Territoriality is a defining attribute of the Westphalian state, the model upon which the framers of the US Constitution based their aspirations for a new nation. Under Westphalian principles the scope of a sovereign's law corresponds to the geographic boundaries of the sovereign's territory. Yet, it is indisputable that territoriality is decreasingly important as a jurisdictional principle. Since the 1940s, US statutes in a wide range of areas—antitrust, securities, criminal law, intellectual property, to name just some—have been frequently understood to have extraterritorial effect. Similarly, the protections of the Bill of Rights, once believed to apply only within US territory, now extend across the globe with regard to US citizens. In short, territoriality has been slowly unbundled from sovereignty. The relationship between law and territory—what I call legal spatiality—has changed. What explains this change? Although globalization is often said to reduce the centrality of territory to states, I argue that globalization vel non cannot adequately explain the decline of territorial doctrines of jurisdiction. Rather, it is the particular nature of the postwar wave of globalization coupled with fundamental changes in international security that have increased the incentives for states to assert their domestic law beyond their sovereign borders. The Treaty of Westphalia commonly, if mythically, denotes the birth of territorially based state sovereignty (Krasner 1999). The medieval order, broadly characterized, comprised multiple, layered power centers as well as diverse sources of legitimation, allegiance, and status (Bull and Watson 1984; Spruyt 1995). Westphalia introduced a conception of legal spatiality that was no longer status based but instead place based. Legal rules primarily corresponded to places, not to people. Historically, the Westphalian conception of spatiality has informed the treatment of US constitutional rights abroad. In 1880, on a US ship docked in Yokohama Bay, a sailor named John Ross killed a …