NZYQ v Minister for Immigration

NZYQ v Minister for Immigration is a 2023 decision of the High Court of Australia. It is a landmark case in Australian constitutional law, concerning the separation of powers under the Australian Constitution. It was the first judgment of the Gageler court.

The decision is notable for having overturned Al-Kateb v Godwin, in which the Gleeson court held the Migration Act could be applied to authorise the indefinite detention of stateless persons.

The court ruled that when properly interpreted, the Migration Act was beyond the legislative power of the Commonwealth insofar as it applied to the plaintiff. This was because under Australia's constitutional system, penal or punitive detention may only occur where criminal guilt is being punished by the judiciary. The plaintiff's detention was presumed to be punitive, and the Commonwealth failed to argue that there was an alternative, non-punitive reason for his detention.

The Commonwealth attempted to argue that the plaintiff's detention was for purpose of his eventual deportation, a non-punitive purpose. However, because there was no real prospect of the plaintiff being removed from Australia in the reasonably foreseeable future, the court did not recognise this as an alternative, valid purpose justifying his detention.

The sections of the Migration Act, whilst invalid insofar as they applied to the plaintiff, remained valid when applied to authorise detention in other circumstances where justified by a non-punitive purpose. Judges explicitly noted post sentence detention is a justified purpose when it is for public protection under federal terrorist legislation or other state legislation.