A Normality Bias in Legal Decision Making

Cornell Law Review, Vol. 88, p. 583, 2003

69 Pages Posted: 12 Jul 2009 Last revised: 30 Jun 2015

Date Written: 2003


It is important to understand how legal fact finders determine causation and assign blame. However, this process is poorly understood. Among the psychological factors that affect decision makers are an omission bias (a tendency to blame actions more than inactions [omissions] for bad results), and a normality bias (a tendency to react more strongly to bad outcomes that spring from abnormal rather than normal circumstances). The omission and normality biases often reinforce one another when inaction preserves the normal state and when action creates an abnormal state. But what happens when these biases push in opposite directions as they would when inaction promotes an abnormal state or when action promotes a normal state? Which bias exerts the stronger influence on the judgments and behaviors of legal decision makers? The authors address this issue in two controlled experiments. One experiment involves medical malpractice and the other involves stockbroker negligence. They find that jurors pay much more attention to the normality of conditions than to whether those conditions arose through acts or omissions. Defendants who followed a nontraditional medical treatment regime or who chose a nontraditional stock portfolio received more blame and more punishment for bad outcomes than did defendants who obtained equally poor results after recommending a traditional medical regime or a traditional stock portfolio. Whether these recommendations entailed an action or an omission was essentially irrelevant. The Article concludes with a discussion of the implications of a robust normality bias for American jurisprudence.

Keywords: Causation, omission bias, jurors

Suggested Citation

Koehler, Jonathan J. and Prentice, Robert A., A Normality Bias in Legal Decision Making (2003). Cornell Law Review, Vol. 88, p. 583, 2003, Available at SSRN: https://ssrn.com/abstract=1432073

Jonathan J. Koehler (Contact Author)

Northwestern University - Pritzker School of Law ( email )

375 E. Chicago Ave
Chicago, IL 60611
United States

Robert A. Prentice

University of Texas at Austin - McCombs School of Business ( email )

Austin, TX 78712
United States

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