What is Federation in Australian history?

Federation, viewed as a legal and constitutional event, is the creation on 1 January 1901 of a new federal polity called the Commonwealth of Australia by the operation of the Commonwealth of Australia Constitution Act 1900 (Imp), an Act of the United Kingdom Parliament. The Act contains the Australian Constitution as its ninth clause and supplies the foundation legal document that has governed the country ever since.

The Constitution distributes power between two layers of government. Section 51 lists the 39 enumerated heads of Commonwealth legislative power, covering matters such as trade and commerce, taxation, defence, external affairs, currency, postal services, banking, insurance, marriage, and corporations. Section 52 sets out exclusive Commonwealth powers. Section 109 makes a valid Commonwealth law prevail over an inconsistent state law to the extent of the inconsistency, and section 106 keeps the constitutions of the former colonies in force as state constitutions, converting the colonies into states of the new Commonwealth. Section 92 guarantees absolutely free interstate trade and intercourse, which the High Court has used to strike down state and federal laws that burden interstate movement.

The Constitution also creates the institutions of the new Commonwealth. Section 1 vests legislative power in a federal Parliament made up of the King (through the Governor-General), the Senate, and the House of Representatives. Sections 7 and 24 prescribe the composition of the two chambers: a Senate of equal state representation and a House proportionate to population, with the House about twice the size of the Senate. Section 61 vests executive power in the Crown and authorises its exercise by the Governor-General. Chapter III, beginning at section 71, vests federal judicial power in the High Court of Australia and any other federal courts Parliament creates. Schedule 1 supplies the oath and affirmation for parliamentarians.

Several constitutional rules frame how the federation can change. Section 128 makes the Constitution amendable only by referendum: a Bill must pass both Houses of Parliament (or one House twice with a deadlock), then be put to a national vote requiring a national majority of voters plus majorities in a majority of states (four out of six). Out of 45 proposals put to referendum since 1901, only eight have succeeded, the most recent failure being the 14 October 2023 Voice referendum. Sections 121 and 122 allow new states and territories to be admitted. The federal capital was authorised by section 125 and located at Canberra by the Seat of Government Act 1908. The Australia Acts of 1986 (passed by the UK Parliament and by the Commonwealth and state parliaments) severed the remaining legal links to the United Kingdom, leaving the Constitution as a purely Australian legal document amendable only by Australian voters.