This book explores the insights that can be gained by looking at the criminal justice system from an economic point of view. Such a perspective, of course, is not new; economists have been thinking about crime and punishment at least since the work of Montesquieu (1748), Beccaria (1764), and Bentham (1780). However, the subject was strangely neglected by economists for 200 years, until finally being revived by Gary Becker in his classic article on the economics of crime and punishment (Becker 1968). Now, as we embark on the second half-century since the publication of that path-breaking work, it would seem to be an opportune moment to assess its influence on both the scholarly literature and the practice of law enforcement. There is no dispute that Becker’s model has had a profound effect on the way economists think about criminal law. Indeed, it has begotten a massive literature that has culminated in a highly polished theory of the optimal structure of law enforcement. Perhaps because Becker’s objective was avowedly normative, however, the resulting insights have been somewhat less successful in describing the actual practice of criminal justice.