Nothing But the Truth? Experiments on Adversarial Competition, Expert Testimony, and Decision Making


  • This article was presented at the Conference on Empirical Legal Studies at New York University, 2007. We thank Jennifer Arlen, Geoffrey Miller, and Ted Eisenberg for their generous invitation to present our work at that conference. We also thank the National Science Foundation, Grant SES-0616904, the Kavli Institute for Brain and Mind, and the Chancellor's Associates Chair VIII at UC San Diego for providing financial support for these experiments. We are also grateful to William Heller, Scott MacKenzie, Rebecca Morton, Jeff Rachlinski, Dan Rodriguez, Joel Sobel, Matthew Spitzer, Jeff Staton, Lydia Tiede, and members of the University of San Diego Law School for helpful comments on an earlier draft of this article.

*Cheryl Boudreau, University of California, Davis, Department of Political Science, One Shields Ave., Davis, CA 95616; email: Boudreau is Assistant Professor of Political Science, University of California, Davis. McCubbins is Chancellor's Associates Chair of Political Science, University of California, San Diego; Visiting Professor of Law, University of Southern California; Adjunct Professor of Law, University of San Diego.


Many scholars debate whether a competition between experts in legal, political, or economic contexts elicits truthful information and, in turn, enables people to make informed decisions. Thus, we analyze experimentally the conditions under which competition between experts induces the experts to make truthful statements and enables jurors listening to these statements to improve their decisions. Our results demonstrate that, contrary to game theoretic predictions and contrary to critics of our adversarial legal system, competition induces enough truth telling to allow jurors to improve their decisions. Then, when we impose additional institutions (such as penalties for lying or the threat of verification) on the competing experts, we observe even larger improvements in the experts' propensity to tell the truth and in jurors' decisions. We find similar improvements when the competing experts are permitted to exchange reasons for why their statements may be correct.