The Treaty Clause has a number of striking features. It gives the Senate, in James Madison’s terms, a “partial agency” in the president’s foreign-relations power. The clause requires a supermajority (two-thirds) of the Senate for approval of a treaty, but it gives the House of Representatives, representing the “people,” no role in the process.

Midway through the Constitutional Convention, a working draft had assigned the treaty-making power to the Senate, but the Framers, apparently considering the traditional role of a nation-state’s executive in making treaties, changed direction and gave the power to the president, with the proviso of the Senate’s “advice and consent.” In a formal sense, then, treaty-making became a mixture of executive and legislative power. Most people of the time recognized the actual conduct of diplomacy as an executive function, but under Article VI treaties were, like statutes, part of the “supreme Law of the Land.” Thus, as Alexander Hamilton explained in The Federalist No. 75, the two branches were appropriately combined:

The qualities elsewhere detailed as indispensable in the management of foreign negotiations point out the executive as the most fit agent in those transactions; while the vast importance of the trust and the operation of treaties as laws plead strongly for the participation of the whole or a portion of the legislative body in the office of making them.

Another reason for involving both president and Senate was that the Framers thought American interests might be undermined by treaties entered into without proper reflection. The Framers believed that treaties should be strictly honored, both as a matter of the law of nations and as a practical matter, because the United States could not afford to give the great powers any cause for war. But this meant that the nation should be doubly cautious in accepting treaty obligations. As James Wilson said, “Neither the President nor the Senate, solely, can complete a treaty; they are checks upon each other, and are so balanced as to produce security to the people.”

The fear of disadvantageous treaties also underlay the Framers’ insistence on approval by a two-thirds majority of the Senate. In particular, the Framers worried that one region or interest within the nation, constituting a bare majority, would make a treaty advantageous to it but prejudicial to other parts of the country and to the national interest. An important episode under the Articles of Confederation had highlighted the problem. The United States desired a trade treaty with Spain and sought free access to the Mississippi River through Spanish-controlled New Orleans. Spain offered favorable trade terms, but only if the United States would give up its demands on the Mississippi. The Northern states, which would have benefited most from the trade treaty and cared little about New Orleans, had a majority, but not a supermajority, in the Continental Congress. Under the Articles of Confederation, treaties required assent of a supermajority (nine out of thirteen) of the states, and the South was able to block the treaty. It was undoubtedly that experience that impelled the Framers to carry over the supermajority principle from the Articles of Confederation, as the Southern states (and many people in the North) concluded that the supermajority requirement had prevented an unwise treaty.

At the Convention, several prominent Framers argued unsuccessfully to have the House of Representatives included. But most delegates thought that the House had substantial disadvantages when it came to treaty-making. For example, as a large body, the House would have difficulty keeping secrets or acting quickly. The small states, wary of being disadvantaged, also preferred to keep the treaty-making power in the Senate, where they had proportionally greater power.

The ultimate purpose, then, of the Treaty Clause was to ensure that treaties would not be adopted unless most of the country stood to gain. True, treaties would be more difficult to adopt than statutes, but the Framers realized that an unwise statute could simply be repealed, while an unwise treaty remained a binding international commitment that would not be so easy to unwind.

Other questions, however, remained. First, are the provisions of the clause exclusive—that is, does it provide the only way that the United States may enter into international obligations?

While the clause does not say, in so many words, that it is exclusive, its very purpose—not to have any treaty disadvantage one part of the nation by a bare majority’s approval—suggests that no other route is possible, whether through the president’s acting alone or through ordinary legislation with the popularly elected House’s having a role. Further, the drafting and ratifying debates reflect a broad consensus that the clause was the only constitutional avenue for treaty-making. Nonetheless, while it appears that the Treaty Clause was, in the original understanding, the exclusive way to make treaties, the Framers also apparently recognized a class of less-important international agreements, not rising to the level of “treaties,” which could be approved in some other way. Article I, Section 10, in describing restrictions upon the states, speaks of “Treat[ies]” and “Agreement[s] . . . with a foreign Power” as two distinct categories. Some scholars believe this shows that not all international agreements are treaties, and that these other agreements would not need to go through the procedures of the Treaty Clause. Instead, the president, in the exercise of his executive power, could conclude such agreements on his own. This exception for lesser agreements would have to be limited to “agreements” of minor importance, or else it would provide too great an avenue for evasion of the protections the Framers placed in the Treaty Clause.

A second question is how the president and Senate should interact in their joint exercise of the treaty power. Many Framers apparently thought that the president would oversee the actual conduct of diplomacy, but that the Senate would be involved from the outset as a sort of executive council advising the president. This was likely a reason that the Framers thought the smaller Senate was more suited than the House to play a key role in treaty-making. In the first effort at treaty-making under the Constitution, President George Washington attempted to operate in just this fashion. He went to the Senate in person to discuss a proposed treaty before he began negotiations. What is less clear, however, is whether the Constitution actually requires this process, or whether it is only what the Framers assumed would happen. The Senate, of course, is constitutionally authorized to offer “advice” to the president at any stage of the treaty-making process, but the president is not directed (in so many words) as to when advice must be solicited. The Appointments Clause, which appears in the same sentence of Article II, Section 2, as the Treaty Clause, also requires the “advice and consent of the Senate,” but it seems evident (and post-ratification practice confirms) that this is satisfied by a Senate vote on a finalized presidential proposal and does not require the Senate’s “advice” throughout the selection process. As we shall see, this uncertainty has led, in modern practice, to a very different procedure than some Framers envisioned. It seems clear, however, that the Framers expected that the Senate’s “advice and consent” would be a close review and not a mere formality, as they thought of it as an important check upon presidential power.

A third difficult question is whether the Treaty Clause implies a Senate power or role in treaty termination. Scholarly opinion is divided, and few Framers appear to have discussed the question directly. One view sees the power to make a treaty as distinct from the power of termination, with the latter being more akin to a power of implementation. Since the Constitution does not directly address the termination power, this view would give it to the president as part of the president’s executive powers to conduct foreign affairs and to execute the laws. When the termination question first arose in 1793, Washington and his cabinet, which included Hamilton and Thomas Jefferson, embraced this view. All of them thought Washington could, on his own authority, terminate the treaty with France if necessary to keep the United States neutral.

An alternative view holds that, as a matter of the general eighteenth-century understanding of the legal process, the power to take an action (such as passing a statute or making a treaty) implies the power to undo the action. This view would require the consent of the president and a supermajority of the Senate to undo a treaty. There is, however, not much historical evidence that many Framers actually held this view of treaty termination, and it is inconsistent with the common interpretation of the Appointments Clause (under which Senate approval is required to appoint but not to remove executive officers).

A third view is that Congress as a whole has the power to terminate treaties, based on an analogy between treaties and federal laws. When the United States first terminated a treaty in 1798 under President John Adams, this procedure was adopted, but there was little discussion of the constitutional ramifications. Moreover, when there is a conflict between a statute and a treaty, the Supreme Court has concluded that for purposes of U.S. law the last expression of the sovereign will controls, so that a later-enacted statute overrides an earlier-enacted treaty and vice versa. The Cherokee Tobacco (1870).

Finally, there is a question of the limits of the treaty power. A treaty presumably cannot alter the constitutional structure of government, and the Supreme Court has said that executive agreements—and so apparently treaties—are subject to the limits of the Bill of Rights just as ordinary laws are. Reid v. Covert (1957). In Geofroy v. Riggs (1890), the Court also declared that the treaty power extends only to topics that are “properly the subject of negotiation with a foreign country.” However, at least in the modern world, one would think that few topics are so local that they could not, under some circumstances, be reached as part of the foreign-affairs interests of the nation. Some scholars have argued that treaties are limited by the federalism interests of the states. The Supreme Court rejected a version of that argument in Missouri v. Holland (1920), holding that the subject matter of treaties is not limited to the enumerated powers of Congress. The revival of interest in federalism limits on Congress in such areas as state sovereign immunity, see Seminole Tribe of Florida v. Florida (1996), and the Tenth Amendment, see Printz v. United States (1997), raises the question whether these limits also apply to the treaty power, but the Court has not yet taken up these matters.

Turning to modern practice, the Framers’ vision of treaty-making has in some ways prevailed and in some ways been altered. First, it is not true—and has not been true since George Washington’s administration—that the Senate serves as an executive council to advise the president in all stages of treaty-making. Rather, the usual modern course is that the president negotiates and signs treaties independently and then presents the proposed treaty to the Senate for its approval or disapproval. Washington himself found personal consultation with the Senate to be so awkward and unproductive that he abandoned it, and subsequent presidents have followed his example.

Moreover, the Senate frequently approves treaties with conditions and has done so beginning with the Washington administration. If the president makes clear to foreign nations that his signature on a treaty is only a preliminary commitment subject to serious Senate scrutiny, and if the Senate takes seriously its constitutional role of reviewing treaties (rather than merely deferring to the president), the check that the Framers sought to create remains in place. By going beyond a simple “up-or-down” vote, the Senate retains some of its power of “advice”: the Senate not only disapproves the treaty proposed by the president but suggests how the president might craft a better treaty. As a practical matter, there is often consultation between the executive and members of the Senate before treaties are crafted and signed.

A more substantial departure from the Framers’ vision may arise from the practice of executive agreements. Presidents have made minor agreements on their own authority since soon after ratification, and some scholars find this practice consistent with the original meaning of the Constitution. Article I, Section 10 indicates that the Framers recognized a category of “agreements” that did not rise to the level of “treaties,” because individual states in the Union are prohibited from making the latter but can make the former with the consent of Congress. The president’s Article II, Section 1, “executive power” thus might be understood to encompass the power to make agreements that are not treaties (although other scholars doubt that the grant of “executive power” was intended to convey this or any other substantive power).

Although initially a minor diplomatic tool, executive agreements increased enormously in their frequency and importance during the New Deal and World War II. After the Second World War, a number of important agreements were concluded by the president and approved by a majority of both houses of Congress without being submitted for the Senate’s supermajority approval. According to the Restatement (Third) of the Foreign Relations Law of the United States, Section 303 (1987), the president may validly conclude executive agreements that: (1) cover matters that are solely within his executive power, or (2) are made pursuant to a treaty, or (3) are made pursuant to a legitimate act of Congress. Section 303 further states that treaties and congressional-executive agreements are generally regarded as fully interchangeable as constitutional methods of agreement making, and many scholars continue to find this statement an accurate assessment.

When the president acts pursuant to a prior treaty, there seems to be little tension with the Framers’ vision, as Senate approval has, in effect, been secured in advance. The modern practice of congressional-executive agreements, by which some international agreements have been made by the president and approved (either in advance or after the fact) by a simple majority of both houses of Congress, rather than two-thirds of the Senate, is more troubling. In modern times, post-signature approval by Congress has been especially common for trade agreements, such as the North American Free Trade Agreement (NAFTA), the agreement establishing the World Trade Organization, and other bilateral and regional free trade agreements. International trade, especially tariffs, is an area of Congress’s particular constitutional interest, and congressional-executive agreements, at least with respect to trade matters, are now well established. Some scholars regard two cases from the late nineteenth and early twentieth centuries as indirectly approving congressional-executive agreements in the trade area, although the Court did not elaborate its rationale. Field v. Clark (1892); B. Altman & Co. v. United States (1912). More recently, one court of appeals found a prominent court challenge to NAFTA to be a non-justiciable “political question.” Made in the USA Foundation v. United States (2001). The practice now appears so settled that it is unlikely to be overturned or even substantially questioned.

On the other hand, arguments for “complete interchangeability”—that is, claims that anything that can be done by treaty can be done by congressional-executive agreement—seem counter to the Framers’ intent and unconfirmed by modern practice. The Framers carefully considered the supermajority rule for treaties and adopted it in response to specific threats to the Union; finding a complete alternative to the Treaty Clause would in effect eliminate the supermajority rule and make important international agreements easier to adopt than the Framers wished. Despite the rise of congressional-executive agreements, Article II, Section 2, treaties remain an important part of U.S. international agreement-making. Outside the trade area, in recent years the most important international agreements—including in critical areas such as arms control, human rights, the environment, tax, and extradition—have been submitted for the Senate’s advice and consent under the Treaty Clause. The Senate has refused to approve several key high-profile agreements, including the Comprehensive Nuclear Test Ban Treaty and the Law of the Sea Treaty, and it has not been thought that these refusals could be avoided through an alternative means of agreement-making. At the same time, agreements made by the president on the basis of prior congressional approval (often indirect or implicit approval) remain the most numerous type of U.S. international agreement, although typically they involve less important matters. Recent scholarship has challenged the Restatement’s claim of complete equivalence between treaties and congressional-executive agreements, but there has not been consensus upon the appropriate constitutional roles of the two forms of agreement-making.

The third type of executive agreement is one adopted by the president without formal approval by either the Senate or Congress as a whole. The Supreme Court and modern practice embrace the idea that the president may under some circumstances make these so-called sole executive agreements. United States v. Belmont (1937); United States v. Pink (1942). But the scope of this independent presidential power remains a serious question. The Pink and Belmont cases involved agreements relating to the recognition of a foreign government, a power closely tied to the president’s textual power to receive ambassadors (Article II, Section 3). The courts have consistently permitted the president to settle foreign claims by sole executive agreement, but at the same time have emphasized that Congress has acquiesced in the practice. Dames & Moore v. Regan (1981); American Insurance Ass’n v. Garamendi (2003); Medellin v. Texas (2008).

The president is also widely believed to have some executive agreement-making power in military affairs flowing from his power as commander in chief. Beyond this, the modern limits of the president’s ability to act independently in making international agreements have not been explored by the courts, although modern scholarship tends to be critical of an expansive presidential power to make sole executive agreements, and the Court in the Medellin case seemed to read it narrowly, at least where it would have implications for domestic U.S. law.

With respect to treaty termination, modern practice allows the president to terminate treaties on his own, at least where termination is permitted by a treaty’s terms. In noteworthy episodes, President James Earl Carter terminated the Mutual Defense Treaty between the United States and the Republic of China (Taiwan) in 1980, and President George W. Bush terminated the Anti-Ballistic Missile Treaty with the Soviet Union in 2002, six months after announcing that the United States would withdraw from that treaty. Some senators objected to President Carter’s actions, but the Supreme Court rebuffed their challenge in Goldwater v. Carter (1979), albeit without a clear explanation of its holding. President Bush’s action was criticized by some scholars but received general acquiescence and some academic defense. In light of the consensus early in George Washington’s administration, it is probably fair to say that this sort of presidential treaty termination does not obviously depart from the original understanding, inasmuch as the Framers were much more concerned about checks upon entering into treaties than they were about checks upon terminating them. On the other hand, the president’s constitutional ability to terminate or suspend treaties in violation of their terms remains more contested because of the president’s textual obligation to faithfully execute the laws (as treaties are declared to be laws by Article VI). A proposal early in the George W. Bush administration to “suspend” the Geneva Conventions on the treatment of prisoners of war, as applied to terrorism suspects determined to be “unlawful combatants” in the war on terror, was sharply criticized on this ground and ultimately not adopted by the president. Some scholars would say, however, that the president’s treaty termination power extends even to violating treaties, especially treaties in core areas of presidential power such as the military and national defense.