For too long, state interests have dominated public jurisdiction and private choice of law analyses regarding the reach and application of a state’s law, or prescriptive jurisdiction. Individual rights— whether of criminal defendants or private litigants—have been marginalized. Yet states are projecting regulatory power over actors abroad with unprecedented frequency and aggression. State interest analyses proceed from the perennially critiqued but remarkably sticky concept of sovereignty. Now more than ever, legal thinkers, courts, and litigants need a bedrock concept from which to build individual rights arguments against jurisdictional overreach. And it should be one that holds not only theoretical cogency but also the promise of real-world traction in cases. This Article introduces the concept of spatial legality. It recasts the familiar and deeply rooted notion of legality—that is, the idea of fair notice of the law—along spatial as well as temporal dimensions. Operating in time, legality vindicates individual rights, for example by prohibiting ex post facto laws. Spatial legality focuses on law’s reach in space rather than its existence in time, but the problem is essentially the same: someone is being subjected to a law he could not reasonably have expected would govern his conduct when he engaged in it. The Article begins by taking extant rules of jurisdiction in multistate systems and transforming them through the concept of spatial legality into a right to fair notice of the law applicable at the time of conduct. It then shows how a jurisdictional mix-up metastasizing in both U.S. and international law is presently aggravating spatial legality problems: namely, the use of personal jurisdiction over parties to bootstrap application of substantive law to their extraterritorial conduct. The mix-up occurs (1) on the criminal side, by using a defendant’s postconduct presence in the forum to justify applying substantive law to prior conduct outside the forum, and (2) on the civil side, by using “general” personal jurisdiction over parties to justify applying forum law to activity outside the forum. Reorienting jurisdictional doctrine around the rights of parties instead of states generates important doctrinal and litigation payoffs: it clarifies and straightens out the law for courts and, where courts do err, supplies parties with rights-based arguments to challenge such errors as opposed to state-based arguments about sovereignty and comity. In this connection, the Article proposes a typology that weaves together public jurisdiction and private choice of law doctrines to identify how and when spatial legality claims will have the most traction on the current state of the law. It concludes by indicating the limits of a spatial legality concept based only on notice and suggests other rule of law criteria like feasibility of compliance, avoidance of contradictory laws, and consistency that, going forward, may further inform analysis of the demands multistate systems with overlapping laws place on fundamental fairness.