Australian referendum, 1977 (Senate Casual Vacancies)

The referendum of 21 May 1977 approved an amendment to the Australian constitution concerning the filling of casual vacancies in the Senate. Technically it was a vote on the Constitution Alteration (Senate Casual Vacancies) 1977 which, after being approved in the referendum, became law on 29 July of the same year.

Prior to the amendment:

The amendment changed this procedure by providing that:

Its intended purpose was to prevent major changes in the balance of power in the senate in the middle of a parliamentary term, but as it did not provide any time limit within which the appointment had to be made, the state legislature remained free to decline to fill the vacancy. As Section 11 of the Constitution permits the Senate to carry on despite the failure to fill any vacancy, the amendment did not completely solve the problem.

On the same day as the vote on the casual vacancies amendment, four other questions were also put to the electorate. These concerned the:

The casual vacancies amendment came about as part of the political fallout from the Australian constitutional crisis of 1975. In the aftermath of this crisis, four amendments were recommended by sessions of the Australian Constitutional Convention, including one that would change the procedure for appointing replacement senators. All four were put to voters on 21 May 1977, and all were passed except a proposal for simultaneous elections to the House of Representatives and Senate.

The casual vacancies proposal arose out of the 1975 controversy over the appointment of independent Cleaver Bunton (New South Wales) and anti-Whitlam Australian Labor Party member Albert Field (Queensland) to fill Senate seats formerly held by ALP senators. The appointments ran counter to a longstanding convention that when a Senate seat became open due to a casual vacancy, the state parliament would appoint a replacement recommended by the former senator's party.

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