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. Unlike the process of terminating executive agreements, which has not generated extensive opposition from Congress, the constitutional requirements for the termination of Senate-approved, ratified treaties have been the subject of occasional debate between the legislative and executive branches. The Constitution sets forth a definite procedure for the President to make treaties with the advice and consent of the Senate, but it does not describe how they should be terminated. Some commentators and executive branch attorneys have argued that the President possesses broad powers to withdraw unilaterally from treaties based on Supreme Court case law describing the President as the "sole organ" of the nation in matters related to foreign affairs and pursuant to the "executive Power" conveyed to the President in Article II, Section 1 of the Constitution . Other proponents of executive authority have likened the power to withdraw from treaties to the President's power to remove executive officers . Although appointment of certain executive officers requires senatorial advice and consent, courts have held that the President has some unilateral authority to remove those officers. In the same vein, some argue that the President may unilaterally terminate treaties even though those treaties were formed with the consent of the Senate. Since the turn of the 20 th century, officials in the executive branch have adopted variations of these arguments and consistently taken the position that domestic law permits the President to terminate or withdraw from treaties without receiving express approval from the legislative branch . Not all courts and commentators, however, agree that the President possesses this power, or at least contend that the power is shared between the political branches and that the President cannot terminate a treaty in contravention of the will of Congress or the Senate. Some have argued that the termination of treaties is analogous to the termination of federal statutes. Because domestic statutes may be terminated only through the same process in which they were enacted —i.e., through a majority vote in both houses and with the signature of the President or veto override—these commentators contend that treaties must be terminated through a procedure that is symmetrical to their making and that includes, at a minimum, the Senate's consent. Proponents of congressional or senatorial participation further assert the Founders could not have intended the President to be the "sole organ" in the broader context of treaty powers because the Treaty Clause expressly provides a role for the Senate in the formation of treaties. While proponents on both sides of the debate over the Executive's power of unilateral treaty termination cite historical practices in favor of their respective branches, past practices related to treaty termination vary considerably. These historical practices can generally be organized into five categories: 1. executive withdrawal or termination pursuant to prior authorization or direction from Congress; 2. executive withdrawal or termination pursuant to prior authorization or direction from the Senate; 3. executive withdrawal or termination without prior authorization, but with subsequent approval by Congress; 4. executive withdrawal or termination without prior authorization, but with subsequent approval by the Senate; and 5. unilateral executive withdrawal or termination without authorization or direction by Congress or the Senate. During the 19th century, treaties consistently were terminated through one of the first four methods listed above, all of which include joint action by the legislative and executive branches. At the turn of the 20th century, however, historical practices began to change, and the fifth form of treaty termination emerged: unilateral termination by the President without approval by the legislative branch. During the Franklin Roosevelt Administration and World War II, unilateral presidential termination increased markedly. Although Congress occasionally enacted legislation authorizing or instructing the President to terminate treaties during the 20th century, unilateral presidential termination eventually became the norm. In most cases, this presidential action has not generated significant opposition in either chamber of Congress, but there have been occasions in which Members filed suit in an effort to block the President from terminating a treaty without first receiving congressional or senatorial approval. The most prominent attempt by Members of Congress to prevent the President from terminating a treaty through litigation occurred during the 1970s as the United States began to pursue closer relations with the government of the People's Republic of China (PRC). Anticipating that, as part of its efforts to normalize relations with the PRC, the executive branch might terminate a 1954 mutual defense treaty with the government of Taiwan, Congress enacted (and President Carter signed) the International Security Assistance Act, which, among other things, expressed "the sense of the Congress that there should be prior consultation between the Congress and the executive branch on any proposed policy changes affecting the continuation in force of the Mutual Defense Treaty of 1954." When the Carter Administration announced that the United States would provide the required notice to terminate the treaty without having first obtained the consent of Congress, a group of 16 Members of the House of Representatives and 9 Senators, led by Senator Barry Goldwater, filed suit before the U.S. District Court for the District of Columbia seeking to block the President's action on the ground that the Executive lacks the constitutional authority for unilateral treaty termination. In the early stages of the litigation, the district court agreed with the Members and entered an order permanently enjoining the State Department from "taking any action to implement the President's notice of termination unless and until that notice is so approved [by the Senate or Congress]." The district court reasoned as follows: [T]reaty termination generally is a shared power, which cannot be exercised by the President acting alone. Neither the executive nor legislative branch has exclusive power to terminate treaties. At least under the circumstances of this case involving a significant mutual defense treaty . . . any decision of the United States to terminate that treaty must be made with the advice and consent of the Senate or the approval of both houses of Congress. Notably, the district court relied, in part, on historical practice, and stated that, although no definitive procedure exists, "the predominate United States' practice in terminating treaties . . . has involved mutual action by the executive and legislative branches." On appeal, the U.S. Court of Appeals for the District of Columbia Circuit (D.C. Circuit), sitting en banc, disagreed both with the district court's interpretation of past practice and the ultimate decision on the constitutionality of President Carter's action. In addition to relying on case law emphasizing the President's role as the "sole organ" in foreign relations, the D.C. Circuit reasoned that past practices were varied, and that there was no instance in which a treaty continued in force over the opposition of the President. Of "central significance" to the appellate court's decision was the fact that the Mutual Defense Treaty of 1954 contained a termination clause. Because there was "[n]o specific restriction or condition" on withdrawal specified in the termination clause, and because the Constitution does not expressly forbid the Executive from terminating treaties, the D.C. Circuit reasoned that the termination power, for that particular treaty, "devolves upon the President[.]" In an expedited decision issued two weeks later, the Supreme Court vacated the appellate court's decision and remanded with instructions to dismiss the complaint, but it did so without reaching the merits of the constitutional question and with no majority opinion. Writing for a four-Justice plurality, Justice Rehnquist concluded that the case should be dismissed because it presented a nonjusticiable political question—meaning that the dispute was more properly resolved in the politically accountable legislative and executive branches than in the court system. One member of the Court, Justice Powell, also voted for dismissal, but did so based on the ground that the case was not ripe for judicial review until the Senate passed a resolution disapproving of the President's termination. Only one Justice reached a decision on the constitutionality of President Carter's action: Justice Brennan would have affirmed the D.C. Circuit, but his opinion was premised on the conclusion that termination of the Mutual Defense Treaty implicated the Executive's power to recognize the PRC as the official government of China, and not because the President possesses a general, constitutional power over treaty termination. Accordingly, it is not clear that Justice Brennan's reasoning would apply to all treaties, particularly those that do not address matters where the President does not have preeminent constitutional authority. In the years after the litigation over the Mutual Defense Treaty with Taiwan, the Executive continued the practice of unilateral treaty termination in many, but not all, cases. In 1986, a group of private plaintiffs filed suit seeking to prevent President Reagan from unilaterally terminating a Treaty of Friendship, Commerce, and Navigation with Nicaragua, but the district court dismissed the suit as a nonjusticiable political question following the reasoning of the four-Justice plurality in Goldwater . Sixteen years later, Members of Congress again instituted litigation in opposition to the President's unilateral termination, this time in response to George W. Bush's 2001 announcement that he was terminating the Anti-Ballistic Missile (ABM) Treaty with Russia. Thirty-two Members of the House of Representatives challenged the constitutionality of that termination in Kucinich v. Bush , but the district court dismissed the suit on jurisdictional grounds without reaching the merits for two reasons. First, the court held that the Member-Plaintiffs failed to meet the standards for Members of Congress to have standing to assert claims for institutional injuries to the legislative branch as set by the Supreme Court in Raines v. Byrd . Second, the district court held that the interbranch dispute over the proper procedure for treaty termination was a nonjusticiable political question better resolved in the political branches. The district court did not opine on the underlying constitutional question, and no appeal was filed. In addition to courts' reluctance to reach the merits of separation of powers disputes over treaty termination, past cases have not addressed a circumstance in which the Executive's decision to terminate a treaty was in direct opposition to the stated will of the Senate or Congress. While the International Security Assistance Act, passed in 1978, expressed the sense of the Congress that there should be consultation between the Congress and the executive branch related to termination of the Mutual Defense Treaty with Taiwan, it did not direct the President to obtain the Senate's consent before terminating the treaty. The following year, the Senate introduced a resolution expressing the "sense of the Senate that approval of the United States Senate is required to terminate any mutual defense treaty between the United States and another nation." But that resolution was never passed, and it does not appear that Congress has enacted a provision purporting to block the President from terminating a treaty or expressing the sense of the Senate or Congress that unilateral termination by the President is wrongful unless approved by Congress. If such an act or resolution were passed and the Executive still terminated without approval from the legislative branch, the legal paradigm governing the separation of powers analysis might shift. When faced with certain separation of powers conflicts, the Supreme Court has frequently adopted the reasoning of Justice Jackson's oft-cited concurring opinion in Youngstown Sheet & Tube Co. v. Sawyer , which stated that the President's constitutional powers often "are not fixed but fluctuate, depending on their disjunction or conjunction with those of Congress." Justice Jackson's opinion sets forth a tripartite framework for evaluating the constitutional powers of the President. The President's authority is (1) at a maximum when acting pursuant to authorization by Congress; (2) in a "zone of twilight" when Congress and the President "may have concurrent authority, or in which its distribution is uncertain," and Congress has not spoken on an issue; and (3) at its "lowest ebb" when taking measures incompatible with the will of Congress. Because Congress, in Goldwater and the district court cases discussed above, had not passed legislation disapproving the President's terminations, presidential authority in those cases likely fell into the "zone of twilight." But a future resolution or legislation disapproving of unilateral treaty termination could place the President's authority at the "lowest ebb." In that scenario, the President only may act in contravention of the will of Congress in matters involving exclusive presidential prerogatives that are "at once so conclusive and preclusive" that they "disabl[e] the Congress from acting upon the subject." Members of the executive branch have suggested that treaty termination is part of the President's plenary powers, but a counterargument could be made that the legislative branch plays a shared role in the termination process, especially in matters that implicate Congress's enumerated powers. The legal framework for withdrawal from an international agreement may also depend on whether Congress has enacted legislation implementing its provisions into the domestic law of the United States. Some provisions of international agreements are considered self-executing and have the force of domestic law without the need for subsequent congressional action. But for non-self-executing provisions or agreements, implementing legislation from Congress may be required to provide U.S. agencies with legal authority to carry out functions contemplated by the agreement or to make them enforceable by private parties. Certain political commitments have also been incorporated into domestic law through implementing legislation. Under Supreme Court precedent, the repealing of statutes generally must conform to the same bicameral process set forth in Article I that is used to enact new legislation. Accordingly, when Congress has passed legislation implementing an international pact into domestic law, the President would appear to lack the authority to terminate the domestic effect of that legislation without going through the full legislative process for repeal. Even when the President may have the power under international law to withdraw the United States from an international pact and suspend U.S. obligations to its pact counterparts, that withdrawal likely would not, on its own accord, repeal the domestic effect of implementing legislation. Moreover, Congress could influence the international pact's role in domestic law by repealing the pact's implementing legislation, and such a repeal could encourage the President to withdraw from the pact. In some cases, implementing legislation may dictate the extent to which termination of an underlying international agreement affects domestic law. For example, implementing legislation for several bilateral trade agreements provides that, on the date the agreement terminates, the provisions of the implementing legislation automatically cease to be effective immediately. In other cases, legislation expressly delays the impact that termination of an international agreement would have on domestic law. Consequently, analysis of the terms of the implementing statutes may be necessary to understand the precise legal effect that termination of an international agreement has on U.S. law. On June 1, 2017, President Trump announced that he intends to withdraw the United States from the Paris Agreement—a multilateral, international agreement intended to reduce the effects of climate change by maintaining global temperatures "well below 2°C above pre-industrial levels[.]" The Paris Agreement is a subsidiary to the 1992 United Nations Framework Convention on Climate Change (UNFCCC), a broader, framework treaty entered into during the George H. W. Bush Administration. Unlike the UNFCCC, which received the Senate's advice and consent in 1992, the Paris Agreement was not submitted to the Senate for approval. Instead, the Obama Administration took the position that the Paris Agreement is an executive agreement for which senatorial or congressional approval was not required. President Obama signed an instrument of acceptance of the Paris Agreement on August 29, 2016, which was deposited with U.N. Secretary General Ban-Ki Moon on September 3, 2016. The Agreement entered into force on November 4, 2016. Although the Obama Administration described the Paris Agreement as an executive agreement, it did not publicly articulate the precise sources of executive authority on which the President relied in entering into the Agreement. Possible sources include the UNFCCC, existing statutes such as the Clean Air Act and Energy Policy Act, the President's sole constitutional powers, or a combination of these authorities. While the precise source of authority is not readily apparent, there does not appear to be an underlying restriction on unilateral presidential withdrawal (i.e., a treaty reservation, statutory restriction, or other form of limitation) in any of the potential sources of executive authority. Therefore, the Paris Agreement would likely fall into the category of executive agreements that the Executive has terminated without seeking consent from the Senate or Congress. Although the President's domestic withdrawal has not been disputed, the terms of the Paris Agreement establish a multiyear withdrawal process that appears to prevent nations from immediately exiting the Agreement. Article 28.1 specifies the procedure for withdrawal, stating: "any time after three years from the date on which this Agreement has entered into force . . ., [a] Party may withdraw from this Agreement by giving written notification" to the Secretary-General of the United Nations. Further, under Article 28.2 , a notice of withdrawal does not become effective until one year after the Secretary-General receives written notification. Because the Paris Agreement did not enter into force until November 4, 2016 , the United States could not fully withdraw under the Article 28 procedure until November 4, 2020. President Trump did not mention Article 28 during his June 1, 2017 announcement, and some of the President's statements could be interpreted to suggest that the Trump Administration considered the withdrawal announcement to have terminated the United States' participation in Agreement immediately. However, subsequent actions by the Trump Administration officials have clarified that, although the United States intends to exercise its right to withdrawal from the Agreement "as soon as it is eligible to do so[,]" it will comply with the requirements of Article 28. Some commentators advocated for withdrawal from the parent treaty to the Paris Agreement—the UNFCCC—as a more expedient method of exiting the Paris Agreement. Article 28 of the Paris Agreement provides that any party that withdraws from the UNFCCC shall be considered also to have withdrawn from the Paris Agreement. The UNFCCC has nearly identical withdrawal requirements to the Paris Agreement, but because the UNFCCC entered into force in 1994, the three-year withdrawal prohibition expired in 1997. Therefore withdrawal from both the parent treaty and the subsidiary Paris Agreement could be accomplished within one year. The Trump Administration, however, has not announced that it intends to take action with respect to the UNFCCC. Therefore, at present, the United States remains a party to the subsidiary Paris Agreement until Article 28's withdrawal procedure is complete—albeit one that has announced its intention to withdraw once it is eligible to do so. On October 13, 2017, President Trump delivered a speech in which he described his Administration's strategy toward Iran and criticized the Joint Comprehensive Plan of Action (JCPOA) related to Iran's nuclear program that was entered into during the Obama Administration. The JCPOA was finalized in 2015 when Iran and six nations (the United States, the United Kingdom, France, Russia, China, and Germany—collectively known as the P5+1) finalized the "plan of action" placing limitations on the development of Iran's nuclear program . The JCPOA identifies a series of "voluntary measures" in which the P5+1 provides relief from sanctions imposed on Iran through U.S. law, EU law, and U.N. Security Council resolutions in exchange for Iranian implementation of certain nuclear-related measures. In his October 2017 speech, the President announced that he would not renew certain certifications related to Iranian compliance with the JCPOA established under Iran Nuclear Agreement Review Act, and the President again declined to certify compliance in January 12, 2018. The certification provisions in the Iran Nuclear Agreement Review Act are related to, but separate from, the commitments made by Iran and the P5+1 in the JCPOA. As discussed in more detail below, the President's certification decisions did not automatically terminate the United States' participation in the JCPOA or re-impose lifted sanctions, even though the President stated that he may take these actions in the future and may have domestic legal authority to do so unilaterally. The JCPOA was not signed by any party, and it does not contain provisions for ratification or entry into force, but the bulk of the sanctions addressed by the document were lifted on January 16, 2016, the date referred to as "Implementation Day." Because the JCPOA is an unsigned document that purports to rely on "voluntary measures" rather than binding obligations, the Obama Administration treated the document as a political commitment that did not require congressional or senatorial approval. Many commentators agree with this assessment, but there is some debate over the classification of the plan of action, and its legal status may have been affected by a subsequent U.N. Security Council resolution (discussed below). To the extent the JCPOA is correctly understood as a nonbinding political commitment, international law would not prohibit President Trump from withdrawing from the plan of action and reinstating certain sanctions that had been previously imposed under U.S. law, but there may be political consequences for this course of action. It is also unlikely that domestic law would require congressional or senatorial approval for withdrawal in light of the Obama Administration's treatment of the JCPOA as a nonbinding commitment. The JCPOA states that the United States will, among other things, withdraw certain "secondary sanctions" imposed under U.S. law that are related to foreign entities and countries that conduct specified transactions with Iran. "Secondary" sanctions are distinguished from "primary" sanctions in that primary sanctions prohibit economic activity with Iran involving U.S. persons or goods, and secondary sanctions seek to discourage non-U.S. parties from doing business with Iran. On Implementation Day, President Obama issued an executive order revoking all or portions of five prior executive orders that imposed secondary sanctions on Iran. These executive orders generally may be revoked or modified at the will of the President, and therefore nothing in domestic law would prevent President Trump from reinstating these sanctions through his own executive order, provided he complies with the requirements of the underlying statutes that authorize the President to sanction Iran via executive order. Other secondary sanctions addressed in the JCPOA were imposed on Iran by statute rather than through executive order. These statutes gave the President or a delegate in the executive branch authority to waive sanctions under certain conditions, and the waiver remains effective for a period ranging from 120 days to one year, depending on the statute. The Obama Administration first exercised this waiver authority on Implementation Day, and the Trump Administration has continued to issue these waivers, most recently on July 17, 2017 and January 12, 2018. When those waivers expire, nothing in domestic law would prevent the Trump Administration from choosing not to renew them, thereby reinstating U.S. sanctions imposed on Iran by statute. In addition to U.S. withdrawal of secondary sanctions, the JCPOA calls for the "comprehensive lifting of all U.N. Security Council sanctions . . . related to Iran's nuclear programme," and it specifies a set of resolutions to be terminated through a future act of the Security Council. On July 20, 2015, the Security Council unanimously voted to approve Resolution 2231, which, as of Implementation Day, terminated the prior sanctions-imposing Security Council resolutions subject to certain terms in Resolution 2231 and the JCPOA. Resolution 2231 annexes the JCPOA, and it states that the Security Council "[w]elcom[es] diplomatic efforts by [the P5+1] and Iran to reach a comprehensive, long-term and proper solution to the Iranian nuclear issue, culminating in the [JCPOA]." Although the text of the JCPOA appears to rely on "voluntary measures," some observers have stated that Resolution 2231 may have converted some voluntary political commitments in the JCPOA into legal obligations that are binding under U.N. Charter. Whether a U.N. Security Council resolution imposes legal obligations on U.N. Member States depends on the nature of the provisions in the resolution. As a matter of international law, many observers agree that "decisions" of the Security Council are generally binding pursuant to Article 25 of the U.N. Charter, but the Security Council's "recommendations," in most cases, lack binding force. Whether a provision is understood as a nonbinding "recommendation" or a binding "decision" frequently depends on the precise language in the resolution. Commentators have noted that the Security Council's use of certain affirmative language, such as "shall" as opposed to "should," or "demand" as opposed to "recommend," may indicate that a resolution is intended to establish legally binding duties upon U.N. Member States. Resolution 2231 appears to contain a combination of nonbinding recommendations and binding decisions. It seems clear that the Security Council intended the provisions that lifted its prior sanctions to be binding, as these paragraphs begin with the statement that the Security Council " Decide s , acting under Article 41 of the Charter of the United Nations" that its prior resolutions are terminated subject to certain conditions. Article 41 authorizes the Security Council to "decide" what measures "not involving the use of armed force are to be employed to give effect to its decisions," and it is understood to allow the Security Council to issue resolutions that are binding on U.N. Member States. Whether Resolution 2231 creates an obligation under international law for the United States to continue to withhold its domestic secondary sanctions or to comply with the JCPOA more broadly is a more complex question. Paragraph 2 of Resolution 2231 states that the Security Council: Calls upon all Members States . . . to take such actions as may be appropriate to support the implementation of the JCPOA, including by taking actions commensurate with the implementation plan set out in the JCPOA and this resolution and by refraining from actions that undermine implementation of commitments under the JCPOA[.] While this provision arguably seeks general compliance with the JCPOA, the phrase "calls upon" is understood by some commentators as a hortatory, nonbinding expression in Security Council parlance. Others have interpreted the phrase to create an obligation under international law to comply, and a third group falls in between, describing the phrase as purposefully ambiguous. Historically, U.N. Member States have ascribed varying levels of significance to the phrase "calls upon" in Security Council resolutions. As a consequence, there may not be a definitive answer as to whether Resolution 2231 creates a binding international legal obligation for the United States to "support the implementation of the JCPOA" or whether the JCPOA remains a nonbinding political commitment that the United States may withdraw from without violating international law. As a matter of domestic law, U.N. Security Council Resolutions are frequently seen to be non-self-executing, and therefore their legal effect is dependent on their relationship with existing authorizing or implementing legislation. In certain cases, existing statutory enactments may authorize the Executive to implement the provisions of a resolution through economic and communication-related sanctions. But, to the extent Resolution 2231 is not self-executing, domestic law would not, on its own accord, mandate that the President comply with the terms of the resolution. Because the Obama Administration treated the JCPOA as a nonbinding political commitment for which congressional or senatorial consent was not required, Congress did not directly approve the United States' entry into the JCPOA. However, Congress did pass legislation—the Iran Nuclear Agreement Review Act —providing certain congressional review and oversight over the plan of action. Among other provisions, the Iran Nuclear Agreement Review Act requires the President to certify every 90 days that Iran (i) is fully implementing the JCPOA; (ii) has not committed an uncured, material breach of the plan of action; (iii) has not taken action that could significantly advance its nuclear weapons program; and (iv) that the continued suspension of sanctions under the JCPOA is vital to the national security interests of the United States and is "appropriate and proportionate" to Iran's measures to terminate its nuclear weapons program. If the President elects not to certify, the Act allows Congress to use expedited procedures to pass legislation re-imposing U.S. sanctions that the President lifted pursuant to the JCPOA. In his October 13 announcement, President Trump stated that he is withholding certification under the Iran Nuclear Agreement Review Act on the ground that he cannot certify that the continued lifting of sanctions is "appropriate and proportionate" relative to Iran's measures to terminate its nuclear weapons program. The President did not state that he is immediately terminating U.S. participation in the JCPOA or re-imposing U.S. domestic sanctions under his own authority. Rather, declining to certify Iranian compliance provides Congress with an opportunity to utilize the Iran Nuclear Agreement Review Act's expedited procedures to re-impose sanctions on Iran. Still, the President stated that he had the authority to terminate the JCPOA "at any time." And in a January 2018 speech on the JCPOA, President Trump stated that "the United States will not again waive sanctions in order to stay in the Iran nuclear deal[,]" and that he "will withdraw from the deal immediately" unless the JCPOA is renegotiated." For the reasons described in the sections above, under current domestic law, the President may possess authority to terminate U.S. participation in the JCPOA and to re-impose U.S. sanctions on Iran, either through executive order or by declining to renew statutory waivers. As a matter of international law, by contrast, termination of the JCPOA or re-imposition of sanctions (either by Congress or the President alone) could implicate the question of whether Resolution 2231 converted the JCPOA's nonbinding political commitments into obligations that are binding under the U.N. Charter. Absent an uncured breach or nonperformance of the JCPOA by Iran, which the Trump Administration has not claimed to date, some argue that unilateral withdrawal from the plan of action or re-imposition of U.S. secondary sanctions would amount to a violation of Resolution 2231. But there is no clear answer on whether this Security Council resolution creates a legally binding obligation to comply with the overall terms of the JCPOA, and the political ramifications of any future U.S. action related to JCPOA may be significant regardless of which legal interpretation is superior. If the Trump Administration believes Iran has not complied with the JCPOA, the terms of the plan of action and Resolution 2231 may offer an avenue for the United States to relieve itself of any commitments under the JCPOA regardless of whether those commitments were converted to legally binding obligations. Article 36 of the JCPOA establishes a multistage dispute resolution procedure that can be invoked if the United States (or another member of the P5+1) believes Iran is "not meeting its commitments" under the plan of action. If the dispute remains unresolved after this process, Article 36 would allow the United States to cease performing its commitments, provided it deems Iran's actions to constitute "significant nonperformance" of the JCPOA. "Significant non-performance" is not defined in the JCPOA or Resolution 2231, but a party may report such nonperformance to the U.N. Security Council. After receiving a notice of nonperformance, Resolution 2231 requires the Security Council to vote on a draft resolution addressing whether it should continue to withhold the U.N. sanctions imposed on Iran through its earlier resolutions. Unless the Security Council votes to continue to lift those sanctions within 30 days of receiving a notice of significant nonperformance, the prior Security Council resolutions "shall apply in the same manner as they applied before the adoption of" Resolution 2231. Thus, the Resolution 2231 creates a procedure—often referred to as the "snapback" process —that places the onus on the Security Council to vote affirmatively to continue to lift its sanctions. As a permanent member of the Security Council, the United States would possess the power to veto any such vote and effectively force the reinstatement of the Security Council's sanctions on Iran. To date, President Trump has criticized Iran's performance of the JCPOA, but the Administration does not appear to have publicly invoked the dispute resolution mechanisms or the "snapback" process. 

Summary: The legal procedure through which the United States withdraws from treaties and other international agreements has been the subject of long-standing debate between the legislative and executive branches. Recently, questions concerning the role of Congress in the withdrawal process have arisen in response to President Donald J. Trump's actions related to certain high-profile international commitments. This report outlines the legal framework for withdrawal from international agreements under domestic and international law, and it applies that framework to two pacts that may be of significance to the 115th 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 Executive 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 agreements between the United States and foreign nations take the form of Senate-approved, ratified treaties. The President also enters into executive agreements, which do not receive the Senate's advice and consent, and "political commitments" that are not binding under domestic or international law. The legal procedure for withdrawal often depends on the type of agreement at issue, and the process may be further complicated when Congress has enacted legislation to give the international agreement domestic legal effect. On June 1, 2017, President Trump announced that he intends to withdraw the United States from the Paris Agreement—a multilateral, international agreement intended to reduce the effects of climate change. Historical practice suggests that, because the Obama Administration considered the Paris Agreement to be an executive agreement that did not require the Senate's advice and consent, the President potentially may claim authority to withdraw without seeking approval from the legislative branch. By its terms, however, the Paris Agreement does not allow parties to complete the withdrawal process until November 2020, and Trump Administration officials have stated that the Administration intends to follow the multiyear withdrawal procedure. Consequently, absent additional action by the Trump Administration, the United States will remain a party to the Paris Agreement until November 2020, albeit one that has announced its intent to withdraw once it is eligible to do so. The Trump Administration has not withdrawn the United States from the JCPOA, but the President has stated he intends do so unless the plan of action is renegotiated. When the Obama Administration concluded the JCPOA, it treated the plan of action as a non-binding political commitment. To the extent this understanding is correct, President Trump's ability to withdraw from the JCPOA would not be restricted by international or domestic law. However, some observers have suggested that U.N. Security Council Resolution 2231 subsequently converted at least some provisions in the JCPOA into obligations that are binding under international law. As a result, withdrawal from the JCPOA could implicate a complex debate over the plan of action's status in international law. As a matter of domestic law, the President and Congress have authority to reassert sanctions lifted pursuant to U.S. pledges made in the JCPOA if they deem the reinstitution of such sanctions to be appropriate, even if such action resulted in a violation of international law. Several possible domestic legal avenues exist to re-impose sanctions, some of which would involve joint action by the President and the legislative branch, and others that would involve decisions made by the President alone.