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Australia employs a federal system of government. The national government is the Australian federal government, headed by the Queen, who is represented in Australia by the Governor-General of Australia, though ordinarily actual political power is wielded by the Prime Minister of Australia under the Westminster system.
Australia is further divided into states and territories. These states and territories are mostly self-governed, and largely employ a similar Westminster system of government. Under the Constitution of Australia, the states retain their sovereign powers except where power has been assigned to the federal government in accordance with the Constitution, or referred to the government by the states by legislation. Territories, on the other hand, are given their autonomous powers by the federal government through legislation.
The federal government and most states and territories possess a judiciary which is constitutionally separate from the legislature and executive branches of government. Each of these is a separate jurisdiction, though current jurisprudence in Australia suggests that there is only one common law of Australia, the ultimate authority of which is the High Court of Australia.
The third level of government are local governments. These are creations of the states and territories under each of their laws. The divisions are called local government areas (lgas). A number of titles are used by local governments, including "cities", "shires", "municipalities" and "councils".
Externally, though Australia shares the same monarch as the United Kingdom and a number of other realms, it is constitutionally separate. Since the passing and subsequent adoption of the Statute of Westminster in 1942, the Australian federal government has been legally separate from the (then) Imperial government at Westminster, and Australia as a whole has not been subject to laws passed by the Imperial parliament. Since the passing of the Australia Act 1986, Australia, and its states and territories, have become legally completely separate and no longer subject to the authority of any part of the government of the United Kingdom. However, Australia still retains a symbolic reminder of its former relationship with the United Kingdom and other realms through its membership in the Commonwealth of Nations.
Prior to 1901, Australia was a collection of colonies answerable to the United Kingdom. The oldest among these, New South Wales, had been established in 1788. With Federation in 1901, a new entity, the Commonwealth of Australia, was created by an Act of the British Parliament. The system of government for the Commonwealth was a federation, with a federal, Commonwealth government being the national government. The former colonies were converted into States, sub-national sovereign entities whose governments retained plenary power within their own territories, except where power has been assigned to the Commonwealth by the Constitution. Some of the non-integral territories of the former colonies, such as the Northern Territory of South Australia, were handed over to the Commonwealth. The Constitution also provided for the power of the federal government to create further territories in future.
Federal government 
For the operations of Australia's federal government, see
- Government of Australia
- Queen of Australia
- Governor-General of Australia
- Prime Minister of Australia
- Parliament of Australia
- High Court of Australia
- Australian electoral system
State and territory governments 
For the operations of the governments of Australia's states and territories, see
- Governors of the Australian states
- Parliaments of the Australian states and territories
- Premiers of the Australian states
- Government of New South Wales
- Government of Victoria
- Government of Queensland
- Government of Western Australia
- Government of South Australia
- Government of Tasmania
- Government of the Australian Capital Territory
- Government of the Northern Territory
Local governments 
For local government see