State of Missouri v. Kane Carpenter

Summary

The Supreme Court of Missouri held that the statutory expert-testimony standard displaced prior common-law restrictions that had generally barred expert testimony about eyewitness-identification reliability. Because the proposed testimony was scientifically reliable, would have helped the jury evaluate the victim's identification, and would not have invaded the jury's role, the circuit court erred in excluding it. The error was prejudicial because the prosecution's case depended heavily on the victim's identification after a suggestive show-up, so the conviction was vacated and the case remanded for a new trial.