In the contemporary world, the domains of laws overlap a lot. With human activity (business, family, political, creative) unfolding at a greater distance as well as thickness, what people do increasingly implicates multiple sovereigns. Almost nothing important, whether it be a public act of a government or a transaction among private parties, goes forward without encountering overlapping domains. Assigning problems that arise in this behavior to particular legal domains is a pervasive issue.
What makes this issue immediately important, and not just a technical exercise in thinking about law, is the growth of the international-law enterprise over the last quarter-century. Both the ambitions and the institutions of international law expanded greatly in the decade after the collapse of the Soviet system. Even as they currently face assault from nationalist populists in the rich world and elsewhere, these institutions continue to play a critical role in many fields. Their influence means more frequent and more intrusive claims about the domain of international law to the derogation of national and subnational law. Such domain conflicts always existed, but they have grown in salience.
Rather than looking at the problem of international law nested within national legal systems in isolation, we can see this issue as a particular instance of the general problem of competition among sovereigns and the domains of their laws. Reframing the problem in this way lets us draw on a great body of practical experience. Legal actors wrestle with domain problems all the time and have worked out approaches that manage potential conflicts in a reasonably helpful fashion. As the ambitions of international law have grown, we see the same practice at work there.
This article offers the first systematic analysis of conflicts over domain assignments across different kinds of sovereignty. It provides five explanations for these patterns. The article begins by providing an account of the ways that domains overlap, the kinds of conflicts that may result, and how authoritative actors might resolve these conflicts. It proposes a rational-choice model that can explain consistent patterns of deference in domain assignments. The article then surveys the evidence in support of the model, drawing on examples from tax law, the law of federal courts, and international law. The article concludes by considering whether a systematic approach to domain assignments based on the rational interest of states should prevail. Why not give greater normative content to assignment rules?
Paul B. Stephan, Competing Sovereignty and Laws’ Domains, 45 Pepperdine Law Review, 239–330 (2018).