This article introduces a Thematic Section and theorizes the multiple ways that judicializing international relations shifts power away from national executives and legislatures toward litigants, judges, arbitrators, and other nonstate decision-makers. We identify two preconditions for judicialization to occur-(1) delegation to an adjudicatory body charged with applying designated legal rules, and (2) legal rights-claiming by actors who bring-or threaten to bring-a complaint to one or more of these bodies. We classify the adjudicatory bodies that do and do not contribute to judicializing international relations, including but not limited to international courts. We then explain how rights-claiming initiates a process for authoritatively determining past violations of the law, identifying remedies for those violations, and preventing future violations. Because judicializing international relations occurs in multiple phases, in multiple locations, and involves multiple actors as decisionmakers, governments often do not control the timing, nature, or extent to which political and policy decisions are adjudicated. Delegation-and the associated choice of institutional design features-is thus only the first step in a chain of processes that determine how a diverse array of nonstate actors influence politically consequential decisions.