The Constitution


Contributor: Joseph A Barravecchio

The Constitution is the fundamental rules by which Australia is governed. The Constitution is Australia’s supreme law and may only be amended by referendum. The Constitution outlines the basis for relations between the Commonwealth and the States of Australia.

The Governor-General and the governors

The head of state in Australia is the Queen of Australia, who is also the Queen of the United Kingdom and the head of the Commonwealth of Nations (formerly called the British Commonwealth). The Governor-General and state governors are her representatives. They are appointed by the Queen, but she does so on the basis of advice provided by the relevant head of government (i.e. the prime minister or premier).

The Commonwealth and state constitutions appear to provide extensive powers to the Queen’s representatives. However, those powers are exercised in accordance with ministerial advice (except in relation to a very narrow range of issues known as the “reserve powers”).


The federal parliament and the parliament of each state (other than Queensland) is made up of two houses. All Commonwealth and state legislation must be passed by each house of parliament and be approved by the Queen’s representative before becoming a law.

The extent of the power of Australian parliaments to make laws is detailed in the Commonwealth of Australia Constitution Act 1900 (Cth) (“Commonwealth Constitution”) and state constitutions, for example the Constitution Act 1975 (Vic). The Commonwealth legislative powers are listed in the Commonwealth Constitution and most are not exclusive to the Commonwealth. The Commonwealth legislative powers include defence, taxation, marriage, trade and commerce, immigration and lighthouses. The states do not have a list of legislative powers, but their constitutions provide the legislative power to make laws “for the peace, order and good government of the state”. This is a broad power to make laws about all matters relating to the state.

Therefore, there is an overlap between Commonwealth and state legislative powers, which can lead to inconsistent Commonwealth and state laws. If a state law is inconsistent with a Commonwealth law, section 109 of the Commonwealth Constitution states that the Commonwealth law prevails. The state law is inoperative while the inconsistency exists.

If a parliament makes a law that is outside the powers set out in the relevant constitution, then the validity of that law can be challenged. Sections, whole parts, or a complete Act can be declared invalid if the courts find it unconstitutional; that is, the relevant constitution did not give parliament the power to make that law.

There are also some implied restrictions on legislative power that the courts have derived from the terms of the Commonwealth Constitution; the most significant being the implied freedom of political communication.

Disputes about interpreting the Commonwealth Constitution can only be resolved in the High Court.

Changing the constitution

The Commonwealth Constitution is “entrenched” and can only be changed by the successful passage of a referendum by a majority of voters and a majority of voters in a majority of states (s 128 Commonwealth Constitution).

However, most state constitutions are normal Acts of parliament, although some states have a form of entrenchment for some of the constitutional provisions. Of the states, Victoria has the greatest degree of entrenchment; many of the provisions in Victoria’s constitutions are only alterable by either a referendum or a 60 per cent majority in both houses of parliament (s 18 Constitution Act 1975 (Vic)).