The Australian Constitution was drafted at two conventions in the 1890s and approved by the people of the colonies of Australia at a series of referendums between 1898 and 1900. It was passed as an Act of the British Parliament and received Royal Assent from Queen Victoria on 9 July 1900.

When the Commonwealth of Australia Constitution Act commenced on 1 January 1901 it established the Australian Government and gave the Australian Parliament the power to make laws on certain matters (mostly listed in sections 51 and 52). The six colonies became Australia's six states, and have the power to make laws on a much wider range of matters. However, if a valid Commonwealth law is inconsistent with the law of a State, then the Commonwealth law overrides the State law. The Constitution also establishes the Queen as a part of the Parliament (section 1), and allows her powers to be exercised by the Governor-General (section 61).