The UN Charter is the foundational treaty of the United Nations, serving as the cornerstone of public international law and establishing the organization's structure and principles. Its origin traces back to the Atlantic Charter of August 14, 1941, and it was created to solve the problem of global conflict following World War II. The Charter was signed on June 26, 1945, in San Francisco, and officially came into force on October 24, 1945, establishing a system for maintaining international peace and security.
The Charter works by codifying major principles, such as the sovereign equality of all its Members and the prohibition of the threat or use of force in international relations, as stated in Article 2(4). Key mechanisms are outlined in its chapters: Chapter VI addresses the peaceful settlement of disputes, while Chapter VII empowers the Security Council to take enforcement measures, including sanctions or military force, with respect to threats to the peace. The Charter connects to the six principal organs it established: the General Assembly, Security Council, Economic and Social Council (ECOSOC), Trusteeship Council, International Court of Justice (ICJ), and the Secretariat. The Statute of the International Court of Justice is annexed to the Charter and forms an integral part of it, as per Article 92.
The Charter has been amended three times, in 1963, 1965, and 1973, but its core principles remain the same. The most significant changes involved expanding the membership of the Security Council from 11 to 15 members and the Economic and Social Council from 18 to 54 members. Specifically, the amended Article 27 increased the required affirmative votes for non-procedural Security Council decisions from seven to nine, including the concurring votes of the five permanent members.