2.2 The Prime Minister is appointed by warrant by the Governor-General. In making this appointment, constitutional convention requires the Governor-General to:
- act on the outcome of the electoral process and subsequent discussions between political parties. These discussions ascertain which party, or group of parties, appears able to command the confidence of the House of Representatives (expressed through public statements) and therefore has a mandate to govern the country; and
- act on the outcome of the political process by which the person who will lead the government as Prime Minister is identified.
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 significant 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.
2.6 The Prime Minister alone has the right to advise the Governor-General to:
- appoint, revoke the appointment of, dismiss, or accept the resignation of Ministers;
- dissolve Parliament and call a general election.
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 agencies, 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.
2.10 The Prime Minister has an important role in maintaining and coordinating the government by overseeing the government's general policy direction.
2.11 The Prime Minister customarily has overall ministerial responsibility for national security and intelligence matters, and for Ministerial Services, and may also hold other portfolios.
2.12 The Prime Minister's ministerial and executive duties are separate from the leadership role in the Prime Minister's own political party and caucus.