State v. Olsen

An expert witness' testimony, erroneously admitted, will not be deemed a harmless error when that testimony is used to bolster the complainant's credibility and the case hinges on that credibility determination.

Defendant was charged with subjecting the complainant to sexual contact. At trial, the state offered evidence from the complainant’s mother and a recording from defendant. The complainant testified that defendant made her touch him sexually, but this conflicted with her prior sworn testimony. There was no forensic evidence to corroborate the alleged abuse. The state’s expert witness diagnosed the complainant with sexual abuse by the defendant, predicated upon what the mother and complainant told him. The jury found the defendant guilty. On appeal, the state concedes that the trial court erred in admitting the expert’s diagnosis in the absence of physical evidence, but argues that the error was harmless since other evidence speaks to the crime. The Court of appeals disagreed with the state, holding that the expert’s diagnosis was used to bolster complainant’s credibility, which could not be deemed harmless since the lynchpin of the state’s case was the complainant’s testimony surrounding the alleged incident. Reversed and remanded.