Abstract
Hart proposed that law is made possible by the practice among legal officials of observing conventional social rules, the most important being rules of recognition. This view has been dubbed the practice theory, and it has been attacked by many legal theorists. This paper argues that many criticisms of the practice theory fail because they misunderstand the nature of the organizational challenge to which rules of recognition are the solution. The challenge of constituting a legal system is essentially the challenge of constituting a group agent, and when viewed through Pettit’s account of group agency, the practice theory can easily be defended.