2.2 The Prime Minister is appointed by warrant by the Governor-General. In making this appointment, constitutional convention requires the Governor-General to:
2.3 The Prime Minister is the head of the government. The functions and powers of the Prime Minister have evolved over time. There is no statutory provision that constitutes the office of Prime Minister or defines its role.
2.4 The Prime Minister has several key constitutional roles. The Prime Minister is the principal adviser to the Sovereign and to the Sovereign's representative, the Governor-General, as long as the government commands the confidence of the House, and the Prime Minister maintains support as the leader of that government.
2.5 By constitutional convention, formal communication with the Sovereign is a matter for the Prime Minister. The Prime Minister advises the Sovereign on substantive matters; for example, the appointment of a new Governor-General, amendments to the Letters Patent Constituting the Office of Governor-General of New Zealand 1983 (the Letters Patent), and the conferment of royal honours.
2.7 The Prime Minister is also the head of executive government. This role includes the task of forming and maintaining a government, which, in a proportional representation system, will often involve working with other parties. The Prime Minister determines portfolio allocations and ministerial rankings, taking into account practical and political considerations.
2.8 The Prime Minister determines the title and scope of each portfolio - that is, the portfolio's area of operation, the legislation administered within the portfolio; the department(s), Crown entities, and other organisations reporting within the portfolio; and (where necessary) the relevant Vote(s) or appropriations within Votes.
2.9 As the chair of Cabinet, the Prime Minister approves the agenda, leads the meetings, and is the final arbiter of Cabinet procedure. The Prime Minister determines the terms of reference and membership of Cabinet committees.
2.11 The Prime Minister customarily is the Minister in charge of the Security Intelligence Service and Minister responsible for the Government Communications Security Bureau, and may also hold other portfolios.