Government
Type: Parliamentary.
Constitution: No formal, written constitution.
Independence: Declared a dominion in 1907.
Branches: Executive--Queen Elizabeth II (chief of state, represented by a governor general), prime minister (head of government), cabinet. Legislative--unicameral House of Representatives, commonly called parliament. Judicial--three-level system: District Courts, the High Court, and the Court of Appeals, with further appeal possible to the Judicial Committee of the Privy Council. There also are specialized courts, such as employment court, family courts, youth courts, and the Maori Land Court.
Administrative subdivisions: 12 regions with directly elected councils and 74 districts (15 of which are designated as cities) with elected councils. There also are a number of community boards and special-purpose bodies with partially elected, partially appointed memberships.
Political parties: Labour, National, the Jim Anderton's Progressive Coalition Party, New Zealand Green Party, New Zealand First, ACT, United Future, and several smaller parties not represented in Parliament.
Suffrage: Universal at 18.

Government of New Zealand
New Zealand has a parliamentary system of government closely patterned on that of the United Kingdom and is a fully independent member of the Commonwealth. It has no written constitution.

Executive authority is vested in a Cabinet led by the prime minister, who is the leader of the political party or coalition of parties holding the majority of seats in Parliament. All Cabinet ministers must be members of Parliament and are collectively responsible to it.

The unicameral Parliament (House of Representatives) has 120 seats, six of which currently are reserved for Maori elected on a separate Maori roll. However, Maori also may run for, and have been elected to, nonreserved seats. Parliaments are elected for a maximum term of 3 years, although elections can be called sooner.

The judiciary consists of the Court of Appeals, the High Court, and the District Courts. New Zealand law has three principal sources--English common law, certain statutes of the U.K. Parliament enacted before 1947, and statutes of the New Zealand Parliament. In interpreting common law, the courts have been concerned with preserving uniformity with common law as interpreted in the United Kingdom. This uniformity is ensured by the maintenance of the Privy Council in London as the final court of appeal and by judges' practice of following British decisions, even though, technically, they are not bound by them.

Local government in New Zealand has only the powers conferred upon it by Parliament. The country's 12 regional councils are directly elected, set their own tax rates, and have a chairman elected by their members. Regional council responsibilities include environmental management, regional aspects of civil defense, and transportation planning. The 74 "territorial authorities"--15 city councils, 58 district councils in rural areas, and one county council for the Chatham Islands--are directly elected, raise local taxes at rates they themselves set, and are headed by popularly elected mayors. The territorial authorities may delegate powers to local community boards. These boards, instituted at the behest either local citizens or territorial authorities, advocate community views but cannot levy taxes, appoint staff, or own property.
source: http://www.state.gov