How does a referendum pass?

A federal referendum passes in Australia only if it secures a double majority: a national majority of voters across Australia (more than 50 per cent Yes), plus a majority of voters in at least four of the six states (with at least four states recording more than 50 per cent Yes individually). Voters in the two mainland territories count toward the national total but not toward the state-by-state count.

The double majority is set by section 128 of the Australian Constitution. The rule was designed to ensure that constitutional change has broad support across the country, not just in the most populous states. A proposal that achieved 51 per cent nationally by drawing 70 per cent in New South Wales and Victoria but less than 50 per cent in the other four states would fail under the double majority, preserving the federal balance between large and small states.

Several historical scenarios illustrate the rule. The 1967 referendum recognising Aboriginal people in the Constitution passed with 90.77 per cent nationally and majorities in all six states, the highest Yes vote in Australian referendum history. The 1977 referendum setting age 70 for federal judges passed with 80.10 per cent nationally and in all six states. The 1944 fourteen-powers referendum (proposing to give the Commonwealth a wide range of post-war reconstruction powers) achieved a national majority but failed in three states, so was defeated. The 1999 republic referendum received 45.13 per cent nationally and was defeated in every state. The 2023 Voice referendum received 39.94 per cent nationally and was carried in no state.

Two-tier scrutiny shapes the campaign. Yes and No cases are presented in the Yes/No pamphlet distributed to every Australian household by the Australian Electoral Commission. Authorised campaign committees of parliamentarians (in equal numbers from those who voted Yes and those who voted No in the parliamentary debate) draft the two cases. The AEC also runs voter education advising Australians of the date, the voting requirements, and the process. Compulsory voting applies, with fines for non-voters. Referendums use preferential or single-vote ballot papers depending on the number of questions, with the 2023 Voice referendum using a single Yes-or-No question.