Commonwealth Electoral Act 1918

The Commonwealth Electoral Act 1918 replaced the Commonwealth Franchise Act 1902 which defined who was allowed to vote in Australian federal elections. The Commonwealth Electoral Act comprehensively rewrote the Franchise Act and introduced instant-runoff voting, known in Australia as Preferential Voting. Preferential voting, which was pioneered by Queensland in 1892, replaced first-past-the-post voting.

The Single Transferable Vote was introduced for the Senate in 1949, and the qualifying age for voting was lowered to 18 in 1973. Indigenous Australians were granted the right to vote at a federal level in 1962.

In 1984 the Australian House of Representatives was expanded by 24 seats and the Australian Senate by 12 seats. A Senate ticket voting system was introduced and also the grace period after an election is called before the electoral rolls are closed was extended to seven days.