Constitutional basis and appointment
The Prime Minister of Australia is appointed by the Governor-General of Australia under Section 64 of the Australian Constitution, which empowers the Governor-General, as the official representative of the Crown, to appoint government ministers of state on the advice of the Prime Minister and requires them to be members of the House of Representatives or the Senate, or become members within three months of the appointment. The Prime Minister and Treasurer are traditionally members of the House, but the Constitution does not have such a requirement. Before being sworn in as a Minister of State, a person must first be sworn in as a member of the Federal Executive Council if they are not already a member. Membership of the Federal Executive Council entitles the member to the style of The Honourable (usually abbreviated to The Hon) for life, barring exceptional circumstances. The senior members of the Executive Council constitute the Cabinet of Australia.
The Prime Minister is, like other ministers, normally sworn in by the Governor-General and then presented with the commission (letters patent) of office. When defeated in an election, or on resigning, the Prime Minister is said to "hand in the commission" and actually does so by returning it to the Governor-General. In the event of a Prime Minister dying in office, or becoming incapacitated, or for other reasons, the Governor-General can terminate the commission. Ministers hold office "during the pleasure of the Governor-General" (s. 64 of the Constitution of Australia), so theoretically, the Governor-General can dismiss a minister at any time, by notifying them in writing of the termination of their commission; however, their power to do so except on the advice of the Prime Minister is heavily circumscribed by convention.
According to convention, the Prime Minister is the leader of the majority party or largest party in a coalition of parties in the House of Representatives which holds the confidence of the House. Some commentators argue that the Governor-General may also dismiss a Prime Minister who is unable to pass the government's supply bill through both houses of parliament, including the Australian Senate, where the government doesn't normally command the majority, as happened in the 1975 constitutional crisis. Other commentators argue that the Governor General acted improperly in 1975 as Whitlam still retained the confidence of the House of Representatives, and there are no generally accepted conventions to guide the use of the Governor General's reserve powers in this circumstance. However, there is no constitutional requirement that the Prime Minister sit in the House of Representatives, or even be a member of the federal parliament (subject to a constitutionally prescribed limit of three months), though by convention this is always the case. The only case where a member of the Senate was appointed Prime Minister was John Gorton, who subsequently resigned his Senate position and was elected as a member of the House of Representatives.
Despite the importance of the office of Prime Minister, the Constitution does not mention the office by name. The conventions of the Westminster system were thought to be sufficiently entrenched in Australia by the authors of the Constitution that it was deemed unnecessary to detail them. The formal title of the portfolio has always been simply "Prime Minister", except for the period of the Fourth Deakin Ministry (June 1909 to April 1910), when it was known as "Prime Minister (without portfolio)".
If a government cannot get its appropriation (budget) legislation passed by the House of Representatives, or the House passes a vote of "no confidence" in the government, the Prime Minister is bound by convention to immediately advise the Governor-General to dissolve the House of Representatives and hold a fresh election.
Following a resignation in other circumstances or the death of a Prime Minister, the governor-general generally appoints the Deputy Prime Minister as the new Prime Minister, until or if such time as the governing party or senior coalition party elects an alternative party leader. This has resulted in the party leaders from the Country Party (now named National Party) being appointed as Prime Minister, despite being the smaller party of their coalition. This occurred when Earle Page became caretaker Prime Minister following the death of Joseph Lyons in 1939, and when John McEwen became caretaker Prime Minister following the disappearance of Harold Holt in 1967. However in 1941, Arthur Fadden became the leader of the Coalition and subsequently Prime Minister by the agreement of both coalition parties, despite being the leader of the smaller party in coalition, following the resignation of UAP leader Robert Menzies.
Excluding the brief transition periods during changes of government or leadership elections, there have only been a handful of cases where someone other than the leader of the majority party in the House of Representatives was Prime Minister:
- Federation occurred on 1 January 1901, but elections for the first parliament were not scheduled until late March. In the interim, an unelected caretaker government was necessary. In what is now known as the Hopetoun Blunder, the governor-general, Lord Hopetoun, invited Sir William Lyne, the premier of the most populous state, New South Wales, to form a government. Lyne was unable to do so and returned his commission in favour of Edmund Barton, who became the first Prime Minister and led the inaugural government into and beyond the election.
- During the second parliament, three parties (Free Trade, Protectionist and Labor) had roughly equal representation in the House of Representatives. The leaders of the three parties, Alfred Deakin, George Reid and Chris Watson each served as Prime Minister before losing a vote of confidence.
- As a result of the Labor Party's split over conscription, Billy Hughes and his supporters were expelled from the Labor Party in November 1916. He subsequently continued on as prime minister at the head of the new National Labor Party, which had only 14 members out of a total of 75 in the House of Representatives. The Commonwealth Liberal Party – despite still forming the Official Opposition – provided confidence and supply until February 1917, when the two parties agree to merge and form the Nationalist Party.
- During the 1975 constitutional crisis, on 11 November 1975, the governor-general, Sir John Kerr, dismissed the Labor Party's Gough Whitlam as Prime Minister. Despite Labor holding a majority in the House of Representatives, Kerr appointed the Leader of the Opposition, Liberal leader Malcolm Fraser as caretaker Prime Minister, conditional on the passage of the Whitlam government's Supply bills through the Senate and the calling of an election for both houses of parliament. Fraser accepted these terms and immediately advised a double dissolution. An election was called for 13 December, which the Liberal Party won in its own right (although the Liberals governed in a coalition with the Country Party).