Constitution of New Zealand

New Zealand has no single constitutional document; its constitution is instead an uncodified amalgamation of written and unwritten sources, chief among them the Constitution Act 1986, the 1840 Treaty of Waitangi, the New Zealand Bill of Rights Act 1990, assorted imperial statutes including Magna Carta and the Bill of Rights 1689, and constitutional convention. It establishes a constitutional monarchy with parliamentary sovereignty exercised through a unicameral House of Representatives, the upper Legislative Council having been abolished in 1950, and it has used a mixed-member proportional electoral system since 1996, following the country's 1947 adoption of the Statute of Westminster and full legislative independence.