[This article was first published on 18 April 2023 and was updated on 4 July 2023 following passage of the Constitution Alteration (Aboriginal and Torres Strait Islander Voice) 2023 through the Parliament.]

The rules for altering the Australian Constitution are provided by section 128 of the Constitution. Before a referendum can be held, a proposed law for the alteration of the Constitution must first be passed by the Australian Parliament.

While there are some unique features of Constitution alteration bills, which are explained in this article, they are otherwise like any other bill.

Content of Constitution alteration bills

Voice proposal – question to be put to the people at the referendum – Long title:

Voice proposal – proposed amendment to the Constitution – Schedule 1:

Voice proposal – On 30 March 2023, the Attorney-General introduced the Constitution Alteration (Aboriginal and Torres Strait Islander Voice) 2023 into the House of Representatives.

(see Votes and Proceedings, 30/03/2023, p. 649).

Voice proposal – On 30 March 2023, both Houses agreed to the establishment of a joint select committee to inquire into and report on the provisions of the bill (for the Senate resolution, see here). The committee presented its advisory report on the bill on 12 May 2023. On the presentation of the committee’s report, the committee ceased to exist.

Information about the committee and its inquiry can be viewed on the committee’s webpage.

The wording of the proposed referendum question and the proposed amendment to the Constitution are contained in the bill.

The proposed question to be put to the people for approval at a referendum (i.e. the question on the ballot paper) is the Constitution alteration as expressed in the long title of the bill.

The ballot paper requirements are set out in Schedule 1 to the Referendum (Machinery Provisions) Act 1984.

The proposed amendment to the Constitution is included in the text of the bill. These days it appears in a schedule to the bill.

Passage through the Parliament

Initiation

A bill to alter the Constitution may originate in either House although, like ordinary bills, most have originated in the House of Representatives.

Only 3 of the 44 Constitution alteration proposals that have been submitted to the voters at a referendum originated in the Senate.

One nuance to bills containing Constitution alteration proposals is that the short title does not contain the word 'Act', nor is 'Bill' included in its title as it progresses through Parliament. This is because '[w]hile the proposed law is converted to an 'Act' after approval at a referendum and at the point of assent, in a technical sense it is strictly a constitution alteration proposal and its short title remains unchanged': House of Representatives Practice, p. 27.

Committee inquiry

As with other bills, a Constitution alteration bill can be the subject of an inquiry by a parliamentary committee.

Requirement for an absolute majority

Section 128 of the Constitution requires that a bill to alter the Constitution must be passed by an absolute majority of each House (i.e. a majority of the whole number of legislators in each House—currently 39 senators and 76 members of the House of Representatives). This is different to ordinary bills where only a simple majority is required (i.e. a majority of legislators actually voting).

The procedures of the Senate reflect this Constitutional requirement by providing that if a Constitution alteration bill is not agreed by an absolute majority at the third reading it will be laid aside and cannot be revived during the same session (Senate standing order 135 and Odgers' Australian Senate Practice, p. 345).

As an example, on 15 May 2003, 36 senators voted in favour of the Constitution Alteration (Right to Stand for Parliament—Qualification of Members and Candidates) 1998, with 26 senators voting against. For an ordinary bill a simple majority such as this would mean that the bill passes the Senate, however because an absolute majority of 39 votes was required the bill was laid aside.

In order to demonstrate that a Constitution alteration bill has been passed by an absolute majority, the names of the senators voting for the bill at the third reading are recorded in the Journals of the Senate. The bells are rung and votes are recorded as they are in a division, even if no division is called.

Where a Constitution alteration bill has been passed by the Senate with an amendment to which the House disagrees, a motion that the Senate does not to insist on its amendment must also be adopted by an absolute majority. A motion to insist on its amendment, however, does not require an absolute majority, as it does not alter the bill as passed by the Senate.

All other stages of the passage of the bill — first and second reading, voting on amendments in the Committee of the Whole stage and any procedural votes — require a simple majority.

The House of Representatives has similar requirements, see House of Representatives Practice, p. 385.

Passage by a single House

In cases of disagreement between the Houses, section 128 of the Constitution provides for the possibility of a Constitutional alteration proposal proceeding to a referendum where only one House has passed the bill and the other House has rejected it, failed to pass it or passed it with amendments unacceptable to the originating House. If, after an interval of 3 months the originating House again passes the bill with or without any amendment which has been made or agreed to by the other House, and the other House rejects or fails to pass it or passes it with any amendment to which the originating House will not agree, the Governor-General may submit to the voters the proposed law as passed by the originating House (either with or without any amendments subsequently agreed to by both Houses).

The only occasion where this has occurred was in 1974, when 4 proposals that had only passed the House of Representatives were submitted to the voters. None of the proposals were successful in the ensuing referendum.

Although the Constitution is clear that a proposal originating in either House may proceed in this way, as the Government has control of the House of Representatives and advises the Governor-General on executive matters, a proposal passed only by the Senate without approval by the Government in the House of Representatives is unlikely to be submitted to a referendum by the Governor-General (for further see Odgers' Australian Senate Practice, p. 346).

For example, in June 1914, after the Senate had forwarded 6 Constitution alterations, to which the House had not agreed, to the Governor-General to be submitted to the voters, the Governor-General replied:

… I have consulted my Ministers, who by the express terms of the Constitution are appointed to advise me in the government of the Commonwealth, and have submitted the Senate's Address and accompanying documents to them.

They, having taken the matter into their consideration, are unable to advise me to comply with the request contained in the Address of the Senate. I accept their advice, and am unable to grant the request of the Senate (Journals of the Senate, No. 23, 24 June 1914, p. 98).

Proposals not proceeded with

Not all Constitution alteration proposals that have passed both Houses have proceeded to a referendum, despite the wording of section 128 which provides that a proposal passed by both Houses 'shall be submitted' to the voters. There have been 4 occasions where alteration proposals passed by the Parliament with the prescribed majority have not been put to a referendum, on the advice of the Government, in 1915, 1965, 1983 and 2013. The most recent example is the Constitution Alteration (Local Government) 2013, which was passed by both Houses (without amendment) in June 2013 but was not subsequently put to a referendum. For details of these examples see Odgers' Australian Senate Practice, p. 345 and House of Representatives Practice, p. 28.

Referendums

Section 128 of the Constitution sets the time frame for when an alteration proposal is to be put to the voters at a referendum as '… not less than two nor more than six months after its passage through both Houses…'.

Section 128 also provides that '[w]hen a proposed law is submitted to the electors the vote shall be taken in such a manner as the Parliament prescribes'. The Parliament has enacted the Referendum (Machinery Provisions) Act 1984 (Machinery Provisions Act) for this purpose. A bill to amend that Act, the Referendum (Machinery Provisions) Amendment Bill 2022 passed the Parliament on 23 March 2023, to update the Act to '… ensure a consistent voter experience across elections and referendums'. See the explanatory memorandum to the bill for further detail.

Yes/No case pamphlet

Once a Constitution alteration proposal is passed by the Parliament, the Machinery Provisions Act provides that a pamphlet detailing the arguments in favour of and against the proposal is to be distributed to each household by the Australian Electoral Commission (AEC) if each argument is authorised by a majority of the parliamentarians who voted for or against the proposal in the Parliament. The authorised arguments must be submitted to the AEC within 4 weeks after the passage of the proposal and are presented in an essay form of not more than 2,000 words each. The AEC therefore has no involvement in the development of the Yes or No arguments and is only obliged to distribute each argument if it is submitted on time and is appropriated authorised.

Voting

Source: Australian Electoral Commission

All Australians on the electoral roll are qualified to vote and, as with elections, voting is compulsory for citizens over the age of 18. Like elections, referendums must be held on a Saturday. Although referendums can be held on any Saturday, 8 out of the 19 referendums held have been scheduled for the same day as a federal election.

As noted above, the long title of the bill forms the basis of the question to the voter on the ballot paper, as demonstrated in the 1999 republic example shown to the left.

The result

In order to be successful, a referendum must be supported by a 'double majority'. This means that a majority of voters in a majority of the states (4 or more) and a national majority of all voters must approve of the proposal. Voters in the Australian Capital Territory and the Northern Territory are counted towards the national majority, but as they are not states do not count towards the states' majority.

If the required double majority is attained, the proposal is presented to the Governor-General for Royal Assent, and the Constitution is then amended accordingly.

More information

• Odgers' Australian Senate Practice (14th ed.), Chapter 12, pp. 344-346
• House of Representatives Practice (7th ed.), Constitution Alteration, pp. 26-34 and pp. 385-386
• Parliamentary Education Office, The Australian Constitution in focus    
• Parliamentary Library, Research Paper, Constitutional referendums in Australia: a quick guide
• Australian Electoral Commission, Referendums