The Great Engine that Couldn't: Science, Mistaken Identifications, and the Limits of Cross-Examination

Abstract

Wigmore's assertion that cross-examination is the greatest engine for the search for the truth comes with a caveat: it works best for the untruthful witness, or for eliciting facts known to the witness but not acknowledged on direct examination. In the typical eyewitness-based prosecution, neither condition obtains. The eyewitness is not untruthful but may be mistaken; and eyewitnesses do not know the factors [weapons focus, the deleterious effect of stress on eyewitness accuracy, the problem of "own-race bias" in cross-racial crimes] that may have caused the mistake. This article traces cross-examination to its origins and demonstrates that its utility (as originally intended and as developed over centuries) is limited in eyewitness cases. The article concludes that other tools - better jury instructions, and the use of expert witnesses - are essential to ensure a complete search for truth in identification cases.