Hay–Pauncefote Treaty, (1900–01), either of two agreements between Britain and the United States, the second of which freed the United States from a previous commitment to accept international control of the Panama Canal. After negotiations between U.S. Secretary of State John Milton Hay and British ambassador Lord Pauncefote on revision of the Clayton–Bulwer Treaty of 1850 (by which the two nations would jointly control a projected Central American canal), the first Hay–Pauncefote Treaty was concluded on Feb. 5, 1900. The U.S. Senate declined to ratify it because it still restricted U.S. rights over the proposed canal. The second treaty (Nov. 18, 1901), ratified by both governments, definitely abrogated the agreement of 1850 and gave the United States a free hand.