Japan is governed under the constitution of 1947, drafted by the Allied occupation authorities and approved by the Japanese Diet. It declares that the emperor is the symbol of the state but that sovereignty rests with the people. Executive power is vested in a cabinet appointed and headed by the prime minister, who is elected by the Diet and is usually the leader of the majority party in that body. Japan's bicameral Diet has sole legislative power. The House of Representatives has 480 members, who are popularly elected for four-year terms; approximately three fifths of them are chosen by single-seat constituencies and the rest proportionally. The House of Councilors has 242 members; they are elected for six-year terms. A supreme court heads an independent judiciary. Administratively, Japan is divided into 47 prefectures, each governed by a popularly elected governor and unicameral legislature.