Harbison's case, the Michigan Supreme Court found that a plain error was established that affected his substantial rights. It is improper for an expert witness to testify that, although he or she found no physical evidence, he or she would still offer the opinion that the child was sexually assaulted. The expert witness's assessment was wholly based on the child's emotional state ("agitated, extremely nervous and shaking") but not based on any findings in the witness's field of expertise as an obstetrician or gynecologist. This testimony is impermissible because the conclusion is only based on the expert's opinion that the child told the truth. The error was plain and obvious because the expert witness made a clear statement vouching for the truthfulness of the child against established case law. The error also affects substantial rights because allowing the expert witness's vouching statement very likely bolstered the child's uncorroborated testimony. Like Thorpe, Harbison's trial was a credibility contest between the defendant and the child so the expert witness's opinion certainly affected the jury's verdict and affected the integrity of the trial. Therefore, his convictions were reversed.
These decisions recognize that jurors, who are lay people, can be heavily swayed and influenced by expert witnesses in shaping their verdict. They assume that these experts have the experience, the knowledge and the scientific analysis to guide them towards the correct result in the case. These assumptions can be very dangerous when the expert is merely offering an opinion not based on any training or analysis relevant to their field. The assumption can be downright fatal to the Defendant's case when the expert offers an opinion about the trustworthiness of a witness based on a hunch or suspicion. A jury of twelve will look more like a jury of one when every one of them has been improperly swayed by the expert. Only the jury (or a judge in a bench trial) is qualified to evaluate the testimony of each witness and decide who to believe and who is lying. Anything that improperly affects that determination is an affront to a fair trial.