AbstractRules of jurisdiction and immunity are central to public international law, and equally vital to the United Nations Convention on the Law of the Sea (LOSC). The LOSC established an extensive framework to regulate legislative and enforcement jurisdiction over ocean space, one that has proven to be remarkably durable, despite lingering uncertainties in the compromise reached between coastal and maritime states. State practice diverging from the LOSC’s jurisdictional scheme has been isolated and infrequent, and the scheme has been strengthened and elaborated by regional and global treaties addressing contemporary oceans governance challenges, especially in the arenas of pollution control and fisheries management. As the LOSC turns thirty, a key challenge will be keeping in check the designs of coastal states over adjacent maritime space as they look seawards to address pressing concerns of resource, food, energy and environmental security.