Kuwait is a monarchy governed under the constitution promulgated in 1962. The emir, the hereditary monarch of the Mubarak line of the ruling al-Sabah family, serves as head of state. The government is headed by the prime minister, who is appointed by the monarch; until 2003 the prime minister traditionally was the crown prince. The unicameral legislature consists of the 50-seat National Assembly, whose members are elected by popular vote to serve four-year terms. There are no official political parties, although several political groups act as de facto parties. Administratively, the country is divided into six governorates.