The Problem of the Expert Juror

Abstract:     
A fundamental principle of the Anglo-American adjudicative system is that cases must be decided based solely on evidence formally admitted through trial procedures. A jury may not base its decision on information received outside of those formal procedures. Yet jurors bring to the jury room a wealth of education and experience received prior to their service and not subject to the formal rules of proof. That kind of worldly knowledge is a prerequisite to jury service; without a basic level of common knowledge, jurors could not understand the evidence put before them. Problems can arise, however, when jurors bring expertise that exceeds the common knowledge that we expect, and need, them to have. This prospect raises the problem of the expert juror. Especially today, in an evidentiary system remade to require greater scrutiny of expert testimony, courts must be aware of the possibility that jurors will inject unexamined expertise into deliberations, thus subverting the adversarial model of proof we depend on for decisional accuracy and legitimacy. This article examines the problem of juror expertise and suggests an approach for addressing the problem that focuses first on jury selection and second, in extreme cases, on post-verdict review.

Accepted Paper Series