Australia's constitution never mentions its prime minister
Australia's most powerful political job does not appear anywhere in its constitution. The drafters assumed Westminster conventions were so firmly rooted that writing them down was unnecessary, so the prime minister's powers rest on unwritten custom, including the rule that the job goes to whoever commands the confidence of the lower house.
Before Federation, premier and prime minister were used interchangeably for colonial leaders. The office got off to an awkward start in what became known as the Hopetoun Blunder. Needing a caretaker before the first elections, Governor-General Lord Hopetoun asked William Lyne, premier of New South Wales, to form a government, but no politician would serve in his cabinet. Edmund Barton was commissioned instead and became the first prime minister on 1 January 1901.
Formally the governor-general appoints the prime minister, but convention requires choosing the person who can hold the confidence of the House of Representatives, normally the leader of the majority party or coalition. The prime minister must also sit in that house. The only senator ever appointed, John Gorton, quickly resigned from the Senate and won the lower-house seat of Higgins. There are no term limits, and since the 2007 election, leaders have been toppled by their own party colleagues four times, against just two changes of power at elections.
Unexpected vacancies have produced odd results. When a prime minister dies or leaves suddenly, the deputy usually steps in until the governing party picks a leader, which is how Country Party leaders became caretaker prime ministers after Joseph Lyons died in 1939 and after Harold Holt disappeared in 1967. In the second parliament, three roughly equal parties meant Alfred Deakin, George Reid and Chris Watson each held the job before losing a confidence vote.
The unwritten rules were tested hardest in 1975, when Governor-General Sir John Kerr dismissed Gough Whitlam's government after the Senate held up its budget. Thirty-one people have held the office, thirty men and one woman. Robert Menzies served over 18 years, while Frank Forde lasted a single week.
Source: Prime Minister of Australia
