Abstract: This article analyzes familiar foreign relations law doctrines through the lens of rules and standards. The main, but not exclusive, focus is on the political question doctrine, the act of state doctrine, and dormant foreign affairs preemption. Prior to the 1960s, courts applied these doctrines in a highly formalistic fashion. Beginning in the 1960s, courts embraced a more instrumental and functional approach to these doctrines. I call this approach the foreign relations effects test. Under the foreign relations effects test, federal courts in their discretion identify and assess the foreign relations interests of the United States and make predictions about the effect of certain acts (by a federal court or a state) on these relations. They typically do this in the absence of guidance from the political branches. On the basis of such an independent foreign policy analysis, courts accommodate these interests through abstention, special interpretive canons, federal common law, or preemption as they best saw fit. The article has two main aims. The first is to identify and analyze the foreign relations effects test. The test rests on questionable assumptions about the nature of foreign relations law and the proper role of federal courts. It purports to protect political branch prerogatives in foreign relations, but it has the ironic consequence of enhancing the federal courts' power to make foreign relations law at the expense of the political branches. The second aim of the article is to identify and analyze a "new formalism" that has, in recent years, replaced the foreign relations effects test. The new formalism is not a return to conceptualism. Nor is it an attempt to mask value judgments by reference to legal materials. The new formalism is a pragmatic approach to judicial foreign relations doctrines based on analysis of comparative institutional competence and likely political branch response to various judicial decision-making strategies. The new formalism rejects the case-by-case judge-made foreign relations effects test. It aims to protect political branch prerogatives in non-constitutional foreign relations cases through the use of rules rather than standards. The best of these rules encourage the federal political branches with superior competence and a superior democratic pedigree to clarify the content of U.S. foreign relations law.