This article studies the normative universe of the actors of an Ancien Régime fishing community, through the case of eighteenth-century Dieppe. The first section presents the functioning and activity of the local admiralty court, which, during the Ancien Régime, exercised exclusive jurisdiction over maritime affairs and, as such, heard disputes between members of the fishing community, such as shipowners, masters, and seamen. Whereas French maritime historiography has for a long time focused on the supervisory and monitoring roles attributed to this jurisdiction, legal practice archives paint a different picture. The overwhelming majority of cases brought before the admiralty officers actually involved minor conflicts resulting from fishing accidents, broken contracts, or unpaid wages—in other words, civil proceedings. Nevertheless, a close examination of these disputes allows us to shed light on the social uses of justice made by the litigants. Far from simply being an instrument of control of the coastline and its population, the admiralty court fulfilled functions that largely exceeded the mere resolution of labor conflicts; they also took on the certification of contracts or the expert assessment of damages. The final part of the paper takes as a starting point the plurality of normative systems in effect in Ancien Régime fishing communities and shows how it is possible to consider the admiralty court as both a local arena in which norms were (re)negotiated by the actors themselves, and as a legal laboratory that produced a local law “from below.”