Constitution of Australia

The Constitution of Australia (also known as the Commonwealth Constitution) is the fundamental law that governs the political structure of Australia. It is a written constitution, which establishes the country as a federation under a constitutional monarchy governed with a parliamentary system. Its eight chapters set down the structure and powers of the three constituent parts of the federal level of government: the Parliament, the Executive Government and the Judicature.

The Constitution was drafted between 1891 and 1898 at a series of conventions conducted by representatives of the six self-governing British colonies in Australia: New South Wales, Victoria, Queensland, Western Australia, South Australia and Tasmania. This final draft was then approved by each state in a series of referendums from 1898 to 1900. The agreed constitution was transmitted to London where, after some minor modifications, it was enacted as section 9 of the Commonwealth of Australia Constitution Act 1900, an act of the Parliament of the United Kingdom. It came into effect on 1 January 1901, at which point the six colonies became states within the new Commonwealth of Australia.

The Constitution is the primary, but not exclusive, source of Australian constitutional law; it operates alongside constitutional conventions, state constitutions, the Statute of Westminster 1931, the Australia Acts 1986, prerogative instruments and judicial interpretations of these laws by the High Court of Australia.

The document may only be amended by referendum, through the procedure set out in section 128. This requires a double majority: a nationwide majority as well as a majority of voters in a majority of states. Only eight of the 45 proposed amendments put to a referendum have passed. Proposals to amend the document to recognise Indigenous Australians and to become a republic are the subject of significant contemporary debate. The most recent referendum occurred on 14 October 2023, in which a proposed amendment to establish an Indigenous Voice to Parliament was rejected.

Political movements to federate the Australian colonies grew to prominence in the mid 19th century. Multiple motivations existed for increased political co-operation between the colonies; including a desire to regulate inter-colonial tariffs.

Tensions existed, however, between the larger colonies and the smaller ones, and in the degree to which each colony embraced protectionist policies. Those tensions and the outbreak of the American Civil War harmed the political case for federalism in the 1850s and 1860s.

In 1889 the Federal Council of Australasia was established. It arose out of a fear of the growing presence of German and French colonies in the Pacific, and a growing Australian identity. The council could legislate on certain subjects but did not have a permanent secretariat, an executive, or independent source of revenue. Perhaps most problematically New South Wales, the largest colony, did not join the body.

A series of conferences to discuss federalism was promoted by the premier of New South Wales Henry Parkes; the first held in 1890 at Melbourne, and another at Sydney in 1891. These conferences were attended by most colonial leaders.