Constitution of Australia

The Constitution of Australia is the supreme law under which the Australian Commonwealth Government operates. It consists of several documents. The most important is the Constitution of the Commonwealth of Australia. The Constitution was approved in referendums held over 1898–1900 by the people of the Australian colonies, and the approved draft was enacted as a section of the Commonwealth of Australia Constitution Act 1900 (Imp), an Act of the Parliament of the United Kingdom.

Royal Assent was given by Queen Victoria on 9 July 1900, upon which date the Constitution became law. It came into force on 1 January 1901 by virtue of a proclamation issued by Queen Victoria on 17 September 1900, pursuant to section 3 of the Act. Even though the Constitution was originally given legal force by an Act of the United Kingdom parliament, the Australia Act 1986 removed the power of the United Kingdom parliament to change the Constitution as in force in Australia, and the Constitution can now only be changed in accordance with the prescribed referendum procedures.

Other pieces of legislation have constitutional significance for Australia. These are the Statute of Westminster, as adopted by the Commonwealth in the Statute of Westminster Adoption Act 1942, and the Australia Act 1986, which was passed in equivalent forms by the Parliaments of every Australian state, the United Kingdom, and the Australian Federal Parliament. The Statute of Westminster Adoption Act made Australia a de jure independent nation (though it had been de facto independent for some years before then), while the Australia Act severed the last remaining constitutional links between Australia and the United Kingdom. Even though the same person, Queen Elizabeth II, is the monarch of both countries, she acts in a distinct capacity as monarch of each.

Under Australia's common law system, the High Court of Australia and the Federal Court of Australia have the authority to interpret constitutional provisions. Their decisions determine the interpretation and application of the constitution.