Revisiting the unanimity requirement: The behavior of the non-unanimous civil jury

I. INTRODUCTION Legal scholarship in the twenty-first century reflects a growing interest in behavioral research on law and legal institutions.1 In this Essay, we turn to behavioral research on the jury and use a unique set of real jury deliberations to raise serious questions about the trend toward dispensing with the unanimity requirement in civil jury trials. Recognition of empirical scholarship has deep roots at Northwestern, and empirical studies appeared alongside doctrinal legal scholarship even in the early issues of the Northwestern University Law Review. In a 1909 article, Northwestern's Dean Wigmore presented a fictional trial of Professor Hugo Muensterberg who, reflecting enthusiasm for his emerging discipline of experimental psychology,2 had overstated what psychology at that point could offer the legal system and had purportedly libeled the legal profession for its neglect of psychological science.3 Although the Wigmore article is often remembered as an attack on Muensterberg, Wigmore also used the fictional trial to urge the legal profession to form a "friendly and energetic alliance of psychology and law."4 In the century since Wigmore's article was published, both psychological research on legal issues and legal interest in that research have made substantial strides, although the struggle continues.5 In 1939, the Law Review published another early engagement with empirical scholarship, a pioneering-albeit rudimentary-empirical study by Professor Fred Inbau that tested the ability of lay persons (Northwestern law professors!) and professional document examiners to distinguish between genuine and forged signatures.6 That study presaged a debate about the alleged expertise of document examiners that later took on even greater importance in the wake ofDaubert v. Merrell-Dow Pharmaceuticals, Inc.1 This centennial issue of the Northwestern University Law Review reflects the most recent generation of empirical scholarship at Northwestern. In addition to this article on the behavior of the non-unanimous civil jury, the issue includes a number of other essays that describe findings from empirical studies.8 Few institutions in society require unanimity to reach a decision. Yet the unanimity requirement for jury verdicts was settled law in the latter half of the fourteenth century.9 Most of the American colonies adopted the British tradition, and the requirement of unanimity remained a standard feature of the American jury trial for both criminal and civil cases through most of the nineteenth century. Over time, a few exceptions appeared, particularly for civil trials. Today, jury verdicts in felony trials must be unanimous in federal courts10 and in all states except Louisiana and Oregon." The unanimity standard, however, has significantly eroded for verdicts in civil cases. Federal juries must be unanimous,12 but only eighteen states require unanimity and another three accept a non-unanimous verdict after six hours of deliberation.13 The remaining states permit super-majorities of between two-thirds and five-sixths in civil cases. In a recent resurgence of support for unanimous jury verdicts, the American Bar Association ("ABA"), in its Principles for Juries and Jury Trials adopted in 2005, endorses unanimity as an optimal decision rule for both criminal and civil jury trials.14 ABA Principle 4A states: "In civil cases, jury decisions should be unanimous wherever feasible."15 Nonetheless, the standard does allow for a non-unanimous verdict from a jury in a civil case after a reasonable period of deliberation if five-sixths of the jury and at least six jurors concur in the verdict.16 Supporters and critics of the unanimity requirement have debated its merits by drawing on history and precedent,17 but they have grounded much of their disagreement on conflicting claims about how the various decision rules are likely to affect jurors, jury deliberations, and jury verdicts. …