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Unpublished Paper
Conditions in U.S. Treaty Practice: New Data and Insights into a Growing Phenomenon
ExpressO (2015)
  • Cindy G. Buys

The U.S. Senate often adds various types of conditions, also known as reservations, understandings, and declarations, to its advice and consent to multilateral treaties. The ability to add conditions to a treaty likely increases the number of States willing to join a treaty because it allows States to modify their treaty obligations to address domestic concerns. However, the use of conditions also has the potential to undermine the integrity of the treaty by allowing States to opt out of important legal obligations and to create legal uncertainty regarding treaty obligations and relationships. This article examines U.S. treaty practice with respect to the use of conditions to determine how and when conditions are being used and the effect of those conditions on the United States’ legal obligations.

Drawing on a database of almost 400 multilateral treaties to which the United States is a party, this article demonstrates that the U.S. Senate’s use of such conditions has grown significantly over the last few decades, particularly with respect to the use of conditions other than reservations. The Senate purports to use conditions to modify the United States’ legal obligations; to clarify ambiguous treaty terms; and to address how a treaty is to be implemented in U.S. law. However, the legal effect of the Senate’s use of conditions, both in U.S. law and international law, is often murky. Accordingly, this article examines Senate practice with respect to its advice and consent function for multilateral treaties to determine what is happening in this area of the law and whether changes should be made.

The article explains the legal authority for the use of conditions in U.S. treaty practice, and describes different types of conditions the Senate has used, how and when the Senate adds conditions to such agreements, and how Senate practice has changed over time. The article identifies the types of conditions most frequently added by the Senate and examines whether conditions are more likely depending on the treaty’s subject matter. Based on this observed behavior, the article proposes some theories as to why the U.S. Senate is more likely to add conditions to certain types of treaties than others. The article also considers whether a prohibition on treaty reservations significantly lessens the likelihood the United States will join.

Next, the article analyzes the consistency of U.S. treaty practice with international practice. This examination shows that U.S. treaty practice is not entirely consistent with international practice, especially with respect to the use of “understandings.” It also highlights legal problems that may arise through the use of conditions. The article then discusses the extent to which the other branches of U.S. government are or should be bound by the different types of conditions proposed by the Senate. Finally, the article concludes with some recommendations regarding changes in treaty practice for the future.

  • Treaties,
  • conditions,
  • reservations,
  • international,
  • law,
  • empirical
Publication Date
July 21, 2015
Citation Information
Cindy G. Buys. "Conditions in U.S. Treaty Practice: New Data and Insights into a Growing Phenomenon" ExpressO (2015)
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