Numeracy and Legal Decision Making

41 Pages Posted: 18 Oct 2012 Last revised: 5 Oct 2013

See all articles by Arden Rowell

Arden Rowell

University of Illinois College of Law

Jessica Bregant

University of Houston Law Center

Date Written: July 1, 2013


Health and financial decision-making literatures have chronicled how people’s numerical abilities affect their decisions. Until now, however, there has been no empirical study of whether numeracy — or people’s ability to understand and use numbers — also interacts with legal decision making. This Article presents the first such study, and describes three original findings related to the role of numeracy in legal decision making. First, the study shows a surprisingly high level of math skill among law students, especially given the common folk wisdom that lawyers are bad at math. Second, although prior research in non-legal contexts has shown that people with low numeracy are particularly susceptible to cognitive bias, we detect no significant relationship between law students’ math skills and their susceptibility to bias or framing effects. Finally, and most worryingly, our findings show that the substance of legal analysis varies with math skill for at least some subset of cases.

Keywords: numeracy, math skill, legal decisionmaking, law and psychology, decision making, attorney or lawyer error, perception of risk, empirical legal studies, inefficient precautions, Hand formula

JEL Classification: D81, K00, K10, K13, K32, K1, K2, K3, K4, C00

Suggested Citation

Rowell, Arden and Bregant, Jessica, Numeracy and Legal Decision Making (July 1, 2013). Arizona State Law Journal, Vol. 46, No. 1, 2014, Illinois Public Law Research Paper No. 13-29, Illinois Program in Law, Behavior and Social Science Paper No. LBSS14-01, Available at SSRN: or

Arden Rowell (Contact Author)

University of Illinois College of Law ( email )

504 E. Pennsylvania Avenue
Champaign, IL 61820
United States

Jessica Bregant

University of Houston Law Center ( email )

4604 Calhoun Road
Houston, TX 77204
United States

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