The Constitutionality of International Courts : The Forgotten Precedent of Slave Trade Tribunals

The United States' participation in international courts, and in particular, the potential accession to the International Criminal Court (ICC), which would have jurisdiction over U.S. nationals and U.S. territory, raises serious constitutional questions. These questions were thoroughly analyzed in the course of the debate about the constitutionality of international courts proposed by Britain in the early 19th century. This episode has never been examined by legal scholars or historians, despite its great relevance to a current legal and policy debates. This Article presents that historical debate over the slave trade courts, and draws lessons for the present legal questions. The permissibility of joining international tribunals spans several major constitutional issues: delegating federal powers to supernational institutions; the limits if any on what can be done through the Treaty Power; and vesting judicial power in non-Article III courts. While these are all famously confused and contentious areas of law, a preponderance of scholarly opinion concludes that the Constitution does not bar joining international courts, the ICC included. However, the jurisprudence and literature on these questions has entirely neglected an important evidence. In the wake of the Napoleonic Wars, a network of international tribunals to punish slave trading as created. Many European nations joined these "mixed courts." The United States, however, saw the courts as unconstitutional. It refused to join the mixed court system for forty-five years, spanning eleven presidencies. The constitutional objections were formulated by some of the leading statesmen of the early Republic, and even some members of the Founding Generation. They raised several constitutional objections of both structural and individual rights varieties: that the court would not be reviewable by the "Supreme" Court; and, even more importantly, that it would subject U.S. nationals to criminal trials without jury trial and other Bill of Rights protections. These objections were held unanimously in the distinguished Cabinet of James Monroe; shared by Congress; and undisputed by anyone for decades. This suggests that giving an international criminal court jurisdiction over certain offenses within the ICC's charter would be unconstitutional. This does not mean that U.S. participation in international criminal courts would always be unconstitutional. Those interested in seeing the United States participate in such courts will find in the slave trade court episode not a constitutional straitjacket but rather a guide to tailoring their jurisdiction to avoid constitutional constraints. This Article unpacks the constitutional objections stated at the time and shows that some but not all international criminal courts are likely to be unconstitutional, while non-criminal international tribunals are far less problematic. Aside from the precedential significance, the nineteenth century discussion of why joining such a court would be impermissible speaks directly to today's constitutional jurisprudence in modern terms. It provides surprisingly relevant guidance on questions like the permissibility of non-Article III courts; constitutional restraints on the Treaty Power; and the binding effect of judgments of international courts. Additionally, nearly every argument made today about American exceptionalism in international law and the conflict between domestic and international law was rehearsed nearly 200 years ago