This article describes the federal government of Australia. See Australian governments for other jurisdictions.
The Commonwealth of Australia is a constitutional monarchy, a federation, and a parliamentary democracy. The Commonwealth of Australia was formed in 1901 as a result of an agreement between what were previously six self-governing British colonies. The terms of this agreement are embodied in the Australian Constitution, which was drawn up at a Constitutional Convention and ratified by the people of the colonies at referendums. The structure of the Australian Government may be examined in light of two distinct concepts, namely federalism and the separation of powers into legislative, executive and judiciary branches of government. Separation of powers is implied from the structure of the Constitution which breaks down the branches of government into separate chapters.

Separation of power

Main article: Parliament of Australia Legislature

Executive
The Australian Constitution dates from 1900, when the Dominions of the British Empire were not sovereign states, and does not use the term "head of state". In practice, the role of head of state of Australia is divided between two people, the Queen of Australia and the Governor-General of Australia, who is appointed by the Queen on the advice of the Prime Minister of Australia. Though in many respects the Governor-General is the Queen's representative, and exercises various constitutional powers in her name, he is also independently vested with many important constitutional powers by the Constitution.
The Queen, or Sovereign, of Australia, currently Queen Elizabeth II, is also the Sovereign of fifteen other Commonwealth Realms including the United Kingdom. Like the other Dominions, Australia gained legislative independence from the Parliament of the United Kingdom by virtue of the Statute of Westminster 1931, which was adopted in Australia in 1942 with retrospective effect from 3 September 1939. By the Royal Style and Titles Act 1953, the Australian Parliament gave the Queen the title Queen of Australia, and in 1973 removed from the Queen's Australian style and titles any reference to her status as Queen of the United Kingdom and Defender of the Faith.
Section 61 of the Constitution provides that 'The executive power of the Commonwealth is vested in the Queen and is exercisable by the Governor‑General as the Queen's representative, and extends to the execution and maintenance of this Constitution, and of the laws of the Commonwealth'. Section 2 of the Australian Constitution provides that a Governor-General shall represent the Queen in Australia. In practice, the Governor-General carries out all the functions usually performed by a head of state without reference to the Queen.
The question of whether the Queen is Australia's head of state became a political one during the 1999 Australian republic referendum, when opponents of the move to make Australia a republic claimed that Australia already had an Australian as head of state in the person of the Governor-General, who since 1965 has invariably been an Australian citizen. The current Governor-General, Major General Michael Jeffery, said in 2004: "Her Majesty is Australia's head of state but I am her representative and to all intents and purposes I carry out the full role." However, in 2005, he declined to name the Queen as head of state, instead saying in response to a direct question, "The Queen is the Monarch and I represent her, and I carry out all the functions of Head of State." See De facto head of state.
Under the conventions of the Westminster system the Governor-General's powers are almost always exercised on the advice of the Prime Minister or other ministers. The Governor-General retains reserve powers similar to those possessed by the Queen in the United Kingdom. These are rarely exercised, but during the Australian constitutional crisis of 1975 Governor-General Sir John Kerr used them independently of the Queen and the Prime Minister.
Australia has periodically experienced movements seeking to end the monarchy. In a 1999 referendum, the Australian people voted on a proposal to change the Constitution. The proposal would have removed references to the Queen from the Constitution and replaced the Governor-General with a President nominated by the Prime Minister, but subject to the approval of a two-thirds majority of both Houses of the Parliament. The proposal was defeated. The Australian Republican Movement continues to campaign for an end to the monarchy in Australia, opposed by Australians for Constitutional Monarchy.
For more information, see constitutional history of Australia and Australian republicanism.

Head of state

Main article: Federal Executive Council Executive Council

Main article: Cabinet of Australia Cabinet

Main article: List of Australian Government Departments Judiciary
^  Prior to 1931, the junior status of dominions was shown in the fact that it was British ministers who advised the King, with dominion ministers, if they met the King at all, escorted by the constitutionally superior British minister. After 1931 all dominion ministers met the King as His ministers as of right, equal in Commonwealth status to Britain's ministers, meaning that there was no longer either a requirement for, or an acceptance of , the presence of British ministers. The first state to exercise this both symbolic and real independence was the Irish Free State. Australia and other dominions soon followed.