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An officer of the Commonwealth detained a non-citizen based on the High Court’s declaration of the law as it stood at the time. However, the High Court subsequently declared the law in a different way, rendering that detention unlawful. The officer’s reliance on the former declaration was no defence to the tort of false imprisonment, writes Sergio Zanotti Stagliorio.
In Abdel-Hady v Commonwealth of Australia [2026] HCA 17, the High Court of Australia ruled that, if an officer detained an unlawful non-citizen “in the purported performance of a statutory duty to detain in conformity with the law as declared in a prior decision of this court which has been held in a subsequent decision of this court to have been erroneous”, that prior decision is not a defence to liability for the tort of false imprisonment.
Previous High Court authority
In Al-Kateb v Godwin [2004] HCA 37, the High Court had ruled that detention under ss 189 and 196 of the Migration Act 1958 (Cth) of an “unlawful non-citizen” (defined under ss 13-14 of the act as a non-citizen in Australia who does not hold a visa that is in effect) was non-punitive and therefore did not contravene Ch III of the Constitution (separation of judicial power), with the result that ss 189 and 196 effectively authorised indefinite detention, meaning detention until the person in question could be removed under s 198.
Departure from Al-Kateb
Al-Kateb was seen as the law from 2004 until it was overruled by the High Court in 2023 in NZYQ v Minister for Immigration, Citizenship and Multicultural Affairs [2023] HCA 37.
In NZYQ, the High Court ruled that detention under ss 189 and 196 becomes unlawful from the moment when there is no real prospect of the removal of the person in question from Australia becoming practicable in the reasonably foreseeable future. In other words, from that moment onwards, detention would ordinarily amount to the tort of false imprisonment, meaning that damages might be claimed.
Abdel-Hady
In Abdel-Hady, the plaintiff (Safwat Abdel-Hady) was an unlawful non-citizen. An officer of the Commonwealth detained him under s 189, based on the law as understood at the time, namely Al-Kateb. However, after he was taken into immigration detention under s 189, and while he was kept in detention under s 196, the High Court handed down its judgment in NZYQ.
In Abdel-Hady, the High Court ruled that ss 189 and 196, as purportedly applied to persons for whom there is no real prospect of removal from Australia becoming practicable in the reasonably foreseeable future, contravened Ch III of the Constitution and were therefore invalid ab initio. In other words, that those provisions were understood for a period (from 2004 to 2023) as applying to those persons does not mean they did. That is to say that what the High Court declared to be the law in NZYQ operated with retrospective effect, meaning that it has always been the law, even though only recently declared to be the case.
In short, even though the officer who removed Mr Abdel-Hady understandably held him in immigration detention based on what the law was understood to be at the time, it nevertheless amounted to unlawful detention, as NZYQ subsequently ruled that the detention in circumstances such as his was not authorised by ss 189 or 196.
In those circumstances, such unlawful detention would normally constitute the tort of false imprisonment, meaning that damages could be claimed.
The question stated for the opinion of the High Court was as follows: “Do the Commonwealth and its officers have a defence to liability for the tort of false imprisonment with respect to the immigration detention of the plaintiff in the period between 28 July 2022 and 8 November 2023?”
In other words, the question was: if an officer detained an unlawful non-citizen “in the purported performance of a statutory duty to detain in conformity with the law as declared in a prior decision of this court which has been held in a subsequent decision of this court to have been erroneous”, is that prior decision a defence to liability for the tort of false imprisonment?
The High Court answered that question in the negative.
Chief Justice Gageler and Gleeson and Beech-Jones JJ held as follows at [7]:
No such common law defence should be recognised. No development of the common law can be inconsistent with constitutional principle. Far from protecting the judicial declaration of the law and enhancing the responsibility of the executive branch of government to ascertain the law that limits its own power and to comply with that law, as the Commonwealth argues, recognition of the propounded common law defence would subvert the accepted foundational constitutional principles of judicial authority and executive responsibility. It would transform the responsibility of an officer of the executive government of the Commonwealth to ascertain and comply with the law that limits the power of the officer into a common law immunity from a common law consequence of action which has subsequently been judicially determined to have transgressed such a legal limit and therefore to have exceeded that power.
Justices Gordon, Edelman, Steward, and Jagot held to the same effect in separate judgments.
Conclusion
Even though the officer in this case understandably applied the law as declared at the time by a court; if that court then makes a different declaration, it is the latter declaration that applies, and applies with retrospective effect, meaning that reliance on the law as previously declared is no defence to the tort of false imprisonment.
As much as that puts officers in the invidious position of taking action that may be subsequently declared to be unlawful, such invidiousness is not a deference to the tort.
Sergio Zanotti Stagliorio is a barrister and lecturer.
