Congress, the Supremacy Clause, and the Implementation of Treaties

127 Pages Posted: 27 Aug 2008 Last revised: 6 May 2009

Date Written: August 26, 2008


This article discusses the law of treaty implementation in the early United States, with particular reference to whether and when treaties are self-executing and the legitimacy of the last in time rule for conflicts between treaties and federal statutes.

Other writers have used historical materials to support a variety of claims about these topics. Relying on the most comprehensive analysis of the historical materials to date, this article takes issue with nearly all of these writers. Most importantly, I do not contend that historical materials provide conclusive answers to the problems of treaty implementation. Rather, my historical narrative demonstrates a far greater degree of ambiguity during the founding period on critical issues than other writers have admitted.

The lack of clear original intentions was particularly true at the separation of powers level, which meant that the role of the House in treaty-making and implementation remained unclear. Solutions to this problem emerged only through a series of debates in Congress. Subsequent Supreme Court decisions effectively ratified the most broad-based of those solutions. Indeed, the congressional debates shed important light on the interpretation of those decisions - an issue on which, once again, I depart from most commentators.

Seen in this light, the law of treaty implementation emerges as an area in which original understandings provide little help. Nor can the solutions reached in the early nineteenth century claim the status of immutable rules. Rather, the congressional debates provide an example for our own time. The ideas and issues that came to Congress provide a framework and context for a debate that is necessarily ongoing and open-ended. To that end, I suggest that the general terms of Congress's solution should continue to guide doctrine - not because of their pedigree, but because they accommodate the relevant interests in an appropriate manner.

Finally, I use these conclusions to sketch an assessment of the Supreme Court's recent decision in Medellin v. Texas.

Keywords: treaties, international law, constitutional law, supremacy clause, treaty power

JEL Classification: K33

Suggested Citation

Parry, John T., Congress, the Supremacy Clause, and the Implementation of Treaties (August 26, 2008). Fordham International Law Journal, Vol. 32, No. 4, 2009, Lewis & Clark Law School Legal Studies Research Paper No. 2009-7, Available at SSRN:

John T. Parry (Contact Author)

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