Essentials of treaty law
In domestic U.S. law there are important distinctions between treaties and executive agreements. This distinction primarily involves issues of constitutional authority within the U.S. government, but it is of little importance internationally. Treaties and executive agreements are equally binding between the United States and the other party or parties to an international agreement.
Treaty obligations are binding on their parties, but international law recognizes certain circumstances in which a nation can regard a treaty obligation as being suspended, modified, or terminated. The parties can always modify or terminate a treaty by mutual consent. Some international agreements expire by their own terms after a fixed period of time. Generally, unless the terms of the agreement establish a right of unilateral withdrawal, a nation may not unilaterally repudiate or withdraw from a treaty unless it has a basis for doing so that is recognized under international law.
Treaty obligations are reciprocal in nature. If one of the parties commits a material breach of its obligations under the treaty, the other may be entitled to suspend its own compliance, or to withdraw from the agreement entirely. Also, a fundamental change in circumstances may justify a decision by one of the parties to regard its treaty obligations as suspended or terminated. One of these fundamental changes of circumstance is the initiation of armed hostilities between the parties. Some international agreements specifically provide that they will remain in effect during armed conflict between the parties, such as law of war treaties and the United Nations Charter.
Most treaties, however, are silent on whether or not they will continue to apply during hostilities between the parties. Many peacetime agreements facilitate tourism, transportation, commerce, and other relationships the continuation of which would be fundamentally inconsistent with a state of armed conflict between the parties. Agreements on other subjects, such as boundary settlements and reciprocal rights of inheritance of private property, may be unrelated to the existence of hostilities, and may ultimately be determined to remain in full force.
The issues involved may be particularly complicated when the treaty concerned is multilateral, rather than bilateral. When two parties to a multilateral treaty are engaged in armed conflict, the result may well be that the effect of the treaty is suspended between the belligerents, but remains in effect among each belligerent and the other parties. The tests to apply are (1) whether there is specific language in the treaty addressing its effect during hostilities between the parties, and (2) if there is no such language, whether the object and purpose of the treaty is or is not compatible with a state of armed hostilities between the parties.
- This article uses the term "treaty" as a shorthand way of referring to all forms of legally binding state-to-state international agreements.