Renewed attention to the role of Congress in the termination of treaties and other international agreements has arisen in response to President Donald J. Trump's actions related to certain high-profile international commitments. This report examines the legal framework for withdrawal from international agreements, and it focuses specifically on two pacts that may be of interest to the 115 th Congress: the Paris Agreement on climate change and the Joint Comprehensive Plan of Action (JCPOA) related to Iran's nuclear program. Although the Constitution sets forth a definite procedure whereby the President has the power to make treaties with the advice and consent of the Senate, it is silent as to how treaties may be terminated. Moreover, not all pacts between the United States and foreign nations take the form of Senate-approved, ratified treaties. The President commonly enters into binding executive agreements, which do not receive the Senate's advice and consent, and "political commitments," which are not legally binding, but may carry significant political weight . Executive agreements and political commitments are not mentioned in the Constitution, and the legal procedure for withdrawal may differ depending on the precise nature of the pact. Treaties and other international pacts also operate in dual international and domestic contexts. In the international context, many international agreements that are binding in nature constitute compacts between nations, and they often create rights and obligations that sovereign states owe to one another under international law. In this regard, international law creates a distinct set of rules governing the way in which sovereign states enter into—and withdraw from—international agreements. Those procedures are intended to apply to all nations, but they may not account for the distinct constitutional and statutory requirements of the domestic law of the United States. Consequently, the legal regime governing withdrawal under domestic law may differ in meaningful ways from the procedure for withdrawal under international law. And the domestic withdrawal process may be further complicated if Congress has enacted legislation implementing an international pact into the domestic law of the United States. In sum, the legal procedure for termination of or withdrawal from treaties and other international pacts depends on three main features: (1) the type of pact at issue; (2) whether withdrawal is analyzed under international law or domestic law; and (3) whether Congress has enacted implementing legislation. These procedures and considerations are explored below and applied to the Paris Agreement and the JCPOA. For purposes of U.S. law and practice, pacts between the United States and foreign nations may take the form of treaties, executive agreements, or nonlegal agreements, which involve the making of so-called "political commitments." Under the domestic law of the United States, a treaty is an agreement between the United States and another state that does not enter into force until it receives the advice and consent of a two-thirds majority of the Senate and is subsequently ratified by the President. The great majority of international agreements that the United States enters into, however, fall into the distinct and much larger category of executive agreements. Although they are intended to be binding, executive agreements do not receive the advice and consent of the Senate, but rather are entered into by the President based upon a source of authority other than the Treaty Clause in Article II, Section 2 of the Constitution. In the case of congressional-executive agreements , the domestic authority is derived from an existing or subsequently enacted statute. The President also enters into executive agreements made pursuant to a treaty based upon authority created in prior Senate-approved, ratified treaties. In other cases, the President enters into sole executive agreements based upon a claim of independent presidential power in the Constitution. In addition to treaties and executive agreements, the United States makes nonlegal pacts that often involve the making of so-called political commitments . While political commitments are not intended to be binding under domestic or international law, they may nonetheless carry moral and political weight and other significant incentives for compliance. Under international law, a nation may withdraw from any binding international agreement either in conformity with the provisions of the agreement—if the agreement permits withdrawal—or with the consent of all parties. Most modern international agreements contain provisions allowing and specifying the conditions of withdrawal, and many require a period of advance notice before withdrawal becomes effective . Even when an agreement does not contain an express withdrawal clause, international law still permits withdrawal if the parties intended to allow a right of withdrawal or if there is an implied right to do so in the text of the agreement. In those cases, under the Vienna Convention on the Law of Treaties (Vienna Convention), the withdrawing party must give 12 months' notice of its intent to depart from the agreement. In addition, certain superseding events, such as a material breach by one party or a fundamental change in circumstances, may give rise to a right to withdraw. Under the Vienna Convention, treaties and other binding international agreements may be terminated through: [a]ny act declaring invalid, terminating, withdrawing from or suspending the operation of a treaty pursuant to the provisions of the treaty . . . through an instrument communicated to the other parties. If the instrument is not signed by the Head of State, Head of Government or Minister for Foreign Affairs, the representative of the State communicating it may be called upon to produce full powers. Under this rule, a notice of withdrawal issued by the President (i.e., the "Head of State" for the United States) would effectively withdraw the United States from the international agreement as a matter of international law, provided such notice complied with applicable treaty withdrawal provisions. In this regard, the withdrawal process under international law may not account for the unique constitutional and separation of powers principles related to withdrawal under U.S. domestic law, discussed below. Political commitments are not legally binding between nations, and thus a party can withdraw at any time without violating international law regardless of whether the commitment contains a withdrawal clause. Although such withdrawal may not constitute a legal infraction, the withdrawing party still may face the possibility of political consequences and responsive actions from its international counterparts. Under domestic law, it is generally accepted among scholars that the Executive, by virtue of its role as the "sole organ" of the government charged with making official communications with foreign states, is responsible for communicating the United States' intention to withdraw from international agreements and political commitments. The degree to which the Constitution requires Congress or the Senate to participate in the decision to withdraw, however, has been the source of historical debate and may differ depending on the type of pact at issue. And in those cases when the President's authority to terminate an international pact has been challenged in court, discussed below, courts have declined to answer the underlying separation-of-powers question. Instead, the executive and legislative branches largely have been left to resolve disagreement over the termination power through political processes rather than through judicial settlement. In the case of executive agreements, it appears to be generally accepted that, when the President has independent authority to enter into an executive agreement, the President may also independently terminate the agreement without congressional or senatorial approval. Thus, observers appear to agree that, when the Constitution affords the President authority to enter into sole executive agreements, the President also may unilaterally terminate those agreements. This same principle would apply to political commitments: to the extent the President has the authority to make nonbinding commitments without the assent of the Senate or Congress, the President also may withdraw unilaterally from those commitments. For congressional-executive agreements and executive agreements made pursuant to treaties, the mode of termination may be dictated by the underlying treaty or statute on which the agreement is based. For example, in the case of executive agreements made pursuant to a treaty, the Senate may condition its consent to the underlying treaty on a requirement that the President not enter into or terminate executive agreements under the authority of the treaty without senatorial or congressional approval. And for congressional-executive agreements, Congress may dictate how termination occurs in the statute authorizing or implementing the agreement. Congress also has asserted the authority to direct the President to terminate congressional-executive agreements. For example, in the Comprehensive Anti-Apartheid Act of 1986, which was passed over President Reagan's veto, Congress instructed the Secretary of State to terminate an air services agreement with South Africa. The Reagan Administration complied and provided the requisite notice of termination. Another example of Congress asserting a role in the termination of congressional-executive agreements was via the Trade Agreements Extension Act of 1951. The Act directed the President to "take such action as is necessary to suspend, withdraw or prevent the application of" trade concessions contained in prior trade agreements regulating imports from the Soviet Union and "any nation or area dominated or controlled by the foreign government or foreign organization controlling the world Communist movement." The Truman Administration relied on this law in terminating certain congressional-executive agreements with the Soviet Union and several Soviet satellite countries. Presidents also have asserted the authority to withdraw unilaterally from congressional-executive agreements, but there is an emerging scholarly debate over the extent to which the Constitution permits the President to act without the approval of the legislative branch in such circumstances. For congressional-executive agreements that Congress pre-authorized by statute (called ex ante agreements), Presidents sometimes have unilaterally terminated the agreement without objection. But for those congressional-executive agreements that are approved by Congress after they are entered into by the President (called ex post agreements), commentators disagree on whether the President possesses the power of unilateral termination. Some argue that certain congressional-executive agreements—chiefly those involving international trade —are based on exclusive congressional powers, and therefore Congress must approve their termination. Others assert that the President has the power to withdraw from these agreements unilaterally, but he cannot terminate the domestic effect of their implementing legislation in the absence of congressional authorization —an issue discussed in more detail below. Although this debate is still developing, unilateral termination of congressional-executive agreements by the President has not been the subject of a high volume of litigation, and prior studies have concluded that such termination has not generated large-scale opposition from the legislative branch.