Commonwealth of Australia v Mewett, v Rock, v Brandon

The High Court of Australia considered appeals by the Commonwealth of Australia against decisions of the Federal Court of Australia in three separate cases involving the respondents, Mewett, Rock, and Brandon. The dispute concerned the validity of certain provisions of the *Migration Act 1958* (Cth) and their application to the respondents, who were non-citizens detained under those provisions. The core of the controversy lay in whether the Commonwealth's actions in detaining the respondents constituted an unlawful exercise of executive power, particularly in light of the constitutional separation of powers.

The central legal issue before the High Court was whether the detention of non-citizens by the executive government, pursuant to powers conferred by Parliament, was constitutionally permissible. Specifically, the Court had to determine if the detention provisions of the *Migration Act* impermissibly infringed upon the judicial power of the Commonwealth, as vested in the courts by Chapter III of the Constitution. This involved an examination of the constitutional limits on the Parliament's ability to confer powers on the executive that might be seen as encroaching upon the functions traditionally exercised by the judiciary, such as the determination of guilt or innocence and the imposition of punishment.

The Court, in a joint judgment, held that the detention provisions were constitutionally valid. Brennan CJ, Toohey and McHugh JJ reasoned that the detention of non-citizens under the *Migration Act* was not an exercise of judicial power, but rather a non-punitive measure for the purpose of immigration control. They distinguished this from the exercise of judicial power, which involves the determination of rights and liabilities in accordance with law. The Court affirmed that Parliament has the power to legislate with respect to immigration, including the power to provide for the detention of non-citizens, and that such legislation does not necessarily contravene Chapter III of the Constitution, provided it does not purport to vest judicial power in the executive. The appeals were allowed, and the decisions of the Federal Court were set aside.