NZYQ v Minister for Immigration, Citizenship and Multicultural Affairs

Administrative detention of an unlawful non-citizen under the Migration Act is constitutionally valid only while removal remains practicable; once there is no real prospect of removal becoming practicable in the reasonably foreseeable future, continued detention is punitive and contravenes Chapter III of the Constitution, so the detainee must be released (unanimously overruling Al-Kateb v Godwin).