One Voice for the Nation: Unitary Executive Theory and Its Limitations in International Relations

When Alexander Hamilton, in No. 70 of The Federalist Papers, argued that the “unity of the executive” would promote “[d]ecision, activity, secrecy, and despatch,” he likely could not have imagined this “unity” being used two centuries down the road to threaten one of America’s most fundamental international alliances [1]. Yet, this is precisely the power President Donald J. Trump has recently threatened to wield, in order to unilaterally withdraw from the North Atlantic Treaty Organization (NATO) [2].

Article II of the Constitution, while vesting the President with broad “executive Power,” still leaves open the specific areas to which such authority should extend [3]. Unitary Executive Theory (UET), the belief that executive power should remain concentrated in only the President, has thus developed as one strong interpretation of that constitutional grant. Considering prior judicial precedents, this article argues that a certain level of executive unity should exist in international relations. This is especially true where consistency in foreign affairs and the protection of domestic security require a single presidential voice. However, UET should not apply to withdrawal from international legal commitments or treaties that involve congressional participation in their formation or prior authorization. These agreements represent instances in which Congress has a constitutional stake in the international arena, and any attempt to withdraw from such arrangements should likewise involve joint executive-congressional participation.

Several Supreme Court cases have addressed the question of a unitary executive in international relations, offering more clarity for which areas unitary Presidential control is appropriate. These cases emphasize the executive’s importance in maintaining consistency and ensuring effective responses in matters affecting domestic security. In United States v. Curtiss-Wright Export Corp. (1936), the Supreme Court upheld a joint resolution passed by Congress that delegated to President Franklin D. Roosevelt the power to prohibit arms sales to Bolivia and Paraguay during the Chaco War if he determined that doing so would help restore peace. Curtiss-Wright argued that this delegation constituted an unconstitutional transfer of typically legislative authority over foreign trade. Justice George Sutherland, writing for the majority, noted that the President may validly exercise broad discretion in foreign affairs because of the need for secrecy, speed, and unity in negotiations. He also emphasized the President’s heightened responsibility for national security in this “vast external realm.” Significantly, Sutherland separated executive authority in domestic affairs from that on the international front, in which the court decided the President “alone” possesses the institutional capacity to “speak or listen as a representative of the nation.” This case thus placed a clear emphasis on the unique nature of international relations and the judiciary’s willingness to tolerate broader presidential discretion when efficiency and a united national voice are necessary in responding to external powers [4].

The Supreme Court echoed this necessity for a unified voice in Zivotofsky v. Kerry (2015), where Congress attempted to require the State Department to list “Israel” as the birthplace on the passport of an American citizen born in Jerusalem. Previously, however, the Executive Branch had already refused to formally recognize Israeli sovereignty over parts of the city. Since the State Department is a central agency under presidential power, this case became a question of whether Congress could depart from unitary decisions made by the executive in this area. Justice Anthony Kennedy, writing the opinion of the Court, argued that recognition of foreign states is an executive power, citing Article II’s Reception Clause. This clause allows the President to receive foreign ambassadors—a power traditionally understood to connote recognition of a foreign state. Kennedy further wrote that maintaining a consistent legal position in recognition is important, connecting this need for executive control to Hamilton’s argument in Federalist No. 70 that unity promotes “[d]ecision, activity, secrecy, and dispatch” [5]. Here, the functionality of a unitary executive is apparent, providing the United States with a singular and legally authoritative stance on international matters [6].

Another area in which the use of executive power has been validated is in circumstances where domestic security is ostensibly under threat. In Trump v. Hawaii (2018), the Supreme Court upheld President Trump’s travel restrictions on several countries after the administration concluded that their entry posed risks to national security. In delivering the opinion of the Court, Chief Justice John Roberts pointed to the Immigration and Nationality Act established by Congress, which “vests the President with the authority to restrict the entry of aliens” in situations implicating a threat to national interests. Additionally, Chief Justice Roberts stressed the position of the executive to effectively evaluate and flexibly respond to questions of national security in a way that is unmatched by the judiciary. This reasoning is especially deferential to presidential power over fact-finding in international affairs; Justice Sonia Sotomayor noted in her dissent that the issue of national security was “new window dressing” offered after the fact to conceal that Trump’s reasoning for this ban actually arose from discrimination against Muslims. Only a year later, the Supreme Court policed the same use of post hoc “window dressing” in Department of Commerce v. New York (2019). In this case, the Court rejected the executive’s push to add a “citizenship” question to the 2020 decennial census, finding that the Trump administration’s rationale appeared to have been constructed after the fact [7]. That both cases scrutinized presidential intent yet produced starkly different outcomes suggests the Court affords greater deference to executive action in foreign affairs than in domestic contexts [8].

Notably, however, all three of these precedents support the idea of an unitary executive while maintaining that executive power should not bypass congressional lawmaking. In both Curtiss-Wright and Trump v. Hawaii, the Court upheld specified authorities that had already been explicitly vested in the President by Congress. On the matter of treaties, Curtiss-Wright itself notes that while the President should retain sole discretion to negotiate, he still requires the two-thirds advice and consent of the Senate [9]. This requirement, set out in Article II, Section 2’s Treaty Clause, applies when transforming negotiations into a binding legal agreement [10]. Zivotofsky likewise acknowledges this limit, emphasizing that “[t]he Executive is not free from the ordinary controls and checks of Congress merely because foreign affairs are at issue” [11]. Simultaneously, though, the Court identified in Zivotofsky that certain powers have been historically understood—even by Congress itself—to fall under presidential jurisdiction. Congressional action in such matters, such as foreign recognition in this case, does not carry controlling authority. These precedents therefore support a unified voice in areas of foreign affairs where executive authority has been determined to be effective and necessary, but not without respect for the constitutional role of the other governmental branches, particularly Congress, in ensuring that such authority remains within its proper limits.

Based on this reasoning, President Trump’s claim to unilaterally back out of international treaties such as NATO constitutes an overstep of executive authority over foreign affairs. On a constitutional front, as Harold Hongju Koh argues in his Yale Law Journal essay, “Presidential Power to Terminate International Agreements,” the withdrawal process for a treaty should mirror the method of entry. The notion that the Executive Branch may alone decide to withdraw from a treaty therefore appears inconsistent with Article II’s Treaty Clause, which clearly requires both the President and the advice and consent of two-thirds of the Senate to enter into that same treaty. Not to mention, as Koh notes, many of these treaties implicate constitutional responsibilities shared with Congress, such as military commitments, appropriations, and foreign commerce. Given the relevance of these issues to congressional concerns, the argument that the executive branch is institutionally better positioned to act alone in these circumstances becomes far less applicable [12].

Koh further indicates that there is no strong Supreme Court precedent supporting unilateral presidential withdrawal from treaties. The case most often cited in support of unilateral presidential withdrawal is Goldwater v. Carter (1979), which arose when President Jimmy Carter unilaterally terminated the U.S.–Taiwan Mutual Defense Treaty in order to establish diplomatic relations with the People’s Republic of China. Senator Barry Goldwater and other members of Congress disputed Carter’s sole decision to terminate this agreement, arguing for the requirement of two-thirds Senate approval to parallel treaty ratification. Upon evaluating this case, however, the Supreme Court ultimately deemed it as overly political and thus not justiciable, particularly as Congress had not brought a unified, formal challenge against Carter. Thus, Koh believes Goldwater v. Carter left open the question of whether Presidents can unilaterally terminate treaties when the Senate is involved in ratification [13].

Other legal scholars, such as Curtis A. Bradley and Jack L. Goldsmith in their Harvard Law Review article “Presidential Control Over International Law,” echo Koh’s conclusion regarding the ambiguity surrounding treaties in which Congress has a stake. In building their analysis, Bradley and Goldsmith elaborate on another aspect of unilateral presidential power that Koh focuses on less: the creation of the treaty by the executive branch itself. Referencing Yale Law Professor Oona Hathaway’s work in this area, Bradley and Goldsmith underscore that over 90% of modern U.S. international agreements bypass the Article II Treaty Clause, using alternative mechanisms that involve little to no meaningful congressional input. Only about 6–7% reflect genuine interbranch collaboration. Most instead derive either from the President’s independent constitutional authority or from prior congressional delegation—whether by treaty or statute. Although Bradley and Goldsmith indicate that unilateral termination of non–Article II agreements with minimal congressional involvement is generally tolerated, agreements involving more direct congressional participation, including ex ante congressional–executive agreements, raise greater legal uncertainty. Given Bradley and Goldsmith’s observation that presidents have clear authority to terminate only those agreements “made by Presidents based on their own constitutional authority,” Article II agreements such as NATO, entered into through Senate approval, would seem to fall even further outside the scope of unilateral executive power [14].

Koh, Bradley, and Goldsmith, as well as the three previously cited cases, all suggest that President Trump’s unilateral claim to terminating international treaties in which Congress has a clear constitutional stake lacks both judicial and constitutional support. Executive power has proved legally defensible in areas where authority has been explicitly delegated by Congress, or where the President is institutionally best positioned to act independently. That rationale, however, even when it authorizes the President to conclude certain international agreements unilaterally, does not extend to terminating agreements that require congressional approval or involvement. In these agreements, the President is acting in a way that goes beyond the scope of delegated authority and instead allows the Executive to undo a jointly established legal framework. This action is what distinguishes the termination of international treaties from other exercises of executive power, as it directly undermines a process that required interbranch collaboration. Since that termination effectively reverses a process that required joint participation, it follows that similar joint participation should be required for the President to lawfully withdraw from such agreements.

Such a blanket refusal of unitary executive power over treaty abrogation involving congressional stakes may seem more a response to the current political circumstances than a long-term standard the judiciary should be setting. Perhaps, one might argue, President Trump is an exception to typical Presidents who may use power to revoke treaties more effectively and in keeping with national interests. However, this is a principle that should be established for all Presidents, regardless of their desire to infringe upon constitutional limits on shared treaty authority or not. The Constitution and even United States v. Curtiss-Wright Export Corp.—which provides broad executive power for foreign affairs—make it clear enough that President’ unitary powers do not extend to all international treaties. Otherwise, the President should have the sole discretion of making every treaty themselves.

Moreover, unity of voice in international affairs in principle does not present the most effective way to deal with treaty withdrawal. As Koh mentions, giving the President such power could “weaken systemic stability and the negotiating credibility and leverage of all Presidents,” as even the decisions of one President who uses this power to make hasty or unwise choices can be detrimental to the U.S.’s reputation on the international stage. To prove this point, Koh refers to the recent example of President Trump’s abrupt withdrawal from the Iran Nuclear Deal while negotiating a similar denuclearization agreement with North Korea. [15].

President Trump’s decisions, even if a more extreme exception, serve as a reminder of the long-term impacts that too flexible a use of executive power can have, especially in high-stakes negotiations with foreign powers. Such use directly undermines the very reason for which courts have historically vested a unified foreign-affairs voice in the President: to project a consistent national front and preserve American credibility abroad. Thus, a clear limitation on UET in withdrawing from legal agreements with foreign states remains the most effective route to maintaining the United States’s international standing and constitutional stability. With this limitation, America may better live up to Hamilton’s conception of “unity” as a legitimate mechanism for strengthening the nation on today’s ever-changing global stage [16].

Footnotes
[1] Alexander Hamilton, “The Federalist Papers: No. 70,” in The Federalist Papers (1788), https://avalon.law.yale.edu/18th_century/fed70.asp.
[2] Christian Edwards, “Trump Suggests in New Interviews He Is ‘Absolutely’ Considering Withdrawing US from ‘Paper Tiger’ NATO,” CNN, April 1, 2026, https://www.cnn.com/2026/04/01/middleeast/trump-nato-us-withdrawal-intl.https://www.cnn.com/2026/04/01/middleeast/trump-nato-us-withdrawal-intl[.](https://www.zotero.org/google-docs/?k40BKz)
[3] Constitution of the United States, § Article II (1787), https://constitution.congress.gov/constitution/article-2/[.](https://www.zotero.org/google-docs/?Y1A3v3)
[4] United States v. Curtiss-Wright Export Corp., 299 U.S. 304 (Supreme Court of the United States 1936), https://supreme.justia.com/cases/federal/us/299/304/[.](https://www.zotero.org/google-docs/?wr6JL4)
[5] Alexander Hamilton, “The Federalist Papers: No. 70.”
[6] Zivotofsky v. Kerry, 576 U.S. 1 (Supreme Court of the United States 2015), https://supreme.justia.com/cases/federal/us/576/1/.
[7] Department of Commerce v. New York, 588 U.S ___ (Supreme Court of the United States 2019), https://supreme.justia.com/cases/federal/us/588/18-966/.
[8] Trump v. Hawaii, 585 U.S. ___ (Supreme Court of the United States 2018), https://supreme.justia.com/cases/federal/us/585/17-965/[.](https://www.zotero.org/google-docs/?XwLLou)
[9] United States v. Curtiss-Wright Export Corp.
[10] Constitution of the United States.
[11] Zivotofsky v. Kerry.
[12] Harold Hongju Koh, “Presidential Power to Terminate International Agreements,” The Yale Law Journal 128 (November 2018): 432–61.
[13] Koh, “Presidential Power to Terminate International Agreements,” 432–61; Goldwater v. Carter, 444 U.S. 996 (Supreme Court of the United States 1979), https://supreme.justia.com/cases/federal/us/444/996/.
[14] Curtis A. Bradley and Jack L. Goldsmith, “Presidential Control Over International Law,” Harvard Law Review 131, no. 5 (2018): 1206–26.
[15] Koh, “Presidential Power to Terminate International Agreements,” 432–61.
[16] Alexander Hamilton. “The Federalist Papers: No. 70.”