Economics explains legal compliance via sanctions, particularly by the ability of legal sanctions to change the cost of behavior and deter noncompliance. Yet rational choice tools predict other ways in which law influences behavior: by suggesting a means of coordination and by informing beliefs. First, when people seek to order their behavior with others, law provides a salient means of coordinating. Second, law reveals information about risks and attitudes, which prompts individuals to update their beliefs and alter their behavior. The coordination and information powers are law's expressive powers, as distinguished from its coercive powers. They explain the law's sometimes puzzling efficacy, such as when tribunals are able to arbitrate disputes without the power of sanctions or legitimacy.

Richard McAdams is Bernard D. Meltzer Professor of Law and Aaron Director Research Scholar at the University of Chicago Law School. This talk, the 2014 Coase Lecture in Law and Economics, was recorded on April 15, 2014.