This article provides a comprehensive survey of the economic theory of public enforcement of law, focusing on the use of public agents to detect and sanction violators of legal rules. The authors present the basic elements of the theory, including the probability of imposing sanctions, the magnitude and form of sanctions, and the rule of liability. They then explore various extensions of the central theory, such as accidental harms, costs of imposing fines, errors, general enforcement, marginal deterrence, the principal-agent relationship, settlements, self-reporting, repeat offenders, imperfect knowledge about the probability and magnitude of fines, and incapacitation. The article aims to systematically and comprehensively address the economic theory of public enforcement, providing insights into how society should allocate resources for apprehending injurers and the optimal structure of sanctions. The authors also discuss the rationale for public versus private enforcement, emphasizing the importance of information about the identity of violators and the challenges of private enforcement. The article concludes with a summary of the main points and a discussion of public enforcement in practice.This article provides a comprehensive survey of the economic theory of public enforcement of law, focusing on the use of public agents to detect and sanction violators of legal rules. The authors present the basic elements of the theory, including the probability of imposing sanctions, the magnitude and form of sanctions, and the rule of liability. They then explore various extensions of the central theory, such as accidental harms, costs of imposing fines, errors, general enforcement, marginal deterrence, the principal-agent relationship, settlements, self-reporting, repeat offenders, imperfect knowledge about the probability and magnitude of fines, and incapacitation. The article aims to systematically and comprehensively address the economic theory of public enforcement, providing insights into how society should allocate resources for apprehending injurers and the optimal structure of sanctions. The authors also discuss the rationale for public versus private enforcement, emphasizing the importance of information about the identity of violators and the challenges of private enforcement. The article concludes with a summary of the main points and a discussion of public enforcement in practice.