Government
Type: Constitutional hereditary monarchy.
Constitution: 1875 (revised 1970).
Independence: June 4, 1970.
Branches: Executive--Prime Minister and Cabinet appointed by the King. Legislative--unicameral Legislative Assembly. Judicial--Court of Appeals (Privy Council), Supreme Court, Land Court, Magistrates' Court.
Administrative subdivisions: Three main island groups--Ha'apai, Tongatapu, Vava'u.
Political parties: None.
Suffrage: Universal at age 21.
Central government budget (2003 est.): $75.2 million.
Flag: Red field with red cross enclosed in white square on upper left quarter.

Government of Tonga
Tonga is the South Pacific's last Polynesian kingdom. Its executive branch includes the prime minister and the cabinet, which becomes the Privy Council when presided over by the monarch. In intervals between legislative sessions, the Privy Council makes ordinances, which become law if confirmed by the legislature. The unicameral Legislative Assembly is controlled by the royal family and noble families. It consists of nine nobles who are elected by the 33 hereditary nobles of Tonga and nine people's representatives elected by universal adult suffrage for 3-year terms. The Legislature also includes 12 cabinet ministers, appointed by the monarch. The governor of Ha'apai and Vava'u are appointed to their offices and serve as exofficio members of the cabinet. The Legislative Assembly sits for 4 or 5 months a year.

Tonga's court system consists of the Court of Appeal (Privy Council), the Supreme Court, the Magistrates' Court, and the Land Court. Judges are appointed by the monarch.

The only form of local government is through town and district officials who have been popularly elected since 1965. The town official represents the central government in the villages, the district official has authority over a group of villages.
source: http://www.state.gov