Page:NZYQ v Minister for Immigration, Citizenship and Multicultural Affairs.pdf/22

Gageler CJ Gordon J Edelman J Steward J Gleeson J Jagot J Beech-Jones J

purpose. In other words, detention is penal or punitive unless justified as otherwise.

The purpose of the law in this context, as elsewhere in constitutional discourse, must be identified at an appropriate level of generality. So identified at the appropriate level of generality, the purpose is that which the law is designed to achieve in fact. For an identified legislative objective to amount to a legitimate and non-punitive purpose, the legislative objective must be capable of being achieved in fact. The purpose must also be both legitimate and non-punitive. "Legitimate" refers to the need for the purpose said to justify detention to be compatible with the constitutionally prescribed system of government. Consistently with the principle in Lim, the legitimate purposes of detention – those purposes which are capable of displacing the default characterisation of detention as punitive – must be regarded as exceptional.

Consistency with the Lim principle accordingly entails that "a Commonwealth statute which authorises executive detention must limit the duration of that detention to what is reasonably capable of being seen to be necessary to effectuate an identified statutory purpose which is reasonably capable of being achieved".