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Harvard International Law Journal


Many commentators who favor expansions in international law also favor restrictions on executive authority. What these commentators often fail to recognize is the potential for conflict between these two commitments. In this Article, I consider one example of this potential conflict: the effect under international law of signed but unratified treaties.

Under contemporary treaty practice, a nation’s signature of a treaty, especially a multilateral treaty, typically does not make the nation a party to the treaty. Rather, nations become parties to treaties by an act of ratification or accession, either by depositing an instrument of ratification or accession with a depositary (for multilateral treaties) or exchanging instruments of ratification (for bilateral treaties). The signing of treaties under this practice is at most an indication that the terms of the treaty are satisfactory to the executive institution in that nation charged with negotiating and signing treaties and does not constitute a promise that the nation will become a party to the treaty.

Despite the modern separation between signature and ratification, many international lawyers and academics contend that when a nation signs a treaty, it is bound to refrain from actions that would defeat the object and purpose of the treaty until such time as it makes clear its intention not to become a party to the treaty. This obligation is reflected in Article 18 of the Vienna Convention on the Law of Treaties (“Vienna Convention”), a treaty that itself governs the formation, interpretation, and termination of treaties. Although the United States is not a party to the Vienna Convention, many commentators claim that Article 18 reflects customary international law that is binding on nations that have not joined the Convention, a claim that the United States has not denied.1 In addition, some commentators have made broad claims about the content of the object and purpose obligation, arguing that it either binds signatory nations not to violate a treaty at all or that it binds them not to violate any of the “core” or “important” provisions in the treaty.2 These claims are frequently made, for example, in connection with the U.S. signature of human rights treaties, such as the Convention on the Rights of the Child.3

Treaties are signed for the United States by the president and his agents. As a result, any international obligations that the United States would incur as a result of signing a treaty would be triggered by unilateral executive action. This sort of unilateral executive authority, however, appears to be in tension with the process specified in Article II of the Constitution for making treaties, which requires the advice and consent of two-thirds of the Senate.4 As I will explain, this tension is not eliminated by the existence of the president’s power to enter into “sole executive agreements.” Whatever its precise scope, the sole executive agreement power must be significantly narrower than the power to enter into Article II treaties.

The extent of this constitutional tension, however, depends on the breadth of the signing obligation. The drafting history of Article 18 suggests that the signing obligation was intended to be narrower than some commentators have assumed. This obligation is best construed as precluding only actions that would substantially undermine the ability of the parties to comply with, or benefit from, the treaty after ratification. Considered in these terms, the obligation has little relevance to many types of treaties, such as human rights treaties, where preratification conduct inconsistent with the treaty is not likely to undo the bargain reflected in the treaty. Adopting this narrow interpretation of the object and purpose obligation helps reduce the gap between presidential authority under the Constitution and international law. Nevertheless, because there is still some potential for constitutional conflict, and because the object and purpose obligation is undefined in the text of the Vienna Convention, the Senate should be attentive to this issue if it is to preserve its already diminished role in the treaty process.

Part I of this Article describes the phenomenon of signed but unratified treaties and discusses some of the reasons for this phenomenon. Part II discusses the effect under modern international law of signing a treaty and explains how some commentators have claimed that signing a treaty obligates the United States either to comply with the treaty in its entirety or to comply with the “core” or “important” terms of the treaty. Part III argues that broad obligations arising from signature are in tension with the U.S. constitutional process for making treaties, and that this tension is not eliminated by the president’s power to conclude sole executive agreements. Part IV explains how the drafting history of Article 18 of the Vienna Convention suggests that the scope of the object and purpose obligation is narrower than is sometimes assumed, thus resolving some of the constitutional tension posed by signing obligations.

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