In Islands of Sovereignty, anthropologist and legal scholar Jeffrey S. Kahn offers a new interpretation of the transformation of US borders during the late twentieth century and its implications for our understanding of the nation-state as a legal and political form. Kahn takes us on a voyage into the immigration tribunals of South Florida, the Coast Guard vessels patrolling the northern Caribbean, and the camps of Guantánamo Bay—once the world’s largest US-operated migrant detention facility—to explore how litigation concerning the fate of Haitian asylum seekers gave birth to a novel paradigm of offshore oceanic migration policing. Combining ethnography—in Haiti, at Guantánamo, and alongside US migration patrols in the Caribbean—with in-depth archival research, Kahn expounds a nuanced theory of liberal empire’s dynamic tensions and its racialized geographies of securitization. An innovative historical anthropology of the modern legal imagination, Islands of Sovereignty forces us to reconsider the significance of the rise of the current US immigration border and its relation to broader shifts in the legal infrastructure of contemporary nation-states across the globe.