The Treaty Clause (Article II, Section 2, Clause 2) divides diplomatic power between the executive and the legislature: the president negotiates, but the Senate must ratify by a two-thirds supermajority. Alexander Hamilton explained in Federalist No. 75 that treaties "partake of the nature of laws" — they can alter domestic obligations, bind future Congresses, and commit the nation to war — and therefore require a higher threshold than ordinary legislation. The two-thirds bar was itself a compromise at the 1787 Constitutional Convention between delegates who wanted the Senate to hold sole treaty power and those who feared any Senate majority could bind the nation to harmful commitments.
In practice, the Senate has used this power to block major agreements. The 1919 Treaty of Versailles ending World War I failed twice because 38 senators held firm, keeping the United States out of the League of Nations. The Reagan administration's 1979 SALT II arms control treaty stalled in the Senate over Soviet policy objections and was never ratified. Presidents increasingly route foreign commitments through executive agreements — which require no Senate vote — precisely because the two-thirds bar is so hard to clear. Between 1940 and 1989, the United States signed 13,016 executive agreements but only 759 formal treaties.
The clause's limits are contested. What counts as a "treaty" requiring Senate ratification versus an "executive agreement" the president can sign alone has never been definitively resolved by the Supreme Court. Presidents decide which form to use, and that choice determines whether any future president can undo the commitment alone or must work with the Senate to exit.
The Treaty Clause determines whether international commitments outlast the president who made them. A Senate-ratified treaty survives administrations and signals broad domestic consensus; an executive agreement can be revoked by the next president on Day 1. Understanding this distinction explains why the same U.S. commitment can be binding in one administration and nonexistent in the next.
People often think all significant international agreements must go through the Senate. In practice, the president chooses the form — treaty or executive agreement — and most international commitments today are executive agreements requiring no Senate vote. The 2015 Iran nuclear deal, NATO status of forces agreements, and the 1981 Algiers Accords ending the Iran hostage crisis were all executive agreements, not formal treaties.
The Treaty Clause determines whether international commitments outlast the president who made them. A Senate-ratified treaty survives administrations and signals broad domestic consensus; an executive agreement can be revoked by the next president on Day 1. Understanding this distinction explains why the same U.S. commitment can be binding in one administration and nonexistent in the next.
People often think all significant international agreements must go through the Senate. In practice, the president chooses the form — treaty or executive agreement — and most international commitments today are executive agreements requiring no Senate vote. The 2015 Iran nuclear deal, NATO status of forces agreements, and the 1981 Algiers Accords ending the Iran hostage crisis were all executive agreements, not formal treaties.