Untangling the Causal Effects of Sex on Judging


  • Christina L. Boyd is Assistant Professor in the Department of Political Science, University at Buffalo, SUNY, 520 Park Hall, Buffalo, NY 14260 (cLboyd@buffalo.edu). Lee Epstein is Henry Wade Rogers Professor, Northwestern University School of Law, 357 E. Chicago Ave., Chicago, IL 60611 (lee-epstein@northwestern.edu). Andrew D. Martin is Professor in the Department of Political Science and School of Law, Washington University in St. Louis, Campus Box 1063, One Brookings Drive, St. Louis, MO 63130 (admartin@wustl.edu).

Winner of the 2008 Pi Sigma Alpha award for the best paper presented at the annual meeting of the Midwest Political Science Association. We thank the Center for Empirical Research in the Law, the Weidenbaum Center at Washington University, the National Science Foundation, the Baldy Center for Law & Social Policy, and the Northwestern University School of Law for supporting our research; Cass Sunstein, David Schkade, Lisa M. Ellman, and Andres Sawicki for sharing their data; Shari Diamond, Sarah Fischer, William Landes, Kevin Quinn, Richard Posner, Nancy Staudt, Kim Yuracko, the editor and anonymous reviewers of the American Journal of Political Science, and participants at faculty workshops at Dartmouth College, Stony Brook University, the University of Chicago, the University of Illinois, the University of Pennsylvania, and Washington University for providing useful comments; and Delia Bailey, Kathryn Jensen, Hyung Kim, Zachary Levinson, Jessica Silverman, and Jennifer Solomon for supplying excellent research assistance. The project's web site (http://epstein.law.northwestern.edu/research/genderjudging.html) houses a full replication archive, including the data and documentation necessary to reproduce our results.


We explore the role of sex in judging by addressing two questions of long-standing interest to political scientists: whether and in what ways male and female judges decide cases distinctly—“individual effects”—and whether and in what ways serving with a female judge causes males to behave differently—“panel effects.” While we attend to the dominant theoretical accounts of why we might expect to observe either or both effects, we do not use the predominant statistical tools to assess them. Instead, we deploy a more appropriate methodology: semiparametric matching, which follows from a formal framework for causal inference. Applying matching methods to 13 areas of law, we observe consistent gender effects in only one—sex discrimination. For these disputes, the probability of a judge deciding in favor of the party alleging discrimination decreases by about 10 percentage points when the judge is a male. Likewise, when a woman serves on a panel with men, the men are significantly more likely to rule in favor of the rights litigant. These results are consistent with an informational account of gendered judging and are inconsistent with several others.