<P> New Zealand has a legislature called the New Zealand Parliament, consisting of the Queen - in - Parliament and the House of Representatives . According to the doctrine of parliamentary sovereignty, Parliament may pass any legislation that it wishes . Since 1996, New Zealand has used the Mixed Member Proportional (MMP) system, which is essentially proportional representation with single member seats (that can affect the proportionality of the House, but only to a limited degree). Seven seats are currently reserved for members elected on a separate Māori roll . However, Māori may choose to vote in and to run for the non-reserved seats, and several have entered Parliament in this way . </P> <P> The Cabinet, which is responsible to Parliament, exercises executive authority . (The Cabinet forms the practical expression of a formal body known as the Executive Council .) The Prime Minister, as the leader of the political party or coalition of parties holding or having the support of a majority of seats in the House of Representatives, leads the Cabinet . All Cabinet Ministers must be Members of Parliament (MPs) and are collectively responsible to it . The Prime Minister and all other ministers take office upon receiving a warrant by the Governor - General . Unlike many other countries, there is no requirement for a formal vote of approval by the legislature before they may assume office . </P> <P> New Zealand's judiciary is a hierarchy consisting of the Supreme Court of New Zealand, the Court of Appeal of New Zealand, the High Court of New Zealand, and the District Courts . These courts are all of general jurisdiction . There are several other courts of specialist jurisdiction, including the Employment Court, the Environment Court and the Māori Land Court, as well as the Family Court and the Youth Court, which operate as specialised divisions of the District Courts . There are also a number of specialised tribunals which operate in a judicial or quasi-judicial capacity, such as the Disputes Tribunal, the Tenancy Tribunal and the Waitangi Tribunal . </P> <P> New Zealand law has three principal sources: English common law; certain statutes of the United Kingdom Parliament enacted before 1947 (notably the Bill of Rights 1689); and statutes of the Parliament of New Zealand . In interpreting common law, there is a rebuttable presumption in support of uniformity with common law as interpreted in the United Kingdom and related jurisdictions . Non-uniformity arises where the New Zealand courts consider local conditions to warrant it or where the law has been codified by New Zealand statute . The maintenance of the Judicial Committee of the Privy Council in London as the final court of appeal and judges' practice of tending to follow British decisions, even though, technically, they are not bound by them, both bolstered this presumption . The Supreme Court of New Zealand, which was established by legislation in October 2003 and which replaced the Privy Council for future appeals, has continued to develop the presumption . </P>

Treaty of waitangi in the new zealand constitution