In Australia, public power is divided by what is known as the “separation of powers” between the three branches of government:

  • the legislature (the law-making body, called the Parliament in Australia );
  • the executive (the head of state, his or her advisors and various departments and agencies, also commonly called the government); and
  • the judiciary (the courts)

This division of power was part of the constitutional culture that Australia borrowed from the US. The drafters of the US Constitution (which was signed back in 1787) were heavily influenced by Charles-Louis de Secondat, Baron de Montesquieu, and his 1748 work, The Spirit of the Laws:

When the legislative and executive powers are united in the same person, or in the same body of magistrates, there can be no liberty; because apprehensions may arise, lest the same monarch or senate should enact tyrannical laws, to execute them in a tyrannical manner.

Again, there is no liberty, if the judiciary power be not separated from the legislative and executive. Were it joined with the legislative, the life and liberty of the subject would be exposed to arbitrary control; for the judge would be then the legislator. Were it joined to the executive power, the judge might behave with violence and oppression.”

Keeping power in check

The separation of powers is often referred to as a principle that not only divides power, but that also provides a system of “checks and balances”. These checks come in different forms. The most obvious is the judiciary’s role in ensuring the executive and the legislature comply with laws, including the Constitution.

In this way, the separation of powers is closely associated with the rule of law and the independence of the judiciary.

Indeed, although the rule of law is a largely contested concept, most definitions agree on the importance of an independent judicial branch to police the limits of the law as between the government and the people.

The separation of powers is a doctrine that is focused on the control and delimitation of public law. But it also has a positive application, in the sense that it allocates power to promote the common good – dividing power and responsibilities between institutions in ways that best suit their institutional capacities.

House of Representatives, seat of democracy, year six Canberra excursion highlight.


  • The parliament, which is the government body elected by citizens, is given responsibility for debating and passing the laws that will govern and constrain the public and the executive.
  • The executive, consisting of ministers, thousands of public servants and other public officials, is given the responsibility of applying those laws and day-to-day governing.
  • The judiciary, with guarantees of independence and obligations of impartiality, is given the role of interpreting the laws.

The powers at work

At this stage, you might be thinking that government ministers are also parliamentarians in the Australian system – and you’d be right. These two branches are not in fact separate.

Section 64 of the Australian Constitution requires that the government’s ministers be drawn from sitting members of parliament, and are “responsible” back to parliament. This creates a blurring of lines between the executive and the legislature.

However, despite this fusion between the executive and the legislature, the High Court has found that the judiciary must remain separate. This means that judicial power (that is, roughly, the power to conclusively resolve factual and legal disputes between parties) can only be exercised by courts, which is set out in Chapter III of the Constitution.

It also means that federal courts, with limited exceptions, can only exercise federal judicial power. At the State level, the High Court has said that there is no strict separation of powers, even judicial power. Nonetheless, the High Court has found that state governments are not permitted to interfere with the independence of state courts. These courts must maintain their impartiality and exercise their powers in accordance with fair judicial process.

Separation of powers

The separation of powers and the protection of human rights

These rules, derived from the separation of powers, are important safeguards of personal liberty. This is particularly the case in Australia because we don’t have a constitutional bill of rights. High Court Justice Deane has commented that the separation of powers “is the most important of the guarantees of rights and immunities, express or implied, under the Australian Constitution”.

In theory, the principles hold a large amount of promise in protecting individual rights and Australians’ right to due process of law. Indeed, the High Court has struck down laws that impose hearings where one party is absent, that impact the ability of judges to provide reasons for their decisions, or attempts by the executive to dictate judicial decisions.

However, there have also been worrying exceptions. The Court has allowed laws that permit the executive to detain individuals indefinitely without a judicial order, laws that require courts to issue preventative detention orders against individuals, laws that permit the government to rely on information that is not provided to other parties to the litigation, and laws that dictate mandatory sentences for certain offences.

This is why many people believe that the separation of judicial power is not a substitute for more comprehensive constitutional rights protections, like a bill of rights.