Treaties as Laws: A Defense of the Last in Time Rule for Treaties and Federal Statutes

73 Pages Posted: 4 Nov 2004

See all articles by Julian Ku

Julian Ku

Hofstra University - School of Law


For nearly 150 years, courts have applied the last in time rule to resolve conflicts between treaties and federal statutes by giving effect to whichever was enacted later in time. Despite its acceptance by the courts, this rule has received unanimous criticism in the legal academy. In this article, I present the first comprehensive defense of the last in time rule on textual, structural, historical, and functional grounds. I argue that the last in time rule should be applied because the text of the Constitution grants treaties the status of enacted domestic law. As such, treaties are subject to the principle of statutory construction, leges posteriors priores contrarias abrogant (later laws abrogate prior laws that are contrary), unless otherwise indicated by the Constitution's text or structure. This understanding is supported by Supreme Court precedent, historical evidence from the Founding era, including practice during the pre-Constitution era, discussions during the Constitutional Convention and ratifying debates, as well as actions during the early years of the Constitutional era. In the course of defending the last in time rule, I also consider how the rule fits into the broader debate over the extent to which treaties, which increasingly seek to regulate traditionally domestic matters, have effect in the U.S. legal system. The last in time rule, I contend, provides an elegant compromise between internationalists seeking greater incorporation of treaties and revisionists seeking to limit or eliminate such incorporation. Under the last in time rule, treaties are given direct domestic effect, which facilitates greater U.S. participation in the international system. On the other hand, the last in time rule guarantees that a politically accountable Congress retains the flexibility to control a treaty's domestic effects.

Keywords: Treaties, international law, constitutional law, statutory interpretation

JEL Classification: K3

Suggested Citation

Ku, Julian G., Treaties as Laws: A Defense of the Last in Time Rule for Treaties and Federal Statutes. Indiana Law Journal, Vol. 80, p. 319; Hofstra Univ. Legal Studies Research Paper No. 04-12. Available at SSRN:

Julian G. Ku (Contact Author)

Hofstra University - School of Law ( email )

121 Hofstra University
Hempstead, NY 11549
United States
516-463-4237 (Phone)
516-463-6264 (Fax)

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