This chapter examines the ways in which global lawmakers increasingly seek to recognize and preserve governance systems embedded in tight-knit communities of fishers and based on social norms. These policymakers view the law as a device that dominates and empowers these governance systems. Based on the case study of a medieval institution that has governed the fishery of Marseille since the late Middle Ages (the Prud’homie de Pêche), this chapter argues that legal rules can deeply shape the identity of close-knit communities, and that the goal of recognizing the autonomy of social norms through legal rules might be premised on a fragile, albeit widespread, distinction between the legal and the social. The chapter’s central argument draws on the definition by law of a three-mile territorial zone, which has deeply shaped the system of governance by global lawmakers in the fishery of Marseille in ways that were neither intended nor expected.