Separation of powers: Parliament, Executive and Judiciary

The principle of the separation of powers distributes the power to govern between the Parliament, the Executive and the Judiciary. This fact sheet examines the role of each group and the related principle of responsible government.

The Australian Constitution is the set of rules by which Australia is run. The first 3 chapters of the Constitution define 3 mostly separate groups—the Parliament, the Executive and the Judiciary—and the roles they play in the governing of Australia. The power to make and manage Australian law is divided between these 3 groups. This division is based on the principle of the 'separation of powers'.

Under this principle, the power to govern should be distributed between the Parliament, the Executive and the Judiciary to avoid any group having all the power. Each group should work within defined areas of responsibility to keep a check on the actions of the others.

Separation of roles





The Parliament makes and amends the law

Parliament (also referred to as the Legislature) is made up of the King (represented by the Governor-General), the Senate and the House of Representatives


The Executive puts the law into action

The Executive is made up of the King (represented by the Governor-General), Prime Minister and ministers


The Judiciary makes judgements about the law

The Judiciary is made up of the High Court of Australia and other federal courts

Exceptions to the principle

Australia does not have a complete separation of powers because some of the roles of the Parliament, the Executive and the Judiciary overlap. For example, the Prime Minister and ministers are part of the Executive and the Parliament. High Court judges, the Prime Minister and ministers are officially appointed by the Governor-General, who is part of the Parliament and the Executive.

The role of the Governor-General

Section 61 of the Constitution states that ‘the executive power of the Commonwealth is vested in the Queen and is exercisable by the Governor-General as the Queen’s representative’. (Covering clause 2 says that the ‘Queen’s’ powers extend to her heirs.) This means that the Governor-General has been given certain powers to act on behalf of the King. The role of the Governor-General is not just defined by the Constitution; it is also defined by custom and tradition.

While executive power is exercised by the Governor-General, in reality this is normally done on the advice of the Prime Minister and ministers, who have day-to-day responsibility for governing Australia. The Governor-General does not have the authority to make decisions on behalf of the government, but has a role in both the government and the Parliament.

Responsible government

The separation of powers works together with the principle of ‘responsible government’ to guide the way law is made and managed. Responsible government means that a party or coalition of parties must maintain the support of the majority of members of the House of Representatives in order to remain in government. This provides another check on the Executive, ensuring they are accountable to the Parliament and do not abuse their power.


The origins of the principle of the separation of powers can be traced back as far as ancient Greece. It was made popular by French philosopher Charles de Montesquieu in his book L'Esprit des Lois (the Spirit of the Laws) (1748). He wrote that a nation's freedom depended on the 3 powers of governance—legislative, executive and judicial—each having their own separate institution. Montesquieu’s ideas have since been widely used in the development of many democratic countries.

Separation of powers in Australia.

This diagram illustrates the principle of the separation of powers. The Parliament, Executive and Judiciary have separate powers.

Parliamentary Education Office (


This diagram illustrates the separation of powers in the Australian system of government. The Parliament (represented by an icon of Australian Parliament House) has the power to make and change law. The Executive (represented by a group of people) has the power to put law into action. The Judiciary (represented by an icon of a scale) has the power to make judgements on law. The three groups—Parliament, Executive and Judiciary—are connected.