Discretion, Delegation, and Defining in the Constitution\u27s Law of Nations Clause

Never in the nation\u27s history has the scope and meaning of Congress\u27s power to Define and Punish. . . Offenses Against the Law of Nations mattered as much. The once obscure power has in recent years been exercised in broad and controversial ways, ranging from civil human rights litigation under the Alien Tort Statue (ATS) to military commissions trials in Guantanamo Bay. Yet it has not yet been recognized that these issues both involve the Offenses Clauses, and indeed raise common constitutional questions.First, can Congress only Define offenses that clearly already exist in international law, or does it have discretion to codify debatable, embryonic, or even nonexistent international law norms? Second, assuming Congress does have creative leeway under the Offenses Clause, what happens to this discretion when it delegates the power to a coordinate branch? Ironically, the Offenses Clause has cross-cutting political implications: a narrow understanding of the power limits the crimes that can be tried before military commissions, but also forecloses much human rights litigation under the ATS. This Article shows that Offenses Clause only allows Congress to Define -- to specify the elements and incidents of - offenses already created by customary international law. It does not allow Congress to create entirely new offenses independent of preexisting international law. At the same time, the Framers understood international law to be vague and intertwined with foreign policy considerations. Reasonable people can widely disagree about what international law is and requires. Thus courts reviewing congressional definitions should give them considerable deference. Moreover, whatever discretion Congress has in defining offenses disappears when it broadly delegates that power to another branch, as it has in the ATS. Thus courts can only recognizes causes of action under the ATS for the most well-established and clearly defined international crimes. The Supreme Court suggested a similar standard for ATS causes of action in Sosa v. Alvarez-Machain. Appreciating the role of delegation in the ATS shows that the limits on offenses that can be litigated under the statute have a constitutional dimension. The Article develops the original understanding of the Offenses Clause -- particularly important given the lack of any judicial decisions on it in the nation\u27s first century. It draws on previously unexplored sources, such as early cases about the meaning of the Define power in the cognate context of piracy and felonies; legislation by early Congresses exercising - or refusing to exercise -- the Offenses power -- and discussions by Framers like Madison and others