The Constitution’s text does not mention a general power over foreign affairs. Nonetheless, some courts and commentators have suggested a foreign affairs power of the federal government arising either from a combination of the text’s specific foreign affairs–related powers, from the structural implications of the federal system, or from the inherent powers of sovereignty all nations possess under international law.

The foreign affairs power might have three distinct implications. First, it might give Congress foreign affairs powers beyond those listed in Article I, Section 8, or elsewhere in the text. Second, it might mean that the president has foreign affairs powers that do not arise from Article II or from grants of power from Congress. Third, it might preclude the states from acting in ways that interfere with the federal government’s exercise of the foreign affairs power (in addition to the express or implied preclusions in the Constitution’s text or in preemptive treaties or statutes).

As to the first category, consider for example the power to restrict immigration. To many people, this seems an obvious power of Congress. However, no clause of the text grants it directly, and while it might be implied from Congress’s express power over naturalization, that does not seem an obvious conclusion. Another possibility is that it arises outside the text. In Chae Chan Ping v. United States (1889), the Supreme Court found that Congress’s immigration power arose from the federal government’s possession of external sovereignty, being a power that all sovereign governments necessarily have. As recently as 2012, Justice Antonin Scalia in a dissenting opinion in Arizona v. United States, referred to the immigration power as an inherent power of the national government.

Another nineteenth-century example of Congress’s foreign affairs power is the power to acquire territory. Though he signed the treaty by which the United States obtained the Louisiana Territory, Thomas Jefferson had serious misgivings about its constitutionality. He would have preferred a constitutional amendment allowing the United States to acquire territory. That right could, nonetheless, be derived from the Treaty Clause (Article II, Section 2, Clause 2) or the Property Clause (Article IV, Section 3, Clause 2). But in Jones v. United States (1890), the Court found acquisition of territory to be an inherent power of sovereignty derived from international law that Congress could exercise without tying it to a specific constitutional power. An example nearer the framing might be the 1799 Logan Act, which prohibited private persons from conducting diplomacy; it is not obvious what enumerated power might support Congress’s action. The distinguished commentator Louis Henkin described a “Foreign Affairs Power” exercised by Congress in cases such as Jones and Chae Chan Ping and resting on “the powers of the United States inherent in its sovereignty and nationhood.” Henkin thought that, in addition, it would support, for example, Congress’s power to enact the Foreign Sovereign Immunities Act (regulating when a foreign government may be sued in United States courts), to regulate conduct of U.S. citizens that occurred abroad or otherwise affected foreign relations, and indeed to regulate any activity with international implications.

The president’s non-textual foreign affairs power is most strongly associated with Justice George Sutherland’s opinion for the Court in United States v. Curtiss-Wright Export Corp. (1936). According to Sutherland, powers of “external sovereignty” (foreign affairs powers) vested inherently in the national government at the moment of independence; thus they were never possessed by the states and so are not subject to the delegated powers rule of the Tenth Amendment. Further, according to Sutherland’s opinion, the president is the “sole organ” of the United States in foreign affairs (Sutherland did not say on what basis) and therefore the president alone exercises many of the federal government’s foreign affairs powers. Sutherland concluded on this basis that Congress can make very broad delegations to the president in foreign affairs without implicating the doctrine that Congress may not delegate or give away its law-making powers to the president. However, the case has been interpreted—especially by the executive branch—to mean that the president can exercise broad independent authority in foreign affairs without tracing it to a statutory or constitutional delegation. For example, Curtiss-Wright might be the basis of the President’s independent power to conduct diplomacy, to make international executive agreements, and to terminate treaties. In addition, the foreign affairs power might be invoked to assert that Congress acts unconstitutionally when it attempts to restrict or interfere with the president’s role as the nation’s “sole organ” in foreign affairs.

The third implication of the foreign affairs power is that states may be constitutionally prevented from participating in foreign affairs. Of course, states are precluded from certain foreign affairs–related activities by the prohibitions in Article I, Section 10, by the negative implication of other specific clauses, and often by statutes or treaties. But in Zschernig v. Miller (1968), the Supreme Court found a state law relating to foreign affairs invalid even absent a statute, treaty, or specific constitutional provision. In that case, decided against the backdrop of the Cold War, Oregon law prohibited citizens of communist countries from inheriting property from Oregon estates on the ground that such inheritances aided enemy nations. This rule (and similar ones in other states) had provoked diplomatic protests to the U.S. government. The Supreme Court found the Oregon law unconstitutional as “an intrusion by the State into the field of foreign affairs which the Constitution entrusts to the President and the Congress.” Later commentary began referring to this idea as the “dormant foreign affairs doctrine,” associating it with the dormant commerce clause doctrine that prohibits states from interfering with interstate commerce even in the absence of federal regulation.

The foreign affairs power may also support a related federal common law of foreign affairs, developed by federal courts, that displaces state law in certain instances. In Banco Nacional de Cuba v. Sabbatino (1964), the Court held that the act of state doctrine (which prohibits courts from holding invalid acts of foreign sovereigns done in their own territory) is part of federal common law and overrides state law to the contrary. Although subsequent opinions have referred to foreign affairs as an area in which federal courts can determine when federal common law displaces state legislation, the Court has not explained the boundaries of the field nor directly revisited the issue since Sabbatino. Nonetheless, lower courts have invoked the doctrine in various ways to set aside state law. At a minimum, the federal common law of foreign affairs presumably includes various common law doctrines of foreign sovereign immunity (to the extent they are not codified by statute or treaty), as well as the act of state doctrine.

It is unclear how much force the foreign affairs power has in modern law. After the mid–twentieth-century expansion of Congress’s power under the Commerce Clause and other enumerated powers, the need for Congress to rely on inherent or structural sources of foreign affairs powers has declined, and inherent congressional powers in foreign affairs have not played a material role in the modern Court’s holdings. Although the executive branch continues to rely on arguments based on Curtiss-Wright, the Court moved sharply away from the idea of inherent presidential powers in Youngstown Sheet and Tube Co. v. Sawyer (1952) (limiting the domestic impact of the president’s foreign affairs power), and the modern Court has approached questions of executive power more through the lens of Youngstown than Curtiss-Wright. For example, Dames & Moore v. Regan (1981), upholding the president’s power to settle the Iran hostage crisis, relied on congressional acquiescence in the longstanding presidential practice of claims settlement rather than on inherent presidential powers in foreign affairs. Similarly, the Court’s war-on-terror cases, such as Hamdi v. Rumsfeld (2004), have focused on congressional authorization rather than inherent presidential power. The Court has cited Curtiss-Wright in some modern cases, but it is not clear that it was important to the outcomes.

The foreign affairs power has the most potential for modern relevance in connection with the foreign affairs of the states. Globalization of commerce, transportation, and communications has brought state activities increasingly into the international spotlight. As a result, the states’ potential to interfere with national foreign policies—and, correspondingly, to have their laws challenged on that ground—seems substantial. But the Constitution’s express preclusions of the states from foreign affairs are narrow (chiefly relating to war, treaties, and import and export taxes). Thus preclusion of states from interference in foreign affairs may need to come, if at all, from the dormant foreign affairs power or federal common law or both.

Nonetheless, the Supreme Court has not rendered a definitive ruling in this area since Zschernig. On several occasions the issue seemed to be presented, but the Court’s ruling took a different route. For example, in Crosby v. National Foreign Trade Council (2000), a business group challenged a Massachusetts statute that prohibited companies doing business in Burma (Myanmar) from bidding on state contracts, a law passed in response to that nation’s poor human rights record. A lower court enjoined the state law, in part under the dormant foreign affairs power. The Supreme Court affirmed that judgment but did not reach the foreign affairs power, as it found the state law preempted by a federal statute relating to trade with Burma. In American Insurance Association v. Garamendi (2003), insurers challenged a California law relating to insurance contracts issued in Europe prior to the Holocaust; the law was apparently an effort to assist recovery by Holocaust victims and their beneficiaries, some of whom were California residents. The court of appeals rejected a Zschernig-based argument by the insurers. The Supreme Court reversed, invalidating the state law, but expressly declined to rely on Zschernig. Instead, the Court found that the California law conflicted with an executive branch policy of settling Holocaust claims through an international settlement body, established under various executive agreements, rather than by litigation in national courts. The Court did not clearly explain the constitutional basis of this preclusion. In a later case, Medellin v. Texas (2008), the Court described Garamendi as based on the president’s ability to settle international claims by executive agreement, a power recognized as deriving from Congress’s consent in Dames & Moore. Medellin refused to extend Garamendi to allow the president to override Texas’s decision to execute a Mexican citizen convicted of murder in Texas, even though the president argued (and the Court conceded) that the matter had substantial foreign policy implications.

The existence and operation of a non-textual foreign affairs power remains sharply contested in academic commentary. Modern scholarship has been highly critical of the historical underpinnings of the Curtiss-Wright opinion, while the Court’s federalism revival in domestic matters beginning in the 1990s caused scholars to devote more attention to the structural significance of the Tenth Amendment. Renewed interest in formalist and textualist approaches to the Constitution, including in foreign affairs, has cast doubt on the idea of inherent or structural powers not linked to constitutional grants. At the same time, some modern executive power scholarship supports a broad reading of the president’s constitutional foreign affairs power under the Executive Vesting Clause (Article II, Section 1) and the Commander in Chief Clause (Article II, Section 2) that would lessen the need to rely on non-textual sources of presidential power in foreign affairs.

As in the courts, the debate over the foreign affairs power in academic commentary is most significant in the area of restrictions on the states. The idea that states are restricted by non-textual sources of national foreign affairs power has been broadly challenged as inconsistent with the express exclusions of the states from some foreign affairs powers (which implies that powers not listed are not excluded). Moreover, some modern scholarship indicates that pre- and post-ratification history does not support the idea of non-textual exclusions of the states. On the other hand, the structural need for a unified national foreign policy continues to persuade some scholars of the importance of “dormant” limits on the states. Although Zschernig itself has relatively few committed defenders, various forms of non-textual preclusion continue to be strongly advocated.