In Part I, the Article discusses the history of the U.S. Supreme Court’s substantive due process limitations on personal jurisdiction and, in particular, the standards for corporate-activities-based jurisdiction before the Court’s recent cases on that issue. Part II discusses the Court’s failure to provide a convincing theoretical justification for imposing substantive due process limitations on personal jurisdiction. It also discusses the consequences of that failure in three doctrinal areas of personal jurisdiction law, the traditional basis of service on an individual in the forum state, specific jurisdiction and corporate-activities-based jurisdiction. Part III then analyzes in detail the four recent Supreme Court cases on personal jurisdiction, and discusses the mistaken assumptions underlying those decisions. Part IV explains how the Court’s personal jurisdiction rules, as a whole, suffer from theoretical bareness, the ambiguity of the substantive due process categories of jurisdiction, and the rigidity of the Court’s substantive due process analysis. Finally, in Part V, the Article offers some ideas for how the Court could begin to remedy the many problems with personal jurisdiction law.