The Problem of the Expert Juror

In this article, I argue that the new focus on the risks of spurious "expertise" compels attention to the problem of juror expertise. 24 Specialized knowledge poses the same risks to the truth-seeking objectives of trial whether it enters the decision-making process through expert testimony or through the back door of juror background knowledge. In fact, the risks to accuracy may be less when expertise is offered by a witness than when it is introduced by a juror, because the witness will be subject to cross-examination and rebuttal. Flawed expertise brought to the case by a juror is not subject to cross-examination or rebuttal, and in most cases is entirely hidden from view. It thus poses special risks in criminal cases-even beyond the threat to accuracy-because of criminal defendants' constitutional rights to be confronted with and to confront the evidence against them.