No common law defence to unlawful immigration detention

The High Court handed down its decision in Abdel-Hady v Commonwealth of Australia [2026] HCA 17 which clarified whether Commonwealth officers have a common law defence that would negate liability for the tort of false imprisonment for a period of immigration detention that was, in fact, unlawful.

The High Court decision in Abdel-Hady is in the wake of the orders in NZYQ from November 2023, when the High Court ruled that the government cannot keep a person in immigration detention indefinitely when there is no realistic prospect of removing them from Australia in the near future. That changed the law established by the earlier 2004 High Court decision in Al-Kateb's case, which authorised the Commonwealth to detain unlawful non-citizens indefinitely, even if they could not be deported anywhere and had no realistic prospect of removal in the foreseeable future.

The plaintiff, Abdel-Hady first arrived in Australia in 1997 and held various visas until 31 March 2017, when his then-current visa was cancelled under the Migration Act. He was located and detained on 22 August 2017 under s 189(1). He suffers from thrombophilia—an extreme tendency to form blood clots. The Commonwealth accepted having regard to medical assessments that from 28 July 2022 Abdel-Hady was medically unfit to travel by any commercial aeroplane. On that accepted medical position, there was no real prospect of his removal from Australia becoming practicable in the reasonably foreseeable future.

However, Abdel-Hady remained in detention until 13 February 2024, when he was release subsequent to the High Court's decision in NZYQ from 8 November 2023. Upon his release Abdel-Hady commenced proceedings in the High Court’s original jurisdiction seeking damages for false imprisonment for the period of detention that was not authorised.

The Commonwealth admitted that detention of Abdel-Hady was unlawful and the Commonwealth was vicariously liable for the tort of false imprisonment, but for the period from 28 July 2022, the date on which it became evident there was no real prospect of removal becoming practicable in the reasonably foreseeable future, to 8 November 2023, the making of orders in NZYQ.

The Commonwealth 's defence in Abdel-Hady case was based on the following points:

(1) the detaining officer acted in the purported performance of a statutory duty to detain under ss 189(1) and 196(1) of the Migration Act;

2) the detaining officer so acted in conformity with the law as declared in a prior decision of the High Court, being Al-Kateb; and

(3) the detaining officer was under an independent legal duty to obey the law as declared by the High Court.

The High Court in Abdel-Hady's case refused to recognise the proposed Commonwealth's defence.

In practical terms, where detention is not authorised by law the detaining officer is liable for false imprisonment, and the Commonwealth may be vicariously liable.

What does this mean in practice?

In practical terms, where detention is not authorised by law the detaining officer is liable for false imprisonment, and the Commonwealth may be vicariously liable.

First, it reinforces that false imprisonment is a strict tort. Liability turns on whether detention was authorised by law. If the legal authority is absent, the detention is unlawful, even if the officer acted in good faith or in accordance with what was previously understood to be the law.

Second, it confirms that the constitutional consequences of NZYQ are not confined to prospective release decisions. They also have downstream implications for civil liability and damages claims for periods of detention that were not authorised.

Third, it signals that courts will be cautious about recognising new common law defences that would dilute established protections against unlawful detention.

For people affected by prolonged immigration detention, the decision is another reminder that the legality of detention can change when constitutional assumptions are revisited, and that remedies may include damages where detention is shown to have been unlawful.

If you or a family member has been held in immigration detention and there are questions about whether removal was realistically practicable within a reasonably foreseeable timeframe, it may be worth obtaining advice about the lawfulness of detention and potential remedies.

This post is general information only and not legal advice.