Why is a referendum required to change the Australian Constitution?

Answer

Section 128 of the Australian Constitution requires that for any change to the Australian Constitution a referendum of the people is required. This referendum is based on obtaining a nationwide majority of 50% +1 together with a majority vote in a majority of the States which means that a referendum must also obtain a majority in four of the six states.

This ensures that politicians cannot, by themselves, amend the Constitution but that this can only be done by a vote of the people.