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In Plaintiff M96A/2016 v Commonwealth, the High Court unanimously held that a mother and daughter, who were transferred from detention in Nauru to Australia to obtain medical treatment, were validly held in immigration detention during their treatment. The case is the most recent piece in the evolving jurisprudential puzzle on the constitutional limits of mandatory immigration detention in Australia. This post traces the history of this jurisprudence, and considers the contribution that Plaintiff M96A makes.

Mandatory immigration detention and its contested constitutional limits

In 1992, the Keating government first introduced a legislative scheme for the mandatory detention of non-citizens who arrive in Australia by boat, seeking asylum. The scheme, which was originally intended to be an ‘interim measure’, was promptly challenged in the High Court on the grounds that it constituted an executive usurpation of power reserved for the courts by Chapter III of the Australian Constitution. In the landmark case of Chu Kheng Lim v Minister for Immigration, Local Government and Ethnic Affairs, the High Court upheld the mandatory detention scheme. However, in doing so, a majority of the Court signalled clearly that executive detention would only be constitutionally permissible where the detention was both directed towards a limited range of permissible purposes, and ‘reasonably capable of being seen as necessary’ to achieve one of these purposes. In the case of unlawful non-citizens, the joint judgment of Brennan, Deane and Dawson JJ (with whom Mason CJ agreed) held that laws for their detention will be valid if:

…the detention which they require and authorize is limited to what is reasonably capable of being seen as necessary for the purposes of deportation or necessary to enable an application for an entry permit to be made and considered.

The majority’s finding that the mandatory detention scheme in question was ‘reasonably capable of being seen as necessary’ for these purposes was reached via a fine-grained analysis of its features, which included a cap on the number of days that a person could spend in detention, and a provision enabling detainees to request removal from Australia.

2017 marks the 25th birthday of both mandatory detention and the Chu Kheng Lim principle. The policy and the principle have shared a dynamic adolescence, characterised by increasingly complex and creative legislative schemes, periodically tested before a High Court that has at times divided deeply over the scope of the Court’s constitutional role as a supervisor of executive detention.

It is well-established that there is an outer constitutional limit to the executive’s power to detain non-citizens. However, where this boundary lies has still not been precisely defined. There have also been periods of uncertainty about the precedential value of the Chu Kheng Lim principle. While the principle has remained ‘good law’ since it was handed down, for many years it sat uncomfortably alongside subsequent cases. Chief amongst these is the 2004 case of Al-Kateb v Godwin, in which a majority of the High Court found that executive detention of an alien expressed in the Migration Act to be for the purpose of removal would pass constitutional muster, even where there was no reasonable prospect of removal in the foreseeable future. Al-Kateb thus held that indefinite executive detention of an alien in Australia is constitutionally valid, and in doing so cast significant doubt over the ‘reasonably capable of being seen as necessary’ aspect of the Lim principle. This approach was mirrored by a majority of the court in Minister for Immigration and Multicultural and Indigenous Affairs v Al-Khafaji and Re Woolley, both of which were also handed down in 2004.

More recent cases have raised questions about the precedential value of Al-Kateb, while reaffirming the Lim principle. In Plaintiff M47/2012 v Director-General of Security and Plaintiff M76/2013 v Minister for Immigration, Multicultural Affairs and Citizenship, the authority of Al-Kateb was directly challenged. In both cases, the Court found it unnecessary to decide this question, however it received attention from some judges. In M47, Gummow and Bell JJ found that Al-Kateb should be regarded as wrongly decided, while Heydon J found that it should be upheld. In M76 Hayne, Kiefel and Keane JJ all affirmed the decision in Al-Kateb. However, Hayne J also noted that there are constitutional limits to the executive’s detention powers. Specifically, his Honour said that the lawful boundaries of detention, with respect to both its purpose and its duration, must be fixed at the outset of detention by identifiable criteria.

In Plaintiff S4/2014 v Minister for Immigration and Border Protection no constitutional questions were raised by the parties. Despite this, in a unanimous judgment, the Court affirmed the constitutional findings in Lim. It then endeavoured to reconcile the Lim principle with Hayne J’s comments in M76, notably without reference to Al-Kateb.

The Plaintiff S4 Court stated that the detention of non-citizens in Australia would only be valid if it was for one of three purposes:

  • removal from Australia;
  • receiving, investigating and determining an application for a visa to enter and remain in Australia; or
  • determining whether to permit a valid application for a visa.

The Court went on to say that the purpose of detention ‘must be pursued and carried into effect as soon as reasonably practicable’, and that, to enable the courts to determine and enforce the lawfulness of detention, the duration of detention ‘must be capable of being determined at any time and from time to time.’

Plaintiff S4 was taken as a signal of a potential shift in the High Court’s approach to this area. The decision was said to cast doubt upon both the majority decision in Al-Kateb as well as the constitutionality of prolonged mandatory immigration detention where removal or processing are not being pursued actively or expediently.

Plaintiff M96A: The latest piece in the puzzle

Plaintiff M96A is the most recent High Court case to test the constitutional boundaries of Australia’s immigration detention regime. The plaintiffs, a mother and daughter originally from Iran, arrived in Australia by boat in 2013. They qualified as ‘unauthorised maritime arrivals’ under s 5AA of the Migration Act (‘the Act’), and were detained initially at Christmas Island. Subsequently, they were taken to Nauru under s 198AD, and were held in detention there.

In November 2014, the plaintiffs were brought to Australia from Nauru, for the purpose of receiving medical treatment. While undergoing treatment, they were placed in detention, first at Darwin and then at the Melbourne Immigration Transit Accommodation. They challenged this detention in the High Court.

The statutory scheme

Because they had been transferred to Nauru – a regional processing country – the plaintiffs qualified as ‘transitory persons’ under s 5(1) of the Act. Their later transfer to Australia was authorised by s 198B, which authorises the executive to bring ‘transitory persons’ to Australia for a ‘temporary purpose’. In the plaintiffs’ case, this temporary purpose was to receive medical treatment.

Notably, the plaintiffs did not seek to challenge either their removal to or detention in Nauru, or their transfer to Australia. Their only challenge was to their detention while receiving medical treatment in Australia, which they argued was unconstitutional.

This detention was governed by ss 189(1) and 196(1), which provide for the detention of ‘unlawful non-citizens’ within Australia. The plaintiffs were ‘unlawful non-citizens’ because they did not have valid visas authorising their presence in Australia. Section 189(1) requires executive officers to detain unlawful non-citizens. Section 196(1) provides that an unlawful non-citizen detained under s 189 must be kept in immigration detention until he or she is either removed from detention, taken to a regional processing country, deported or granted a visa.

For transitory persons like the plaintiffs, detention typically ends with removal from Australia. This is because s 46B precludes transitory persons from making valid visa applications without written ministerial consent. The plaintiffs had not been granted consent to apply for a visa.

There are two main ways in which a transitory person detained under s 189 can be removed from Australia:

  • Where the person no longer needs to be in Australia for the temporary purpose for which they were brought into the country, S198AD requires an officer to take them to a regional processing country as soon as reasonably practicable. Importantly, this duty arises whether or not the temporary purpose has been achieved.
  • In circumstances where s198AD does not apply, s 198(1) requires an officer to remove a transitory person, as soon as reasonably practicable, if they request removal in writing. This procedure would, for instance, apply if the transitory person does have an ongoing need to be in Australia for the temporary purpose, but nonetheless requests removal.

The issues

The Court examined the constitutional validity of the statutory scheme for the detention of transitory persons, under which the plaintiffs were detained. It looked at two relevant questions, which drew on the approach taken in Chu Kheng Lim and Plaintiff S4:

  1. Whether the detention was for a constitutionally permissible purpose, and
  2. Whether the duration of the detention was sufficiently capable of being determined by a court.

All members of the Court answered both of these questions affirmatively, and found that the plaintiffs’ detention was constitutionally valid. There were two judgments: a joint judgment by Kiefel CJ and Bell, Keane, Nettle, Gordon and Edelman JJ (‘the plurality’), and a separate judgment by Gageler J, who agreed with the plurality’s findings, and made some additional comments in obiter regarding jurisdictional facts.

The purpose of detention

The plaintiffs and the defendants divided over two questions:

  • How the purpose of the detention of transitory persons should be characterised, and
  • The constitutionally permissible purposes for executive detention of a non-citizen.

The plaintiffs argued that the purpose of the detention of transitory persons was identical to the temporary purpose for which they were brought to Australia. In their case, this was the purpose of receiving medical treatment. They further argued that detention for a ‘temporary purpose’, such as medical treatment, was not constitutionally permissible, as it did not fall within any of the three valid purposes identified in Plaintiff S4: removal from Australia, processing of a visa application and determining whether to permit a visa application to be made.

The Commonwealth, by contrast, submitted that the permissible purposes identified in Plaintiff S4 were not exhaustive. It also argued that the purpose of detaining transitory persons such as the plaintiffs was not the temporary purpose for which they were brought to Australia. Rather, the purpose of their detention was to segregate them from the Australian community (which they had no right to enter without a visa) while the temporary purpose was being pursued, and to ensure that they would be available for removal once they no longer needed to be in Australia.

The Court agreed with the Commonwealth’s characterisation of the purposes underpinning the detention. The plurality noted that there were two factors that highlight why the temporary purpose for which a transitory person was brought to Australia was not the same as the purpose of their detention.

First, detention does not need to aid the fulfilment of the temporary purpose. Indeed, the plurality noted that for transitory persons like the plaintiffs, who were brought to Australia for the purpose of receiving medical treatment, detention could well be antithetical to achieving the temporary purpose.

Secondly, the length of detention does not depend upon the temporary purpose being fulfilled. A transitory person can, for instance, ask to be removed from Australia before the temporary purpose is fulfilled, and an obligation to remove them as soon as reasonably practicable will arise under s 198(1).

Notably, the plurality found that the purposes underpinning the detention of transitory persons are the same purposes that apply to ‘all other instances involving unlawful non- citizens under s 189’. Where an unlawful non-citizen is precluded from applying for a visa, their detention is for the purpose of removal. This was the position that the plaintiffs, and most other transitory persons, found themselves in.

In this way, the Court reasoned that the detention of transitory persons in Australia was for the purpose of removal from Australia – one of the three constitutionally permissible purposes recognised in Plaintiff S4. In light of this, the plurality expressly declined to decide whether those three purposes are the only purposes that can underpin the executive detention of non-citizens. This question awaits a later case.

The duration of detention

The plaintiffs’ second argument was that detention of transitory persons by the executive infringed the constitutional separation of judicial power. This was said to be the case because the period that a transitory person would remain in detention could not be objectively determined. The plaintiffs relied on the Court’s statement in Plaintiff S4 that ‘[t]he duration of any form of detention, and thus its lawfulness, must be capable of being determined at any time and from time to time’.

The plurality affirmed this statement from Plaintiff S4, but found that the plaintiffs had misunderstood it. Their Honours held that what is required is the existence of ‘objectively determinable criteria for detention’. In other words:

Parliament cannot avoid judicial scrutiny of the legality of detention by criteria which are too vague to be capable of objective determination. This would include an attempt to make the length of detention at any time dependent upon the unconstrained and unascertainable opinion of the Executive.

All seven judges found that the scheme for the detention of transitory persons specified preconditions that had the unequivocal effect of ending detention. The plurality noted:

One precondition is that detention will come to an end under s 198(1) as soon as reasonably practicable after the transitory person asks the Minister, in writing, to be removed from Australia. Another precondition is that the person no longer needs to be in Australia for the temporary purpose.

The Court found that these preconditions make the duration of detention objectively determinable, even if the precise length of a transitory person’s detention cannot be judged at the outset. Citing Al-Kateb as authority, the plurality noted:

The detention does not become an exercise of judicial power merely because the precondition, and hence the period of detention, is determined by matters beyond the control of the Executive. This will frequently be the case where, for instance, questions arise as to whether it is reasonably practicable to remove a person from Australia.

For these reasons, the Court held that the executive detention of transitory persons was constitutionally valid.  

Jurisdictional facts

There was some discussion in the hearing over how the question of whether a transitory person has an ongoing need to be in Australia for a ‘temporary purpose’ should be determined. The Commonwealth submitted that this was a matter for an executive officer to determine, while the plaintiffs argued it was a jurisdictional fact, to be objectively determined by a court.

How this question is answered potentially impacts upon the point at which a duty to remove a transitory person from detention arises. However, it was not necessary to determine the point to decide the plaintiffs’ case, as all parties agreed that both plaintiffs had a continuing need to be in Australia to receive medical treatment.

For this reason, the plurality did not rule on this point; however Gageler J did. His Honour held that, as a matter of statutory construction, the question of whether a transitory person needs to be in Australia for a temporary purpose is one that, in the event of a dispute, must be objectively assessed by the courts. His Honour noted that there are established drafting techniques that are used when Parliament intends for a particular power or duty to be activated when the person exercising it holds a particular state of mind. These techniques are used throughout the Act. They are not, however, used in the provisions that regulate the removal of transitory persons. On the contrary, Gageler J said that these provisions ‘[cast] the precondition to the performance of the duty to remove in manifestly objective terms’.

Where to from here?

In 2014, when the High Court handed down its unanimous judgment in Plaintiff S4, it was met with anticipation. The Court’s resuscitation of Chu Kheng Lim, silence on Al-Kateb and unified articulation of tools with which to measure the constitutional limits of immigration detention were regarded by commentators as potential harbingers of a groundbreaking shift in the High Court’s approach to assessing the constitutionality of mandatory detention schemes. Arguably, these signals were made all the more compelling by the fact that they were nested in obiter dicta, in a case in which no constitutional issue was raised by the parties.

Three years on, the winds of change seem a little weaker. In Plaintiff M96A, the Court affirmed the Lim principle and applied the approach set out in Plaintiff S4, but stopped short of conclusively endorsing the idea that there are only three permissible purposes for Commonwealth executive detention.

Plaintiff M96A also hints subtly at an attempt to reconcile the idea, strongly signalled in Plaintiff S4, that there are definitive constitutional limits on executive powers to detain non-citizens, with the fractured jurisprudence in this area to date. This is reflected in the Court’s finding that constitutional limits on the duration of detention merely require that the period of detention is defined by reference to objective criteria, rather than that the length of detention be objectively determinable. That immigration detention need not be of short or predictable duration to be constitutionally valid is underlined by the plurality’s citation of Al-Kateb when commenting that detention for the purpose of removal will not impinge on judicial power merely because removal is preconditioned on matters beyond executive control. 

This approach seems to place a heavier emphasis on formic limits to executive immigration detention than on practical limits to the duration of detention in any given case. This is arguably a shift away from the approach adopted in Chu Kheng Lim, where the majority attached significant weight to the presence of a maximum time limit on the length of any person’s detention.

The decision in Plaintiff M96A suggests that further challenges on Lim grounds may be most promising where the duration of a non-citizen’s detention is controlled by broad executive discretion, or where removal or visa processing is not being actively pursued by the executive. With respect to transitory persons brought to Australia for a temporary purpose and held in detention, it may be that there is scope for further litigation where the facts differ materially from those in Plaintiff M96A. Examples may include where a plaintiff wishes to challenge an executive decision to bring them to Australia for a temporary purpose, or where there is a live question over whether a transitory person still needs to be in Australia for the ‘temporary purpose’ that brought them to the country.

First published in AusPubLaw.

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