The Australian Constitution may only be changed by referendum.
Unlike some other countries and the Australian states, the Constitution cannot be changed by the Commonwealth Parliament. However, a proposed change to the Constitution must originate in the Parliament.
Section 128 of the Constitution sets out the procedure for this:
A bill must be passed by an absolute majority of both houses of parliament. In the event of disagreement between the houses over the referendum proposal, and after the passage of three months that disagreement remains, the referendum as originally proposed in either house may proceed.
Between two and six months after approval by the Parliament, the proposed alteration must be submitted to voters in each State and Territory.
A majority of electors nationwide, plus a majority of voters in a majority of States (4/6), must approve the referendum. This is known as the “double majority”.
After passage by the voters, the proposed alteration to the Constitution requires the royal assent. This will always be granted.
There have been 45 referendums submitted to the people since 1901. Of these, only 8 have been successful.
No referendum has succeeded since 1977.