Like the United States and unlike Britain, Australia has a written constitution. The Australian Constitution defines the responsibilities of the federal government, which include foreign relations, trade, defence and immigration. Governments of states and territories are responsible for all matters not assigned to the Commonwealth, and they too adhere to the principles of responsible government. In the states, the Queen is represented by a Governor for each state.
The High Court of Australia arbitrates on disputes between the Commonwealth and the states. Many of the court’s decisions have expanded the constitutional powers and responsibilities of the federal government.
The Australian Constitution can be amended only with the approval of the electorate through a national referendum in which all adults on the electoral roll must participate. A bill containing the amendment must first be passed by both houses of parliament or, in certain limited circumstances, by only one house of parliament. Any constitutional changes must be approved by a double majority—a national majority of electors as well as a majority of electors in a majority of the states (at least four of the six). Where any state or states are particularly affected by the subject of the referendum, a majority of voters in those states must also agree to the change. This is often referred to as the ‘triple majority’ rule.
The double majority provision makes alterations to the Constitution difficult. Since federation in 1901, only eight out of 44 proposals to amend the Constitution have been approved. Voters are generally reluctant to support what they perceive as increases in the power of the federal government. States and territories may also hold referendums.