The jurisprudence of sport is a recent area of study in the philosophy of sport and in law. It views sports as systems of rules, akin to state legal systems. There are umpires/referees who adjudicate and issue penalties on the field of play. And the rules of cricket, rugby, and association football are called ‘laws’ with good reason. The structure and nature of sports are usually much easier to grasp than a fully-fledged legal system. As a result, lawyers can learn much from them. But the law can equally illuminate contentious questions in sports when philosophers of sport apply well-established legal categories (primary and secondary rules, compensation versus restitution, excuse versus justification, etc.) to games. Since the end of the 20th century, there has been a growing literature and interest in the subject. This entry follows that trajectory.