Each of the Restatements of Foreign Relations Law published by the American Law Institute has sought to promote the rule of law. It is easy to endorse this goal, but promoting the rule of law is more complicated than it may initially appear. This chapter surfaces some of the tensions that are built into the project of reaffirming or promoting the rule of law. To start, there are at least three distinct ways that Restatements of foreign relations law might promote the rule of law. They might do so by clarifying the content of the law; by contributing to the development of new legal rules, in particular to the evolution and consolidation of customary international law; and by promoting compliance with the law. The Third and Fourth Restatements have taken quite different approaches to promoting the rule of law. To some extent these different approaches are a consequence of changes in the legal landscape over the past three decades. They also reflect different choices that the reporters and the American Law Institute have made about how to carry out the project of restating foreign relations law. The chapter begins by identifying developments in U.S. case law that have begun to drive a wedge between promoting the rule of domestic law and promoting compliance with international law. The chapter then turns to the diverging approaches of the Third and Fourth Restatements with respect to customary international law. The Third Restatement is notably quick – according to some critics, too quick – to articulate rules of customary international law. In doing so, the reporters of the Third Restatement were quite willing to disagree with the views of the U.S. government. By contrast, the Fourth Restatement is more reticent on both fronts. The approach taken by the Fourth Restatement avoids some of the downsides of that taken by its predecessor, but also forfeits some of the advantages. The chapter closes by arguing that future installments of the Fourth Restatement ought to promote the rule of international law by updating and expanding the sections of the Third Restatement that address the architecture of international law on two key issues: international responsibility and how customary international law evolves over time. The Fourth Restatement need not directly exhort litigants and judges to comply with international law. But by providing this basic information about the international legal system, the Restatement would wave a caution flag and encourage courts to take the procedural steps that would avoid unwitting (and potentially deleterious) engagement with international law.