The constitutionality of international courts: The forgotten precedent of slave-trade tribunals

The United States' participation in international courts and, in particular, its potential accession to the International Criminal Court (ICC), a court that would have jurisdiction over U.S. nationals and U.S. territory, raise 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 nineteenth century, an episode that has never before been examined for its relevance to current legal and policy debates. This Article presents that historical debate and draws lessons for the present. The permissibility of the United States joining international tribunals spans several major constitutional issues: the delegation of federal powers to supernational institutions; the limits, if any, on what the treaty power can do; and the vesting of judicial power in non-Article III courts. While these are all famously confused and contentious areas of law, the preponderance of scholarly opinion concludes that the Constitution does not bar the United States from joining international courts, including the ICC. The jurisprudence and literature on these questions, however, have neglected an important precedent. In the wake of the Napoleonic Wars, a network of international tribunals to punish slave trading was 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 fortyfive years, a period that spanned eleven presidencies. Constitutional objections were formulated by some of the leading statesmen of the early Republic and even by some members of the founding generation. They were unanimous in their view that the Constitution forbids joining an international criminal court with jurisdiction over American nationals. They raised several constitutional objections of both structural and individual-rights varieties. The United States complained, in a long series of diplomatic missives, that such a court's decisions would not be reviewable by the Supreme Court and that, even more importantly, the court would subject U.S. nationals to criminal trials without a jury and other Bill of Rights protections. These objections were unanimously held in James Monroe's distinguished Cabinet, shared by Congress, and undisputed by anyone for decades. This Article examines the constitutional objections stated at the time of the slave-trade courts and shows that some, but not all, international criminal courts are likely to be unconstitutional, while noncriminal international tribunals are far less problematic. The foregoing suggests that it would be unconstitutional to join an international criminal court with jurisdiction over certain offenses, some of which are within the ICC's charter. The evidence presented here can guide the tailoring of such courts' jurisdiction to avoid constitutional conflicts. 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 such as 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 concerning the conflict between domestic and international law was rehearsed nearly two hundred years ago.