The United Nations Charter is the constitution of the United Nations. It was signed at San Francisco on June 26, 1945 by the 50 original member countries. It entered into force on October 24, 1945, after being ratified by the five founding members—the Republic of China, France, the Soviet Union, the United Kingdom, and the United States—and a majority of the other signatories.
As a treaty, all signatories are bound by international law to obey the provisions of the Charter. The Charter was ratified by the United States on August 8, 1945, making that nation the first to join the new international organization.
The United Nations Charter has been enacted into law in the United States by virtue of its being ratified as a treaty, making it binding on the executive branch of the government. This is relevant to the Bush doctrine of pre-emptive war, which some believe violates the Charter.
