The aliens power, reasonable suspicion and (un)lawful detention

Jordan Smith

The High Court was required to consider whether, in light of its earlier decision in Love v The Commonwealth; Thoms v The Commonwealth (2020) 270 CLR 152 (Love), the detention of Mr Thoms – a ‘non-citizen non-alien’ – between 28 September 2018 and 11 February 2020 had been unlawful.

The High Court held that the aliens power under s 51(xix) of the Constitution supports detention of a non-alien under s 189(1) of the Migration Act 1958 (Cth) if the relevant migration officer reasonably suspects that the non-alien is an unlawful non-citizen at the time of their decision.


On 28 September 2018, Mr Thoms was detained under s 189(1) on the basis that he was neither an Australian citizen nor held a valid Australian visa.

In November and December 2018, a departmental officer was made aware of Mr Thoms’ Aboriginal descent, his identification as an Aboriginal Australian and his High Court challenge to the Commonwealth’s authority to detain him due to his Aboriginality.

On 11 February 2020 in Love, the High Court by majority found that Mr Thoms was not within the reach of the aliens power conferred by s 51(xix), by reason of his satisfying the tripartite test in Mabo v Queensland [No 2] (1992) 175 CLR 1.

Later on 11 February 2020, a departmental officer arranged for Mr Thoms’ immediate release from detention. At all preceding times, all relevant departmental officers had maintained a suspicion that Mr Thoms was an unlawful non-citizen.


The court unanimously (Kiefel CJ, Keane and Gleeson JJ at [21], Gageler J at [45], Gordon and Edelman JJ at [51] and Steward J at [87]) held that Mr Thoms’ application was disposed of by the court’s decision in Ruddock v Taylor (2005) 222 CLR 612 (Ruddock). Mr Thoms had not applied to reopen Ruddock.

Both the plurality of Kiefel CJ, Keane and Gleeson JJ (Steward J generally agreeing), as well as a minority of Gordon and Edelman JJ, nevertheless proceeded to consider whether s 189(1) was supported by s 51(xix).

The plurality and minority each held (at [38], [69]) that, in its application to Mr Thoms, s 189(1) is constitutional as having a ‘sufficient connection’ to aliens, even though Mr Thoms himself is not an alien. They diverged, however, as to the extent of the constitutionality of s 189(1) in its application to other non-aliens.

Ruddock not distinguishable

In Ruddock, a British subject detained under s 189(1) brought an action for false imprisonment following the High Court’s quashing of the minister’s decision to cancel his visa under s 501 of the Act. The majority held (at [27], [40]) that s 189(1) was not confined to situations where a person was in fact an unlawful non-citizen, but applied when an officer had a reasonable suspicion of that classification at the time of the decision. Mr Thoms argued that the constitutional validity of s 189(1) was not decided in Ruddock. The court unanimously rejected that argument. Both the plurality (at [35]) and minority (at [85]) held that when the majority in Ruddock referred to whether s 189(1) validly applied to authorise Mr Taylor’s detention, they meant constitutionally.

Constitutionality of s 189(1)

Both the plurality and minority characterised s 189(1) as capable of applying both to aliens and non-aliens (at [25], [57]). The question for decision was whether, in its application to non-aliens such as Mr Thoms, s 189(1) was supported by s 51(xix) as a law incidental or ancillary to the subject matter of aliens. That turns on whether there is a ‘sufficient connection’ between the law and the subject matter of aliens: namely, whether the connection is more than ‘insubstantial, tenuous or distant’: Melbourne Corporation v The Commonwealth (1947) 74 CLR 31 at 79 per Dixon J.

The plurality (at [38]) and Steward J (at [87]) held that the metric of ‘reasonable suspicion’, in the sense of objectively reasonable grounds (at [31]), that a person is an alien without a valid visa is itself enough to provide a sufficient connection between s 189(1) and s 51(xix). Separately, the plurality held (at [39]) that the purpose of s 189(1), being to separate such a reasonably suspected person from the community until their immigration status is determined, was itself appropriate to provide the necessary connection.

The minority (at [61]), and Steward J (at [87]) rejected the plurality’s statement (at [23], citing Chetcuti v The Commonwealth (2021) 95 ALJR 704 at 710) that the term ‘non-citizen’, as used in the Act, is to be read as synonymous with the constitutional term ‘alien’.

The minority further held (at [75], [77]) that there is a limit on s 189(1) beyond reasonable suspicion. Namely, s 189(1) should be read down or severed so it only applies to the extent that no objective facts or law exist which would indicate to the mind of a reasonable officer that the person to be detained is within the ‘Pochi limit’, being the category of persons who could not possibly answer the description of ‘aliens’ in the ordinary understanding of the word: Pochi v Macphee (1982) 151 CLR 101 at 109.

Both the plurality and the minority held that, so far as concerned Mr Thoms’ detention, s 189(1) was constitutional. The information before the relevant migration officers at the time of their decisions was sufficient to create an objectively reasonable suspicion (plurality, [44]), or constituted such objective facts and law (minority, [83]) that Mr Thoms was an unlawful non-citizen. The officer who was informed of Mr Thoms’ Aboriginality did not know and could not reasonably have known that the High Court would make the decision it did in Love ([44]). BN

Jordan Smith

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