Garlett v Western Australia [2022] HCA 30 | Case summary

Garlett v Western Australia [2022] HCA 30 | Case summary | Zoe

KIEFEL CJ, KEANE AND STEWARD JJ. On 19 November 2017, the appellant ("Mr Garlett"), in company with others, entered a dwelling without consent and, with threats of violence, stole a pendant necklace and $20 in cash. He pretended to be armed with a handgun. He was arrested the following day and remanded in custody. He was charged with, and pleaded guilty to, the offences of robbery and assault with intent to rob, contrary to ss 392 and 393, respectively, of the Criminal Code (WA)[1] ("the November 2017 offending").
For the November 2017 offending, Mr Garlett was sentenced in July 2019 to a total effective sentence of three years and six months' imprisonment, backdated to commence on 20 November 2017[2]. On 12 January 2021, he was sentenced to a further five months' imprisonment for an offence of criminal damage committed while he was in prison. Mr Garlett's release date was 19 October 2021[3].
Mr Garlett was 23 years old at the time of the November 2017 offending[4]. He has a lengthy history of offending, which includes numerous aggravated burglaries, aggravated robberies and stealing motor vehicles[5]. Generally speaking, he has a record of poor behaviour while in custody[6]. His history of offending, with his first recorded convictions in April 2007, is related to his abuse of alcohol and drugs, which was already manifest when he was 12 years old. Mr Garlett was released into the community in September 2017 from imprisonment for earlier offending, but shortly thereafter he tested positive for methylamphetamine, amphetamine and cannabis[7]. It is noteworthy that the November 2017 offending occurred only two months later. By his admission, Mr Garlett was injecting methylamphetamine daily at the time of that offending[8].
In Fardon v Attorney‑General (Qld)[9], Gleeson CJ observed that "difficult questions involving the reconciliation of rights to liberty and concerns for the protection of the community ... typically arise in the case of a small number of unfortunate individuals who suffer disorders which make them dangerous to others". The November 2017 offending, and Mr Garlett's history of offending, associated with his long‑term abuse of alcohol and drugs, particularly methylamphetamine, may be reason for a concern that he is one of these unfortunate individuals.
The High Risk Serious Offenders Act 2020 (WA) ("the HRSO Act") is addressed to that concern and to reconciling that concern with the right to liberty. The HRSO Act provides that the first respondent ("the State") may apply to the Supreme Court of Western Australia for a restriction order in relation to a "serious offender under custodial sentence who is not a serious offender under restriction"[10].
On 29 July 2021, the State applied for a restriction order in relation to Mr Garlett, on the basis of the November 2017 offending. In response to the State's application, Mr Garlett challenged the validity of the HRSO Act or parts of it. Subsequently, his challenge was confined to the validity of items 34 and 35 of Subdiv 3 of Div 1 of Sch 1 to the HRSO Act. These items specify that the offences of robbery and assault with intent to rob[11] - of which Mr Garlett was convicted - are both a "serious offence" for the purposes of the HRSO Act[12].
Initially, Mr Garlett's challenge was put on several bases[13]; but the only basis now pursued is that the HRSO Act, insofar as its provisions apply to a person who has been convicted of robbery, as referred to in item 34, is contrary to Ch III of the Constitution by reason of the principle in Kable v Director of Public Prosecutions (NSW)[14]. The decision in Kable[15] established that, by reason of the integrated system of courts postulated by the provisions of Ch III of the Constitution[16], State legislation which purports to confer upon a State Supreme Court a function which substantially impairs the institutional integrity of such a court in its role as a repository of federal jurisdiction is "repugnant to or incompatible with" that role and is, therefore, invalid[17].
For the reasons that follow, the question whether item 34 of Subdiv 3 of Div 1 of Sch 1 to the HRSO Act infringes the Kable principle should be resolved in favour of the validity of the HRSO Act. This conclusion accords with the decision of this Court in Fardon, which concerned legislation, the Dangerous Prisoners (Sexual Offenders) Act 2003 (Qld) ("the DPSO Act"), which is, as will be explained, materially indistinguishable from the HRSO Act.

A preliminary hearing of the State's application for a restriction order was held on 13 October 2021. As Mr Garlett was due to be released from custody soon thereafter, it was necessary to determine promptly whether orders should be made under s 46 of the HRSO Act. That required a decision as well on the challenge to the validity of the impugned parts of the HRSO Act[18].
The primary judge (Corboy J) concluded that the impugned parts of the HRSO Act did not confer powers on the Court that were repugnant to or incompatible with that Court's role as a repository of federal jurisdiction under Ch III of the Constitution[19]. Relevantly, his Honour declared that none of the provisions of the HRSO Act contravened Ch III of the Constitution, insofar as they apply to a serious offender under custodial sentence who has been convicted of the offence of robbery as referred to in item 34 of Subdiv 3 of Div 1 of Sch 1 to the HRSO Act.
His Honour also concluded that there were reasonable grounds for believing that the Court might, in accordance with s 7 of the HRSO Act, find that Mr Garlett was a "high risk serious offender"; and consequently held that an order should be made under s 46(2)(c) of the HRSO Act for Mr Garlett to be detained until the application was finally determined[20].
Mr Garlett appealed to the Court of Appeal of the Supreme Court of Western Australia seeking to set aside the declaration on grounds which included the Kable ground. On 21 December 2021, Gordon J ordered that that part of the cause pending in the Court of Appeal concerned with the Kable ground be removed into this Court pursuant to s 40 of the Judiciary Act 1903 (Cth).
As the primary judge noted, the legal consequences of the designation of an offence as a "serious offence" attach only by force of other relevant provisions of the HRSO Act, and so it is "not especially meaningful" to consider the validity of item 34 separately from the rest of the HRSO Act[21]. In order to appreciate the arguments agitated by Mr Garlett in this Court, it is necessary to set out the provisions of the HRSO Act at some length.

The primary judge concluded, by reference to Fardon, that the legislature had not compromised the independence or impartiality of the Court by conditioning the making of a restriction order under the HRSO Act upon the commission of a "serious offence" of the kind identified in Sch 1[41].
His Honour made three points about the operation of s 7(3). First, the matters for the Court's consideration were specified by Parliament, and were not specified "by an executive act in any relevant sense"[42]. Secondly, what is a "relevant matter" that the Court is permitted to take into account by virtue of s 7(3)(j) is determined by the objects of the HRSO Act and a consideration of its provisions as a whole[43]. And thirdly, s 7(3) emphasised the evaluative nature of the decision required by s 7(1): it does not constrain the matters which the Court may consider in making a finding under s 7(1)[44].
The primary judge held that s 48 of the HRSO Act was to be interpreted as requiring the Court to make the order that is "least invasive or destructive" of the right to liberty of the person subject to the order, while ensuring an adequate degree of protection for the community[45]. In this regard, his Honour followed the approach of Beech J in Director of Public Prosecutions (WA) v DAL [No 2][46] in determining whether a continuing detention order or supervision order should be made under s 48[47].
The primary judge held that the HRSO Act incorporated procedures that are the "hallmarks of traditional forms and procedures" of the judicial process: the onus of proof rests on the State; the "ordinary" rules of evidence apply (with one common exception relating to statements of information and belief[48]); the offender has a right to appear and adduce evidence[49]; experts must prepare an "independent report"[50]; the State is under a continuing obligation of disclosure and must serve expert reports; hearings are conducted in public; and there is a right of appeal[51]. Having regard to the circumstances, his Honour concluded that the provisions of the HRSO Act maintained the "essential character" of the Court as a court exercising State and federal judicial power: impartiality, independence, procedural fairness, and open decision‑making[52].
The primary judge also concluded that the purpose of the HRSO Act was protective, not punitive. His Honour noted that the central provisions of the HRSO Act and its objects were, in substance, protective and not punitive in character[53]. Three further features of the HRSO Act confirmed its protective character, namely the establishment of the High Risk Serious Offenders Board, the imposition of obligations on "supporting agencies" in respect of serious offenders, and the circumstance that the HRSO Act required periodic reviews and thereby did not provide for indefinite detention in any relevant sense[54].

Mr Garlett's argument was not put on the basis that the Court, in exercising the powers conferred on it by the HRSO Act, exercises federal jurisdiction. Rather, it was that its exercise of those powers is inconsistent with it being a repository of federal jurisdiction because the exercise of power pursuant to the impugned provisions is non‑judicial. The manner in which the argument is framed rightly recognises that the power to make a continuing detention order or a supervision order under the HRSO Act has been conferred by a State Parliament on a State court. Whether or not that power is judicial or non‑judicial in character is not determinative as to whether the Kable principle has been infringed. The suggestion that investing a power in a State court to order preventive detention is repugnant to its institutional integrity as a Ch III court cannot stand with this Court's decision in Fardon; and that is so whether or not that power is properly characterised as judicial power[56]. Accordingly, the Lim principle has no application to establish the invalidity of the HRSO Act. Even if the HRSO Act were a law of the Commonwealth, it would not contravene the Lim principle.
Nevertheless, Mr Garlett sought to maintain the submission that the power conferred by the HRSO Act, being non‑judicial in character, was a factor pointing to the conclusion that the impugned provisions of the HRSO Act substantially impair the institutional integrity of the Court. That argument should be rejected. Indeed, the circumstance that the power invested in the Court is recognisable as an orthodox exercise of judicial power may be seen as a positive indicator of validity.
Mr Garlett sought to sideline the authority of Fardon by noting differences between the HRSO Act and the DPSO Act. It was said that because s 48 of the HRSO Act provides that the Court must make a restriction order if satisfied of the matters in s 7, the absence of a discretion in the Court not to make the order means that the Court is required to act under dictation from the executive.
It was also argued that the HRSO Act is significantly different from the DPSO Act, which applied only to a "serious sexual offence"[57]. This submission was developed by a number of contentions advanced in various ways; but the gravamen of Mr Garlett's argument was that the offence of robbery under s 392 of the Criminal Code (WA) simply cannot be sufficiently "serious" to be a permissible basis for seeking a restriction order. It was also said on Mr Garlett's behalf that because there is no correlation in the HRSO Act between the nature of the "serious offence" which may trigger the operation of the Act, and the risk of harm against which a detention order is to protect, the HRSO Act impermissibly creates a scheme under which the Court may decide that a person, having served a term for rape, should not be released from prison because of the risk that the person might commit a robbery.
Mr Garlett's arguments may now be considered.

As is apparent from the passage cited from Blackstone, at the time that author wrote, the protective or preventive purpose of the criminal law was vindicated to the most extreme extent possible by the removal of the offender from the community either by the imposition of the death penalty or by "perpetual confinement, slavery, or exile". And in the United States, when Holmes wrote, the death penalty was routinely imposed for serious crimes. None of the means of prevention of crime mentioned by Blackstone is now available in Australia as a result of legislative intervention to mitigate the extreme harshness of the criminal law of these earlier times. But the merciful development of the criminal law has also meant that the risk to the community posed by the release of a disordered individual who has served his or her proper sentence has been revealed as an issue left unresolved by the enforcement of the criminal law.
Late in the 20th century in Australia, the cases of Veen v The Queen[64] and Veen v The Queen [No 2][65] added special poignancy to this unresolved issue. These decisions established as a principle of the criminal law in relation to sentencing that protection of the community from the dangerous propensities of an offender could not justify a sentence disproportionate to the moral culpability of the offender and the need for retribution appropriate to the seriousness of the offending. The principle stated by this Court in Veen [No 1] and Veen [No 2] imposed a limit upon the extent to which the protection of the community from a disordered individual could be taken into account in the exercise of the discretion of a sentencing judge.
In Fardon, Gleeson CJ, in discussing this Court's decisions in Veen [No 1] and Veen [No 2], noted the tension between the practical effect of each of the two decisions[66]. In Veen [No 1], this Court upheld an appeal against a sentence of life imprisonment imposed for the protection of the community upon Mr Veen, who had been charged with murder but convicted of manslaughter on the ground of diminished responsibility, the sentencing judge having taken the view that, by reason of brain damage which could cause uncontrolled aggression when affected by alcohol, Mr Veen was likely to kill or injure someone if he were released. This Court reduced Mr Veen's sentence to imprisonment for 12 years. Subsequently, Mr Veen was released from custody, and nine months later he stabbed and killed a man. For this crime, the Crown accepted a plea of manslaughter on the ground of diminished responsibility. Once again, Mr Veen was sentenced to life imprisonment, on the ground that he was a danger to society, and was likely to kill again when released. This Court upheld that sentence in Veen [No 2].
In Fardon, Gleeson CJ did not seek to reconcile the outcome in Veen [No 1] with the outcome in Veen [No 2], given that there was no apparent difference of approach in terms of principle; but his Honour observed that "[t]he facts of the case reveal a common problem with which courts and legislatures have to deal"[67]. One legislative response to that problem was the DPSO Act and its analogues, such as the HRSO Act. That response addressed the need to protect the community from disordered individuals in a way that the criminal law as expounded in Veen [No 1] and Veen [No 2] does not; and that response proceeded by way of a regime which eschewed entirely the purposes of deterrence and retribution that characterise punishment under the criminal law.
The purpose of a legislative regime, such as the DPSO Act or the HRSO Act, is discernibly distinct from the imposition of retribution or deterrence pursued by the criminal law. To the extent that detention or supervised release is part of the legislative regime, the character of the curtailment of the liberty of the individual offender under the regime can be seen to be protective rather than punitive because any curtailment of liberty must be supported by the risk evaluation contemplated by s 7 of the HRSO Act. In that evaluation, considerations of retribution and deterrence, central to sentencing by way of punishment under the common law, have no part to play. In addition, any curtailment of liberty must be no greater than is necessary adequately to protect the community from the demonstrated unacceptable risk of harm to the community[68]. Further, any curtailment of liberty is subject to regular review to ensure that the evaluation of risk and response remains current. Where detention can be justified only by that evaluation and cannot be continued beyond the currency of such an evaluation, the purpose of detention and of the regime under which it is imposed can readily be seen to be distinct from the purpose of punishment.
The HRSO Act can be seen to be protective, rather than punitive, in its purpose and effect because:

Section 48 of the HRSO Act contemplates that the Supreme Court "must" make a restriction order if it is satisfied that the offender is a "high risk serious offender". The DPSO Act preserved a discretion in the Supreme Court of Queensland as to whether to make an order where a prisoner was assessed to pose an unacceptable risk of harm to the community[93]. On Mr Garlett's behalf, emphasis was placed on this circumstance as a point of distinction between the two Acts. That submission must be rejected.
The terms of s 7(1) must be read in conjunction with s 48[94]. Section 48 authorises and requires the Court to make a restriction order only where a positive determination has been made in accordance with s 7 of the HRSO Act.
The circumstance that the Court is not invested with a residual discretion to decline to make a restriction order does not establish that it is acting upon the dictation of the executive government as to the manner of deciding the case or its outcome. While s 48(1) is couched in mandatory terms, the terms of s 48(2) and the definition of "high risk serious offender" in s 7(1) mean that the judicial evaluation upon which the Court's determination depends is essential to the making of a restriction order. The decisive nature of the Court's evaluation is distinctly inconsistent with the suggestion that it must act upon the dictation of the legislature or the executive as to whether a restriction order should be made in any particular case.
Whether or not a risk that an offender will commit a "serious offence" is "unacceptable" is a question which requires the Court's judgment as to the nature and extent of the harm said to be in prospect. Further, whether a restriction order is "necessary" to protect against that risk requires recognition of what would otherwise be the offender's entitlement to be at liberty, an entitlement not lightly to be denied. The Court must consider whether a restriction order is necessary to ensure adequate protection of the community[95]. The Court is required to perform this evaluative exercise and come to its own determination as to whether to make a restriction order; it does not automatically follow from the inclusion of an offence in Sch 1 that a restriction order must be made.
In Emmerson, French CJ, Hayne, Crennan, Kiefel, Bell and Keane JJ observed that the legislation under consideration in that case provided that the "Supreme Court [of the Northern Territory was] authorised to determine whether the statutory criteria set out [were] satisfied and, if they [were], the Court must make the declaration sought" by the executive government[96]. The legislation then "provide[d] the consequences which follow from the Supreme Court's declaration". Their Honours said[97]:

It was submitted on behalf of Mr Garlett that Fardon is authority only for the narrow proposition that legislation empowering a State court to order detention of a person serving a sentence for a "serious sexual offence", for the purpose of protecting the community and on the terms provided for in the DPSO Act, does not attract the Kable principle.
It was said that the offence of robbery under s 392 of the Criminal Code (WA) is inherently insufficiently serious to be capable of being regarded as a basis for a restriction order. Mr Garlett focussed on what was said to be the unexceptional nature of robbery as an offence to argue that the making of a restriction order, in addition to the sentence imposed on the offender for the offence of which he or she was convicted, is disproportionate to the seriousness of that offence for which proper punishment has already been imposed. These contentions cannot be accepted.
First, Mr Garlett's argument fails to appreciate that the imposition of a restriction order is not by way of further punishment for the "serious offence" of which the offender has been convicted, but a precaution that has been judicially assessed as necessary for the purpose of protecting the community. A restriction order does not contravene the principle of "double jeopardy"[98], in the sense that it punishes the offender twice, for the offence that engages the application of the HRSO Act. The protective purpose of the HRSO Act is not undermined by a lack of correlation between the past offence, which conditions the operation of the legislation, and the harm to the community from the commission of any "serious offence" in the future.
Secondly, Mr Garlett's argument confuses orthodox notions of proportionality in sentencing with the radically different notion of a judicial usurpation of the responsibility of the legislature to determine the degree of culpability appropriate to various categories of misconduct. The determination of the relative seriousness of criminal offences, reflected in the maximum sentences for those offences, is a matter for the legislature.
The inclusion of an offence, such as robbery, in Sch 1 to the HRSO Act reflects a legislative judgment as to the kinds of offences which may be such as to cause harm of a kind from which the community needs protection different from that provided by the criminal law. It is not inimical to the institutional integrity of the Court to act upon a legislative judgment that robbery should be included in the serious offences listed in Sch 1. That is especially so where an element of the offence is violence to person or property, or the threat of such violence. It is to be borne in mind that the maximum penalty for a contravention of s 392 of the Criminal Code (WA) ranges between imprisonment for 14 years, 20 years and life, depending upon the circumstances of the contravention.
It is also to be noted that the sexual offences in respect of which the operation of the DPSO Act depended covered a range of seriousness, with some offences attracting higher penalties than others, but with any one offence being sufficient to engage the application of the regime. In Benbrika, Edelman J noted that this Court in Fardon respected the judgment of the legislature that all the offences on this spectrum "could potentially involve harm to the community sufficient to permit consideration of a continuing detention order"[99].
As his Honour also noted, "'conduct is regarded as criminal for the very reason that its commission harms society, or some part of it', and it is rarely the role of a court to second‑guess Parliament's decision about the seriousness of the harm that various crimes will have to the community"[100]. Similarly, in Vella, the range of offending on which the power of the Supreme Court and the District Court of New South Wales was conditioned was acknowledged to be "very wide"[101].
In Magaming v The Queen[102], it was said:

Whatever may be said in the abstract of the relative seriousness of an offence designated as a "serious offence" for the purposes of the HRSO Act, it is always for the Court to determine whether there is an "unacceptable risk" that the offender will commit such an offence, having regard to the evidence as to the nature of the offending and the circumstances of the offender. Importantly, the evaluative exercise contemplated by s 7 of the HRSO Act is not an exercise involving the notional ordering in the abstract of the relative culpability of categories of offences. Rather, s 7 contemplates a practical evaluation concerned with the circumstances of the particular offending and the particular offender. While the requirement of an evaluation under s 7 depends upon the offender having been convicted of a "serious offence", ss 7 and 48 do not envisage the possibility that a restriction order might be made to prevent the commission of a serious offence, whether of the same kind or of another kind, unless the risk of further offending involves a real threat of harm to the community[103].
In the case of Mr Garlett, that practical evaluation could be expected to involve consideration of the November 2017 offending, and the relationship between his history of offending and his long‑term abuse of methylamphetamine. The Court would be required to consider the implications of these circumstances in relation to the likelihood that he would reoffend, and the nature of that offending, if he were to be released into the community with or without supervision. A restriction order will only be made consequent upon an assessment of all the circumstances of the "serious offence" and the offender. There can be no doubt that a judge tasked with the determination of the State's application for a restriction order against Mr Garlett would make a restriction order of either kind only after anxious consideration of Mr Garlett's prospects of freeing himself from the grip of methylamphetamine and the extent to which those prospects bear upon the likelihood that the community will continue to be exposed to robberies and like crimes involving, for example, the horrors of home invasions[104]. As Derrick J said in Western Australia v Patrick [No 5][105]:

Mr Derek Ryan is currently subject to a supervision order under the HRSO Act. Like Mr Garlett, he was convicted of the "serious offence" of robbery. Mr Ryan was granted leave to provide written submissions on the basis that he sought to make submissions "which the Court should have to assist it to reach a correct determination"[114], and which had not then been presented.
The thrust of Mr Ryan's submissions in this regard was that the HRSO Act enlists the Court to give effect to legislative policy[115].
Challenges to State legislation have succeeded in this Court in International Finance Trust Co Ltd v New South Wales Crime Commission[116], South Australia v Totani[117] and Wainohu v New South Wales[118]. None of these cases was concerned with a preventive detention regime. The legislation challenged in the first of these cases provided for asset‑freezing orders[119]. Totani and Wainohu were concerned with control orders[120]. In each of these two cases, the flaw in the legislation lay in the co‑opting of the courts by the executive to implement decisions of the executive.
Mr Ryan relied particularly upon this Court's decision in Totani. The Magistrates Court of South Australia was required to make a control order on an application by the Commissioner of Police against a defendant if the defendant was a member of a "declared organisation" without any need to determine, by ordinary judicial processes, whether the defendant was actually engaged in serious criminal activity, a "declared organisation" being an organisation declared to be such by another member of the executive government[121]. This was a clear case of enlistment of the Court to give effect to the decision of the executive government in relation to particular individuals.
Under the HRSO Act, as with the DPSO Act, there is no enlistment of the Court to implement the decisions of the executive government. As has been explained, under the HRSO Act, the Court, in making a restriction order, is required to make a substantial evaluative judgment in order to make that determination. In addition, the Court is obliged to proceed to make that determination by reference to the processes characteristic of the exercise of judicial power. And the Supreme Court must support its determination by giving reasons for its decision.
The Court is not permitted to act as the judges acting as "personae designatae" under the provisions challenged in Wainohu were permitted to act, contrary to the characteristic judicial obligation of giving reasons to justify a judicial decision[122].
In addition, the offender is assured a full opportunity to engage in the process to determine whether or not a restriction order should be made, in contrast to the legislation considered in International Finance Trust which obliged the Supreme Court of New South Wales to proceed to make a restraining order without regard for ordinary judicial processes[123]. The legislation in question purported to direct the Supreme Court as to the manner and outcome of its exercise of jurisdiction[124].

The Lim observation was framed as an observation about the relationship between the citizen and the state under our system of government. It was made in the context of expounding an implication of the structural separation of the "judicial power of the Commonwealth" effected by Ch III of the Constitution. That structural separation constitutes "the Constitution's only general guarantee of due process"; yet its implications are "far‑reaching"[136].
The structural separation of the judicial power of the Commonwealth effected by Ch III of the Constitution had been recognised before Lim. It had come to be associated with R v Kirby; Ex parte Boilermakers' Society of Australia[137]. The structural separation operates first and foremost to restrict the legislative capacity of the Commonwealth Parliament. It implies that the Commonwealth Parliament: cannot itself exercise any part of the judicial power of the Commonwealth; cannot confer authority to exercise any part of the judicial power of the Commonwealth other than on a court; and cannot confer on a court any authority which is not part of, or incidental to, the judicial power of the Commonwealth.
The Lim observation was made in the context of examining the second of those implied restrictions on Commonwealth legislative power. The observation led in that context to the specific conclusion that, with limited exceptions, "the citizens of this country enjoy ... constitutional immunity from being imprisoned by Commonwealth authority except pursuant to an order by a court in the exercise of the judicial power of the Commonwealth"[138]. However, the import of the observation is much broader than that.
To appreciate the import of the Lim observation, and in particular to appreciate the generality of its reference to our system of government, it is necessary to begin by noting the range of courts on which the Commonwealth Parliament is permitted to confer the judicial power of the Commonwealth and in respect of which the Commonwealth Parliament is correspondingly restricted from conferring non-judicial power. Those courts are not confined to the High Court[139] and other federal courts created by the Commonwealth Parliament[140]. They encompass all State courts[141], together with all Territory courts[142]. In short, they encompass all courts in Australia.
A "court" within the meaning of Ch III is an institution for the administration of justice[143]: "an independent and impartial tribunal"[144] having the institutional capacity to exercise "the power which every sovereign authority must of necessity have to decide controversies between its subjects, or between itself and its subjects, whether the rights relate to life, liberty or property"[145] through a fair and transparent judicial process the outcome of which is determined by the application of law as ascertained to facts as found[146]. Because the separated judicial power of the Commonwealth cannot admit of "different grades or qualities of justice"[147] depending on which court in Australia is administering it, the legislative capacity of the Commonwealth Parliament to confer the judicial power of the Commonwealth on all courts in Australia implies that every court in Australia must meet and maintain the standard of institutional integrity requisite of any court having the capacity to exercise it.
Hence, a secondary operation of Ch III, which came to be recognised after Lim and to be associated with Kable v Director of Public Prosecutions (NSW)[148], is as an implied restriction on the legislative capacities of State Parliaments and Territory legislatures. The restriction has application in relation to the permissible structure of State and Territory courts[149]. The restriction likewise has application in relation to the content[150] and manner of exercise[151] of the State and Territory jurisdiction that can be conferred on State and Territory courts.
As Kable was explained in Forge v Australian Securities and Investments Commission[152]:

The derivative nature of the relationship between the Kable restriction and the Boilermakers restriction logically entails that a State or Territory law will not transgress the Kable restriction if a Commonwealth law in the same terms would not transgress the Boilermakers restriction[156]. The derivative nature of the relationship correspondingly entails that the converse does not hold: to conclude "that a State [or Territory] law does not infringe the principles associated with Kable does not conclude the question whether a like Commonwealth law for a Ch III court would be valid"[157]. That is because a State or Territory law can confer on a State or Territory court a non-judicial power, provided always that the non-judicial power is compatible with the institutional integrity of that court as a repository of federal jurisdiction; whereas a Commonwealth law cannot confer a non-judicial power on any Australian court, even if that non-judicial power is compatible with the institutional integrity of that court as a repository of federal jurisdiction[158].
The Kable restriction on State and Territory legislative power and the Boilermakers restriction on Commonwealth legislative power have a common purpose and complementary operation. If the Commonwealth Parliament could not itself confer a function on a court as an incident of the judicial power of the Commonwealth, the reason why the function lies beyond the power of the Commonwealth Parliament to confer on that court can inform determination of whether the function is properly characterised as incompatible with the institutional integrity of a court so as to be also beyond the power of a State Parliament or Territory legislature to confer on a State or Territory court[159]. In particular, if a function is not judicial for the reason that its conferral on a court would impair the integrity of that court as an institution for the administration of justice, not only must that function for that reason lie beyond the power of the Commonwealth Parliament to confer on any Australian court, but the same function for the same reason must lie beyond the power of a State Parliament or Territory legislature to confer on any State or Territory court.
That leads to the proposition that if a function is non-judicial for the reason that having that function would impair the institutional integrity of a court, legislative conferral of that function must be offensive to the Kable restriction on State and Territory legislative power in the same way as it is offensive to the Boilermakers restriction on Commonwealth legislative power. In respect of a non-judicial function of that nature, the Boilermakers restriction and the Kable restriction are indistinguishable.

That brings me to the content of the Lim observation and to the significance of that observation to what was described in Forge as an "important element ... in the institutional characteristics of courts in Australia", being "their capacity to administer the common law system of adversarial trial"[160].
The Lim observation "has its foundation in the concern for the protection of personal liberty lying at the core of our inherited constitutional tradition", and needs to be understood in the context of liberty having been recognised as "the most elementary and important of those basic common law rights, which traditionally, and therefore historically, are judged by that independent judiciary which is the bulwark of freedom"[161].
The observation was introduced within the structure of the joint reasons in Lim by the notation that the adjudgment and punishment of criminal guilt is the "most important" of the functions "which, by reason of their nature or because of historical considerations, have become established as essentially and exclusively judicial in character". From that characterisation of the function as exclusively judicial, it was noticed to follow that, consistently with the Boilermakers restriction on Commonwealth legislative power, the Commonwealth Parliament could not confer the function other than as part of the judicial power of the Commonwealth on a court[162].
Why the adjudgment and punishment of criminal guilt has always been characterised as an exclusively judicial function, as I have said in the past, "is founded on deeply rooted notions of the relationship of the individual to the state going to the character of the national polity created and sustained by the Constitution"[163]. Bearing in mind that "[m]any of our fundamental freedoms are guaranteed by ancient principles ... which are so much part of the accepted constitutional framework that their terms, if not their very existence, may be overlooked until a case arises which evokes their contemporary and undiminished force"[164], I recognise that the nature of the relationship to which I referred cannot be taken for granted and calls for further elaboration[165].
Now attempting to provide that further elaboration, I hesitate to use the language of "the rule of law". The language can become hackneyed and the profoundness of the constitutional values encapsulated within it can be diminished by over-theorisation. Still, the essence of the relationship between the individual and the state underpinned by the commitment of the function of adjudging and punishing of criminal guilt exclusively to courts has to be acknowledged to have been a core component of Albert Venn Dicey's prototypical exposition of the "rule of law"[166] which came to prominence in the final decade of the nineteenth century when the Constitution was in the process of formation.
Expressed in Dicey's words, the essence of the relationship between the individual and the state under our system of government is that the individual is "ruled by the law, and by the law alone" such that the individual "may with us be punished for a breach of law, but ... for nothing else"[167]. Notably, those exact words were quoted in the joint reasons for judgment in Lim[168] in support of the canonical observation.
The import of the Lim observation can only be fully appreciated having regard to the standard incidents of the common law system within which that exclusive judicial function of adjudging and punishing criminal guilt has historically been performed[169]. Those standard incidents have long been that "[t]he judiciary is called on ... to hear and authoritatively determine a controversy about an existing liability of the individual which is claimed by the executive [as the representative of the state] to arise solely from the operation of some positive law on some past event or conduct" as a result of which "[d]eprivation of the liberty of the individual occurs only if the determination of the controversy is by conviction" and then "only through the judicial pronouncement of a sentence which reflects the penal consequence prescribed by law for the liability determined by the conviction to have arisen from the operation of the positive law on the past event or conduct"[170].
Those standard incidents reflect what Dixon and Evatt JJ described in R v Federal Court of Bankruptcy; Ex parte Lowenstein[171] as a "long course of development" that "produced a conception of the judicial process which placed the court in the position of a detached tribunal entertaining and determining civil and criminal pleas brought before it". "It is true that in relation to contempt of court the courts of justice are armed with powers of summary punishment, at all events for contempts in facie curiae exercisable ex mero motu", their Honours added, "[b]ut this has always been regarded as an exceptional power based on the necessity of keeping order and of preserving the court from actual interference in the discharge of its duties".
The constitutional characterisation of the function of adjudging and punishing criminal guilt as exclusively judicial, and therefore as able to be performed only by a court other than in an exceptional case, is obviously protective of individual liberty in the procedural sense of preventing detention in custody at the initiative of the state other than through the agency of an independent and impartial tribunal according to a fair and transparent process. But the deeper and broader import of the Lim observation is to be found in the standard incidents of the common law system of adversarial trial protecting individual liberty in the substantive sense of allowing for detention in custody at the initiative of the state only where detention in custody is the penal consequence prescribed by law for an existing criminal liability determined to have arisen from the operation of positive law on past events or conduct[172].
That substantive constitutional significance of consigning the function of adjudging and punishing criminal guilt exclusively to the judicial branch of government is the central contribution that our common law system of adversarial trial has made to establishing and maintaining the relationship between the individual and the state within our inherited conception of the rule of law. Although rarely articulated, and all too readily overlooked, it lies at the heart of our system of government.
The Lim observation spelt out that the relationship between the individual and the state protected by Ch III is a relationship within which freedom of the individual from involuntary detention by the state, other than as a penal consequence prescribed by law for an existing criminal liability determined to have arisen from the operation of positive law on past events or conduct, is the norm. Exceptional cases have always existed and can be expected always to exist. The plurality in Lim was careful both to acknowledge the inevitability of exceptional cases and to avoid seeking to bring them within a closed category. Much more, however, was the plurality in Lim at pains to emphasise their exceptionality.
Other than in what is truly an exceptional case, and other than as an incident of the adjudgment and punishment of criminal guilt, conferral on a court of a function that involves the creation of a liability to detention in custody through an act of adjudication is not simply antithetical to the character of that court as an institution for the administration of justice. Conferral of such a function is antithetical to the very conception of justice which it is the responsibility of courts to administer.
The significance of the Lim observation for present purposes is therefore that legislative conferral on a court of a function that involves the creation of a liability to detention in custody through an act of adjudication other than as an incident of the adjudgment and punishment of criminal guilt must infringe both the Boilermakers restriction on Commonwealth legislative power and the Kable restriction on State and Territory legislative power, unless conferral of that function can be justified as within a category of exceptional case. That is so irrespective of whether the function can be performed in accordance with a judicial process.
That understanding of the significance of the Lim observation to the Kable restriction on State and Territory legislative power is underscored by the significance attributed to the observation by each member of the majority in Kable in holding invalid a State law purporting to confer jurisdiction on a State court to order the continuing detention of a named individual. The observation was "applied as a step in the reasoning" of two members of the majority[173] and was "reflected" in the reasoning of two other members of the majority[174].
The upholding by the majority in Fardon v Attorney-General (Qld)[175] of the conferral on a State court by a State Parliament of a function of creating a liability to be detained in custody in order to safeguard against a "serious danger to the community" arising by reason of "an unacceptable risk" that the individual would commit "an offence of a sexual nature ... involving violence [or] against children" is explicable on the basis of the conferral of that function having been within a category of exceptional case so as not to have infringed the Kable restriction. The conferral was characterised by Gleeson CJ in the language of Deane J in Veen v The Queen [No 2][176] as an incident of an "acceptable statutory system of preventive restraint to deal with the case of a person who has been convicted of violent crime and who, while not legally insane, might represent a grave threat to the safety of other people by reason of mental abnormality if he were to be released as a matter of course at the end of what represents a proper punitive sentence"[177].
The upholding by the majority in Minister for Home Affairs v Benbrika[178] of the conferral on a court by the Commonwealth Parliament of a function of creating a liability to be detained in custody in order to protect the community from "an unacceptable risk" of a "serious" offence relating to terrorism is similarly explicable on the basis of the conferral of that function having been within a category of exceptional case so as not to have infringed the Boilermakers restriction. I will say something more about Benbrika in the context of addressing the identification of an exceptional case.

Within the principle so formulated, the term "legitimate" is an important qualifier. As elsewhere in constitutional analysis[186], the term signifies a need for compatibility with the constitutionally prescribed system of government. Used to qualify "non-punitive", the term serves to emphasise that a legislative objective sought to be pursued by means of involuntary detention is not automatically to be accepted as compatible with the constitutionally prescribed system of government merely because that objective can be characterised as non-punitive.
Elaborating on the principle formulated by Gummow J in Kruger, with particular reference to the subsequent analysis of Gummow J in Fardon[187], I sought to explain in Benbrika why mere prevention of the commission of a criminal offence cannot be a legitimate non-punitive objective whilst acknowledging that protection from harm can be a legitimate non-punitive objective if the harm sought to be protected from by preventing the commission of the offence can be characterised as grave and specific[188].
My reasoning in Benbrika did not deny that, under our system of government, it is for the legislative branch of government to prescribe the severity of the punishment that can be imposed by a court where an existing criminal liability is determined by a court to have arisen from the operation of positive law on past events or conduct. My reasoning cast no doubt on the proposition that "[i]t is distinctly the province of the legislature to gauge the seriousness of what is seen as an undesirable activity affecting the peace, order and good government of the [polity] and the soundness of a view that condign punishment is called for to suppress that activity"[189].
The burden of my analysis in Benbrika was rather to discern and put into words a principled basis for the identification of a legitimate non-punitive legislative objective such as might be capable of justifying the conferral on a court of the extraordinary function of creating a liability to detention in custody in order to prevent a criminal offence from being committed in the future.
To accept prevention of the commission of a criminal offence in the future to be capable of justifying conferral on a court of the function of creating a liability to detention, without a requirement for the criminal offence to be capable of giving rise to grave and specific harm if committed, it seemed to me, would be to admit of the extraordinary becoming the ordinary - the exception becoming the rule. To concede to a legislature an unconstrained choice as to which criminal offences are to be treated as capable of giving rise to harm of sufficient magnitude or "seriousness" to justify conferral of such a function on a court, it seemed to me also, would be to admit of the same result.
To any suggestion that such a result ought to be excluded from constitutional analysis as a "distorting possibility"[190], two responses are appropriate. One is to recall the lesson of history that "[t]he preventive function of government ... is far more liable to be abused, to the prejudice of liberty, than the punitory function" given that "there is hardly any part of the legitimate freedom of action of a human being which would not admit of being represented, and fairly too, as increasing the facilities for some form or other of delinquency"[191]. The other is to observe the contemporary trend towards expansion in the range of offences legislatively designated to be sufficiently "serious" to justify preventive detention that can be seen in the sequence of cases beginning with Kable and moving on to Fardon, to Benbrika, and now to the present case.
So it seemed to me at the time of the decision in Benbrika; so it seems to me now. To accept without qualification that prevention of the commission of a criminal offence in the future is an objective capable of justifying the conferral on a court of the function of creating a liability to detention in custody would be to permit the Lim exception to hollow out the Lim norm. That outcome would alter in a fundamental respect the nature of the relationship conventionally understood to exist between the individual and the state under our inherited conception of the rule of law. I cannot regard that outcome as permissible within our constitutional structure.
Revisiting Benbrika with the benefit of argument in this appeal, I adhere to the principle formulated by Gummow J in Kruger as I there elaborated it. I am persuaded by the argument of the appellant that its acceptance is not precluded by the holding in Benbrika that the legislation there in issue did not infringe the Lim restriction on legislative power and that the difference between the majority and the minority can be seen to have turned on a difference in preparedness to accept the gravity of the harm sought to be protected against across the range of terrorism offences legislatively designated as "serious".
Explaining the Lim exception, the plurality in Benbrika said that it is "the protective purpose that qualifies a power as an exception to a principle that is recognised under our system of government as a safeguard on liberty". The plurality emphasised that a non-punitive purpose is "essential" but would not "suffice" to engage the Lim exception and further emphasised that as a "matter of substance, the power must have as its object the protection of the community from harm"[192]. As to the gravity of the requisite harm, the conclusion of the plurality that there was "no principled reason for distinguishing the power of a Ch III court to order that a mentally ill person be detained in custody for the protection of the community from harm and the power to order that a terrorist offender be detained in custody for the same purpose" was expressly premised on the assessment that "[t]errorism poses a singular threat to civil society"[193] and was the result of the reasoned satisfaction of the plurality that the legislation in issue was "rightly characterised as directed to ensuring the safety and protection of the community from the risk of harm posed by the threat of terrorism"[194].

"The Constitution is a political instrument. It deals with government and governmental powers"[195]. But the Constitution is also supreme law and, axiomatically[196], "[i]t is, emphatically, the province and duty of the judicial department to say what the law is"[197]. Making contestable judgments of degree is inescapable in constitutional adjudication[198]; it is a judicial responsibility.
If the foregoing analysis is correct, then it must be accepted that assessment of the gravity of harm sufficient for protection from the harm to be characterised as a legitimate non-punitive objective, capable of justifying legislative conferral of a power of involuntary detention outside the Lim norm, is a judgment of that nature. The judgment falls to be made with an eye on history, including recent history[199], cognisant of the consequences of departing from the Lim norm other than in truly exceptional cases, and mindful of the need in recognising exceptional cases to avoid what has been called "the domino method of constitutional adjudication ... wherein every explanatory statement in a previous opinion is made the basis for extension to a wholly different situation"[200].
Embracing that responsibility in the present case, I cannot accept that the offences of robbery and assault with intent to rob[201] are capable of giving rise to harm of sufficient gravity to justify conferral on a court of a function of creating a liability to detention in custody in order to "ensure adequate protection of the community against an unacceptable risk"[202] of their commission.
Never have robbery and assault not been offences known to the law. Never has loss of either life or liberty not been a penal consequence prescribed by law for their commission.
Neither offence, of course, is victimless: each involves the use or threat of violence to a person or to property. Yet in the gravity of the harm it has potential to cause, neither offence is analogous to an offence of a sexual nature involving violence or against a child as in Fardon, or to an offence relating to terrorism as in Benbrika.
If robbery is an offence protection from harm from which is sufficient to justify empowering a court to order pre-emptive detention in custody, it needs to be asked: what offence is not?
Unless the observation in Lim is to be treated as no longer descriptive of our system of government, a State or Territory law purporting to empower a State or Territory court to order detention in custody merely to ensure adequate protection of the community against an unacceptable risk of harm from robbery must contravene the restriction on State and Territory legislative power recognised in Kable just as a Commonwealth law in the same terms must contravene the restriction on Commonwealth legislative power recognised in Boilermakers.
In the result, I would allow the appeal and make the consequential orders proposed by Gordon J.
GORDON J. This case concerns a preventive detention regime - the High Risk Serious Offenders Act 2020 (WA) ("the HRSO Act") - in relation to the offence of "robbery"[203]. It raises a question, fundamental to the rule of law in a democratic society, about whether, consistently with Ch III of the Constitution, the judiciary, as the protector of the liberty of the individual, may deprive an individual of their liberty, not to punish them for a crime committed but to prevent the prospect of a further offence based on an individual's propensity to commit robbery.
Under the HRSO Act, which authorises the coercive and preventive detention of individuals, the Supreme Court of Western Australia is the key player. Insofar as that regime concerns the offence of robbery, the role of the Supreme Court is contrary to Ch III of the Constitution - its role is antithetical to its status as an institution "established for the administration of justice"[204].
The premise of the HRSO Act is that those who have offended may offend again. Detention - imprisonment - of any individual protects society from anything and everything that that individual might do if at large in society[205]. Labelling the HRSO Act scheme, and the role of the Supreme Court, as "preventive justice" is a misnomer. It is not justice. The HRSO Act scheme, at least in its operation with respect to robbery, is contrary to Ch III and undermines the two key rationales - or constitutional values - underpinning Ch III's strict separation of Commonwealth judicial power from executive and legislative power: first, the historical judicial protection of liberty against incursions by the legislature or the Executive; and second, the protection of the independence and impartiality of the judiciary so as to ensure that the judiciary can operate effectively as a check on legislative and executive power[206].
Before addressing Ch III of the Constitution, liberty and punishment, four matters should be addressed at the outset.

First, "preventive justice"[207] (use of "coercive preventive measures"[208]) is not a new concept; it is a concept with "over two hundred years of history"[209]. But it is important to understand what "coercive preventive measures" seek to achieve and how. They have two aspects: they are not only preventive, they are coercive. "[A] measure is preventive if it is created in order to avert, or reduce the frequency or impact of, behaviour that is believed to present an unacceptable risk of harm"; and "[i]t is coercive if it involves state‑imposed restrictions on liberty of action, backed by a coercive response, or the threat of a coercive response, to the restricted individual"[210] (emphasis added). The HRSO Act scheme contains both aspects. Although the HRSO Act authorises the making of two different types of coercive preventive measures, both referred to as "restriction order[s]"[211] - which is defined to mean a "continuing detention order"[212] or a "supervision order"[213] - it is sufficient for present purposes to focus on the validity of the HRSO Act insofar as it authorises the making of a continuing detention order. There was no dispute that the supervision order regime cannot be severed from the continuing detention order regime - they are inextricably intertwined and cannot be disentangled by severance[214].
Second, this proceeding is the latest in a series of cases[215] involving challenges to the validity of coercive preventive justice regimes on the basis that the regimes infringed Ch III of the Constitution. Other than in Kable v Director of Public Prosecutions (NSW)[216] and South Australia v Totani[217], in each of those cases the Court upheld the validity of the impugned regimes[218]. Some of the regimes considered by the Court involved post‑sentence continuing detention[219]; others involved restrictions on liberty falling short of detention in custody[220]. They are not all alike[221].
Third, propositions embraced incrementally by this Court in those decisions (since Kable[222]) have led to coercive preventive justice regimes becoming "an increasingly prominent feature of lawmaking in Australia"[223] and to Parliaments adjusting the design of such regimes to be more far-reaching and intrusive[224]. Regimes which once were seen as exceptional measures to address specific community fears about particular kinds of crime - terrorism or serious sexual offences - now risk becoming the norm[225], and extending to protect the community against the commission of a broad category of offences and conduct where the nature and extent of the harm that may be caused to persons or property by the prospective commission of an offence varies widely[226]. And that is not without danger. Where risk comes to prevail as the main driver of policy, there is a danger of "the logic of risk reduction ... permit[ting] ever more intrusive and liberty‑eroding incursions"[227]. As John Stuart Mill warned in 1859, "[t]he preventive function of government ... is far more liable to be abused, to the prejudice of liberty, than the punitory function"[228].
That leads to the fourth observation: the potential normalisation of regimes that override individuals' liberty on the grounds of legislatively asserted "preventive" or "protective" imperatives, unrelated to the adjudgment and punishment of criminal guilt, inevitably presents risks to the institutional integrity of courts - institutions established for the administration of justice[229] - and the separation of powers. The coercive preventive justice regimes that are enacted must reflect and respect the two key rationales - or constitutional values - that underpin, and are protected by, Ch III's strict separation of federal judicial power[230]. Those core constitutional values - "conventions of [the] 'rule of law'" - cannot be waived or set aside for the protection of the community against what is asserted to be a "growing number of 'predators'"[231], relevantly in this case: (a) persons convicted of a "serious offence"[232] (whether robbery[233] or another "serious offence") who pose an unacceptable risk of committing a robbery in the future[234]; and (b) persons convicted of robbery who pose an unacceptable risk of committing a "serious offence" in the future (whether robbery or another "serious offence").

It is the Executive that executes the laws made by the Parliament[240]. In the criminal law context, the Executive is responsible for law enforcement[241], policing and detecting crime[242], preventing the commission of crime to the extent possible[243] and executing sentences imposed by courts as punishment for criminal offences[244]. It is the Executive that has the skills and professional habits to undertake those functions.
Adjudgment and punishment of criminal guilt, on the other hand, is an exclusively judicial function[245]. Although judicial power is not susceptible to an exhaustive or exclusive definition[246], it is at its core "the power which every sovereign authority must of necessity have to decide controversies between its subjects, or between itself and its subjects, whether the rights relate to life, liberty or property"[247]. The standard incidents of the exercise of judicial power in the adjudgment and punishment of criminal guilt for an offence are "founded on deeply rooted notions of the relationship of the individual to the state going to the character of the national polity created and sustained by the Constitution"[248]. As Gageler J explained in Minister for Home Affairs v Benbrika[249], in the "[t]rial of an individual for an offence at the instigation of the executive, whether by jury or by judge alone, ... [t]he judiciary is called on ... to hear and authoritatively determine a controversy about an existing liability of the individual which is claimed by the executive to arise solely from the operation of some positive law on some past event or conduct". It is only if the determination of the controversy is by conviction that the individual may be deprived of their liberty pursuant to judicial pronouncement of a sentence[250].
Those characteristics of "judicial power" and of the judiciary (the institution qualified to exercise it) "are deeply rooted in a tradition within which judicial protection of individual liberty against legislative or executive incursion has been a core value"[251]. The Court, therefore, must be cognisant of, and vigilant to protect against, laws that are corrosive to or erode those key rationales - or constitutional values - underpinning the separation of judicial power. That cognisance and vigilance is not limited to laws that involve some overt or "outright conscription"[252] of the judiciary to do the work of the legislative or executive branches of government. The Court must be cognisant of, and vigilant to protect against, "the creeping normalisation of piecemeal borrowing of judicial services to do the work of the legislature or the executive" that gradually erodes judicial independence[253].

It is the two key rationales - or constitutional values - that underpin and are protected by Ch III's strict separation of federal judicial power that are reflected in the principle articulated in Chu Kheng Lim v Minister for Immigration, Local Government and Ethnic Affairs[254]. For present purposes, the central principle derived from Lim "is that involuntary detention in custody by the State is inherently penal or punitive in character, and thus cannot be imposed other than as an incident of adjudging and punishing criminal guilt unless one of the recognised exceptions applies; '[it] exists only as an incident of the exclusively judicial function of adjudging and punishing criminal guilt'"[255].
Where a law authorises detention in custody, the "default characterisation" is that the detention is penal or punitive[256]. What is punitive in nature about involuntary detention is the deprivation of liberty[257]. And it is the involuntary deprivation of liberty by itself that ordinarily constitutes punishment[258]. "Punishment is punishment, whether it is imposed in vindication or for remedial or coercive purposes. And there can be no doubt that imprisonment ... constitute[s] punishment"[259].
There are some exceptional cases where detention other than as punishment for breach of a law may be authorised, such as in the context of mental illness or infectious disease, or to secure attendance at trial for an offence[260]. Another exceptional category, reflected in the outcome in Lim[261], is executive detention, pursuant to statutory power, of a person unlawfully in Australia, pending either expulsion from Australia or grant of permission to remain in Australia. It may be accepted that the exceptions do not fall within "precise and confined categories"[262] and that the categories of exceptional cases are not closed[263].
Reflecting "both the strict separation of Commonwealth judicial power from executive and legislative power inherent in the text and structure of the Constitution and the values protected by that separation"[264], exceptional cases aside, "the involuntary detention of a citizen in custody by the State is permissible only as a consequential step in the adjudication of criminal guilt of that citizen for past acts"[265]. That is a limitation on power inherent in the division of powers[266].
In Benbrika[267], the plurality stated that "[i]t is the protective purpose that qualifies a power as an exception to a principle that is recognised under our system of government as a safeguard on liberty". But, consistently with Ch III of the Constitution, that cannot mean that any protective purpose, even when accompanied by a form of judicial process[268], justifies the imposition of preventive detention as "exceptional". Nowhere in Lim was it suggested, expressly or impliedly, that the exceptional category of cases where detention other than as punishment for breach of a law may be authorised extended generally to laws with a purpose of protecting the community from harm[269]. The imposition of punishment for criminal wrongdoing is and must be subject to clear limits that protect the liberty of the individual from the exercise of one of the most extreme forms of public power. Preventive detention has the same punitive consequences and effects on the liberty of the individual as detention in custody as punishment for criminal offending and yet it is too often sought to be justified "by no more than passing reference to a poorly articulated claim that the general public has a right to protection"[270]. Neither a legislative assertion of a preventive purpose, nor the fact that it may be possible to characterise a power as having a purpose of protecting the public, can alone be determinative of compatibility with Ch III of the Constitution[271]. The plurality in Benbrika should not be understood as denying the possibility that a law with a protective purpose may "pursue that purpose in a manner incompatible with the doctrine [of separation of judicial power]"[272]. If the position were otherwise, there would be no meaningful limit on the exercise of coercive powers by the State to restrict individual liberty in the name of protection; overreach would be inevitable. The "exception" would deprive Ch III, and the separation of powers, of content[273].
There must, therefore, be a principled limit on the extent to which a "protective" purpose can qualify a power to order detention in custody as an exception to the Lim principle[274]. Legislation that confers power to constrain liberty according to what someone might do in the future lies outside the "general rule" that the exercise of judicial power settles for the future "a question as to the existence of a right or obligation, so that an exercise of the power creates a new charter by reference to which that question is in future to be decided"[275]. And while there might be strong policy reasons for courts to exercise such power[276], "[w]here an exercise of a power conferred on a court settles no question as to the existence of any antecedent right or obligation yet results in an order imposing a new and enduring restriction on liberty, some special and compelling feature ought to be found to exist for its inclusion in the category of judicial power to be justified"[277].

The HRSO Act is State legislation. Its validity depends on limits on State legislative power and, in particular, the reach of the Kable principle[278]. Chapter III does not permit of "different grades or qualities of justice" as between Commonwealth and State courts[279]. State legislation which purports to confer upon a State court "a function which substantially impairs its institutional integrity, and which is therefore incompatible with its role as a repository of federal jurisdiction, is invalid"[280].
In assessing whether legislation substantially impairs the institutional integrity of a State court or courts, regard may be had to the effect of the legislation on public confidence in the courts[281] - institutions established for the administration of justice[282], including criminal justice - and the defining characteristics of courts, including the reality and appearance of independence and impartiality[283]. There is no single comprehensive statement of the content to be given to the essential notion of repugnancy to, or incompatibility with, the institutional integrity of State courts[284]. It therefore would be futile to attempt to provide some all-embracing characterisation or taxonomy of the circumstances in which "a State law might be repugnant [to] or incompatible with the exercise of Commonwealth judicial power or the essential attributes of a State court, or what might undermine a court's institutional integrity"[285].
The Court, however, must be "attentive to creative [and incremental] ways in which State Parliaments might establish impermissible relationships between courts and the political arms of government"[286]. Otherwise, the Kable principle will be stripped of its content and impermissibly constrained in its application. The application of the Kable principle depends on underlying principle, not just on what form the laws in issue in previous cases took or what was said in those cases in the context of different legislative regimes[287].
The Lim principle (a principle developed in the context of the strict separation of Commonwealth judicial power from executive and legislative power) is not irrelevant to the assessment of whether State legislation is compatible with Ch III of the Constitution. There is no separation of powers at the State level[288]. The Kable principle is less strict than the limitations on Commonwealth legislative power derived from Ch III, in the sense that it protects the independence and institutional integrity of State courts, and that "the notions of repugnancy to and incompatibility with the continued institutional integrity of the State courts are not to be treated as if they simply reflect what Ch III requires in relation to the exercise of the judicial power of the Commonwealth"[289]. But the fact that the Kable principle has its roots in Ch III of the Constitution remains of fundamental importance[290]. Chapter III requires that the judicial power of the Commonwealth be invested only in institutions sufficiently distinct from other arms of government to answer the description of "courts"[291].

It is now established that assessments and predictions of risk to the community are not matters that are incapable of judicial evaluation[292] and that "[d]ispensation of 'preventive justice' ... is not inherently incompatible with judicial power"[293]. And, most relevantly for present purposes, as Fardon v Attorney‑General (Qld)[294] and Benbrika[295] demonstrate, post‑sentence preventive detention regimes are not, in all circumstances, contrary to Ch III of the Constitution. Neither case was challenged by the appellant, Mr Garlett.
But neither Fardon[296] nor Benbrika[297] is determinative of the validity of the HRSO Act. "[T]he constitutional validity of one law cannot be decided simply by taking what has been said in earlier decisions of the Court about the validity of other laws and assuming, without examination, that what is said in the earlier decisions can be applied to the legislation now under consideration"[298]. The Court must be wary of "domino" reasoning; "[i]t is a mistake to take what was said in other cases about other legislation and apply those statements without close attention to the principle at stake"[299].
The majority in Fardon[300] decided that a State law could validly authorise post‑sentence detention of a person serving a period of imprisonment for a "serious sexual offence"[301] who posed a serious danger to the community because there was an unacceptable risk that the person would commit a further "serious sexual offence" if released from custody, and that the judiciary could determine, pursuant to a judicial process, whether an offender was to be subject to that regime. The majority in Benbrika[302] decided that a Commonwealth law could validly authorise post‑sentence detention of a person who was serving a sentence of imprisonment for certain terrorism offences[303] who posed an unacceptable risk of committing a terrorist offence if released from custody, and that the judiciary could determine, by orthodox judicial process, whether an offender was to be subject to that regime. Both Fardon[304] and Benbrika[305] concerned legislative regimes which depended on close identification between past offending (serious sexual offences or terrorism offences) and possible future offending (serious sexual offences or terrorism offences). Each applied only to a narrow class of offenders. In Benbrika[306] the Court divided over how close the nexus between the past and possible future offending must be. The minority view was that only some future terrorism offences could justify a post-sentence preventive detention order[307].
The post-sentence preventive detention regimes upheld in Fardon[308] and Benbrika[309] should be seen as exceptional and as depending on the nature and character of the past offending for which the persons subject to preventive detention were detained in custody and on the nature and character of the possible future offending sought to be prevented by subjecting those persons to continuing detention. "Sexual offences are almost universally given special significance" in criminal justice systems[310]. Repeated serious sexual offending is often driven by psychological factors and disordered sexual attitudes[311] - some, perhaps many, paedophiles will never change[312].
Terrorism offences are defined by reference to motive - religious, political or ideological - and those motives may never change. "[A] special sort of moral outrage should be reserved for terrorist crimes, as distinguished from other homicides or acts of destruction ... [W]e put definitional pressure on our ability to articulate this sense that special outrage is appropriate for these offences"[313]. Terrorism offences "address the combination of violent destruction and political or ideological motivation which is unique to terrorism but which is largely absent from other crimes. The underlying motivation of terrorism provides a compelling, nihilistic drive to terrorists that often trumps their value of the perpetrators' own lives. It would be short-sighted to divorce these motivational contexts from the crimes themselves when they directly inform the gravity of the conduct"[314]. As the plurality in Benbrika[315] put it, "[t]errorism poses a singular threat to civil society" (emphasis added).

The HRSO Act is different. Four features of the HRSO Act are significant. First, there is a broad category of offences and conduct that may engage the coercive preventive justice regime under the HRSO Act. What constitutes a "serious offence"[316] and, correspondingly, the conduct captured by the definition of "serious offence" is very broad[317]. Second, "[t]he nature and extent of the harm that may be caused to persons or property by commission of a ['serious offence'] will vary widely"[318]. The harm sought to be protected against is not "grave and specific"[319]. Third, there is no correlation required by the HRSO Act between the nature or character of the prior offending that a person is serving a sentence of imprisonment for and the nature or character of the offence that a person is found to be at risk of committing and that a restriction order is designed to protect against, save that the offending conduct must have been identified by the Parliament of Western Australia as falling within the definition of "serious offence"[320]. Fourth, the requirements to obtain and consider reports prepared by a psychiatrist and a psychologist apply in all circumstances[321], even if there is no reason to think that psychiatric or psychological factors played any part in the offender's prior offending.
The HRSO Act goes beyond the exceptional. It can be engaged in respect of any of numerous so-called "serious offences". Not only that, but the future conduct to be considered is equally broad and, in the case of robbery, is not so exceptional as to warrant such a scheme. The judiciary is left to perform the executive function of preventing a wide range of crimes one offender at a time. And it is required to do that without identifying any underlying justification of the kind that might be identified with respect to sexual offending or terrorism - factors peculiar to the psychology of sexual offenders or the motives of terrorism offenders are wholly absent.
The potential expansion of preventive detention to address all manner and kinds of criminal offending is by no means far-fetched - it is not an extreme or distorting possibility[322]. Nor is the problem new. An example from the United Kingdom (albeit in the context of sentencing offenders, rather than post‑sentence preventive detention[323]) well illustrates the point. Section 10 of the Prevention of Crime Act 1908 (UK) provided for a court to order preventive detention of "habitual criminal[s]". Where the court passed a sentence of penal servitude and was of the opinion that by reason of the offender's "criminal habits and mode of life" it was "expedient for the protection of the public that the offender should be kept in detention for a lengthened period of years", the court could pass a further sentence of preventive detention.
A report of an Advisory Council on the Treatment of Offenders in the United Kingdom stated that "[b]etween 1908 and 1911 it had become apparent that the police, in presenting cases to the Director of Public Prosecutions for indictment as habitual criminals, were applying widely varying standards and were presenting offenders for whom preventive detention had not been intended"[324]. A 1911 memorandum by the Home Secretary recorded that the Prevention of Crime Act was intended to deal with "the persistent dangerous criminal" and not with persons who were "a nuisance rather than a danger to society"[325].
The Advisory Council relevantly observed that, after a new provision dealing with preventive detention was enacted in the Criminal Justice Act 1948 (UK)[326] several decades later, "[i]t [was] clear ... that preventive detention [had] not infrequently been imposed for relatively minor offences", including where the value of the property concerned was £10 or less[327]. The Advisory Council acknowledged that it was, to some extent, borne out that under the Criminal Justice Act it remained the "nuisances" rather than the dangerous criminals who had been the recipients of preventive detention[328]. The Advisory Council also referred to research that had "shown conclusively that the majority of preventive detainees [were] of the passive-inadequate type, feckless and ineffective in every sphere, who regard the commission of crime as a means of escaping immediate difficulties rather than a part of a deliberately anti-social way of life. Very few of them [were] of the seriously violent or aggressive type of personality"[329]. They added that it must, however, be recognised that "the community ought to be protected ... both from the dangerous criminals ... and from the more numerous offenders who practise thefts or frauds on victims who may be severely afflicted by the loss of a small sum or seriously distressed by what may rank as very minor housebreakings"[330] (emphasis added). Put simply, as that historical experience suggests, "[i]mprisonment to protect society from predicted but unconsummated offences is ... fraught with danger of excesses and injustice"[331].
"The premise which underpins making any conduct a crime is that its commission works some harm to society"[332] and, as explained, detaining a person in custody will always prevent that person from committing a crime that they would commit if released from custody. If it is permissible, consistently with Ch III, for preventive detention to be ordered to protect against an unacceptable risk that a person convicted of a "serious offence" (whether robbery or another "serious offence") in the past will commit a robbery in the future or that a person convicted of robbery in the past will commit a "serious offence" in the future (whether robbery or another "serious offence"), then what is the basis for a limitation on State legislatures extending preventive detention to any offence that involves harm or a threat of harm to a person? And where does it stop? What is the outer limit? It is difficult to see why preventive detention could not be ordered in respect of a range of property offences - for example, "theft" not in the presence of any victim and unaccompanied by any threat or act of violence or fraud. Indeed, the Solicitor‑General for Western Australia frankly acknowledged during oral argument that, on the submissions of the Attorney-General for Western Australia, "as a matter of principle", there was "probably not" any offence in the Criminal Code (WA) that could not be the subject of the preventive detention regime under the HRSO Act. That cannot be accepted.
Speaking of the HRSO Act as "protective" presents a question, not the answer. How is it protective? Is it protective in a way in which the judicial branch should and can be involved? The answer is "no". It is "no" because the HRSO Act seeks to protect against recidivism in relation to a broad range of offences.
Under the HRSO Act, "preventive justice" is punishment on the basis of a risk of recidivism or tendency to commit crime; preventive detention is being used "to deal with the problem of the persistent offender"[333]. It may be that factors such as drug and alcohol abuse commonly contribute to certain types of repeat offending behaviour which the HRSO Act regime seeks to protect the community from; but that is hardly exceptional. The preventive detention regime under the HRSO Act applies to an extraordinarily large class of potential offenders; not to "a small number of unfortunate individuals who suffer disorders which make them dangerous to others"[334]. Not all recidivist offenders are "disorder[ed]" individuals of the kind described by Gleeson CJ in Fardon[335].
Loss of liberty as a punishment is ordinarily one of the hallmarks reserved to criminal proceedings conducted in courts, with the protections and assurances that criminal proceedings provide[336]. Those assurances include that in the trial of an individual for an offence at the instigation of the Executive, "[t]he judiciary is called on ... to hear and authoritatively determine a controversy about an existing liability of the individual which is claimed by the executive to arise solely from the operation of some positive law on some past event or conduct"[337] (emphasis added). The normalisation of judicial preventive detention orders means that "the distinctive character of the judiciary as the constitutional arbiter of disputes about rights between the citizen and the State will become increasingly less distinct. Incrementally but inexorably the judiciary will be drawn ever more deeply into a process in which institutional boundaries are blurred and by which its institutional independence is diminished"[338].
That cannot be permitted because it is corrosive to - it erodes - the core constitutional values underpinning and protected by Ch III of the Constitution: the judicial protection of liberty and the protection of the independence and impartiality of the judiciary. That is not a concern limited to the exercise of Commonwealth judicial power; those values must be protected to ensure that State courts are suitable repositories of federal jurisdiction. Chapter III does not permit of different grades or qualities of justice[339], and that is especially so where the justice fundamentally affects the liberty of the individual. Indeed, it would be remiss not to acknowledge that the Justices in the majority in Kable were themselves plainly cognisant of the risks posed by State courts imposing post‑sentence preventive detention divorced from the function of adjudging and punishing criminal guilt[340]. The Court must remain vigilant to prevent those risks from materialising, whether they are "dramatic and obvious" or "small and incremental"[341].
In its operation with respect to robbery, the HRSO Act undermines the two key rationales - or constitutional values - that underpin Ch III's strict separation of federal judicial power. The HRSO Act seeks to normalise preventive detention in the custody of the State, something that must, under our constitutional system, be "exceptional". It opens the door to a general practice of preventive detention - a parallel system of "preventive justice", administered by courts that are repositories of federal jurisdiction - divorced from the administration of the criminal law, where the judiciary is the key player authorising the detention of individuals in custody by the Executive because they are "criminal types". Here, the "criminal type" was a man - Mr Garlett - who, prior to being incarcerated in November 2017, was convicted of his first offences as an adult (then aged 23) for committing burglary and robbery when he entered a home without the occupants' consent and stole, with threats of violence, $20 and a pendant necklace whilst in the presence of others, including his sister, and pretending to be armed with a handgun[342]. That is not exceptional. In its operation with respect to robbery, the preventive detention regime authorised by the HRSO Act simply comes at too great a cost to the constitutional framework required by the separation of powers and the core values protected by that framework.
The fact that, in a particular case, the Supreme Court might decide that a particular offender does not present an "unacceptable" risk of committing a serious offence or that it is not "necessary", in a particular case, to make a restriction order to adequately protect the community from an unacceptable risk, does not address or overcome the issues of principle identified above. And the conclusion that the HRSO Act in its operation with respect to robbery is invalid can, and should, be made now; it does not depend on the objective seriousness of the robbery offences in relation to which continuing detention orders are, in fact, made in future under the HRSO Act.

Notwithstanding the views of many philosophers about free will, a fundamental premise of the criminal law is that individuals have free will. An offence is generally the result of a chosen act. One of the most serious responses of the criminal law is to punish that act, and the individual choice, with imprisonment. But for many years parliaments have also permitted people to be imprisoned, by "continuing detention orders", for choices that they have not yet made, and offences that they have not yet committed. The logic of such "punitive‑preventive"[343] orders - protective punishment - "applies without respect for whether the subject is a responsible agent or not"[344].
Despite the individual injustice of such imprisonment, this Court has upheld the constitutional validity of regimes of continuing detention orders for anticipated serious sexual offences[345] and for anticipated terrorism‑related offences[346]. This appeal presents the same issue in relation to continuing detention orders made by the Supreme Court of Western Australia under the High Risk Serious Offenders Act 2020 (WA) ("HRSO Act") for anticipated robberies.
The HRSO Act authorises the indefinite imprisonment of an offender after completion of their sentence based upon an apprehension that they might commit any of a wide range of offences in the future, with maximum penalties ranging from as low as 12 months' imprisonment when tried summarily[347]. The HRSO Act could potentially lead to the imprisonment of one seventh of the entire prison population of Western Australia for offences that they have not committed[348]. But this appeal is concerned only with the validity of such continuing detention orders in their application to the offence of robbery. It is common ground that the HRSO Act will be entirely invalid in its application to robbery if the legislative provisions concerning continuing detention orders in respect of robbery are beyond the power of the Parliament of Western Australia.
It would be a basic error for this Court to conclude that there could never be any circumstances of robbery which are equivalent to the offences in the regimes that have been upheld, especially since the violence element of a serious robbery offence could itself be conduct that amounts to a serious sexual offence. Principle and respect for precedent require that the HRSO Act be recognised as consistent with the Constitution unless there are specific features of the Act in its legal or practical operation, including in relation to robberies that are objectively less serious than offences in regimes that have been upheld, that create such individual injustice as to unjustifiably compromise the institutional integrity of a court.
On the material before this Court and the proper, albeit narrow, interpretation of the HRSO Act, the limit of injustice has not been reached in the application of the HRSO Act to robbery, although it is perilously close. If I had not been satisfied that the HRSO Act, in its legal operation and (so far as can be considered on the material in this case) its practical operation, makes continuing detention orders for robbery an order of last resort in cases of the most serious robberies, then I would have concluded that the HRSO Act was invalid in its application to robbery. But on the proper interpretation of the HRSO Act and on the material before this Court, the circumstances in which the legal and practical operation of the HRSO Act permit a continuing detention order for robbery are justified and cannot be meaningfully distinguished from those circumstances related to the many serious sexual offences and terrorism‑related offences for which this Court has upheld continuing detention orders.

In its generalised application to a wide range of offences, Western Australia's approach is recent but not novel. As explained in Vella v Commissioner of Police (NSW)[351], historically English courts recognised a general power of preventive detention by orders binding over a person, subject to a pledge of money, if there was sufficient apprehension that the person's activities could breach the peace. And the Court of Chancery granted writs of supplicavit to take a person into custody to restrain anticipated breaches of the peace but "the severity of the apprehended harm that might attract Chancery's intervention increased over time"[352].
The foundational legislative innovation came in the Habitual Criminals Act 1869[353]. That legislation imposed sweeping changes to respond to the problem of recidivist criminals, including introducing post‑sentence police supervision and imprisonment of those offenders who, after release on licence, were reasonably believed by a magistrate to be "getting a livelihood by dishonest means"[354]. "Serious deficiencies in the legislation soon appeared"[355]. Following various attempts[356], the United Kingdom Parliament settled upon the model in the Prevention of Crime Act 1908 (UK)[357], which empowered courts to impose a sentence of preventive detention in addition to a sentence of imprisonment for an offender found to be a "habitual criminal".
The Prevention of Crime Act was repealed in 1948[358]. In the second reading speech of the repealing Bill, the Secretary of State for the Home Department said that preventive detention had "failed to achieve any substantial results" and that "[j]udges and juries have hesitated to make use of a procedure that looked, at any rate, as if it involved a double sentence"[359]. Nevertheless, the Criminal Justice Act 1948 (UK) implemented another version of preventive detention which included, in part, "training of a corrective character" during the detention[360].
The 1948 regime remained the subject of criticism. The 1963 Report of the Advisory Council on the Treatment of Offenders concluded that "if preventive detention were abolished and nothing were put in its place the general deterrent effect of the penal system would not be weakened to any significant extent" and, in view of "all the disadvantages of the preventive detention system", proposed that the regime be abolished in its entirety[361]. The regime was abolished in 1967 and replaced with a new scheme that included extended sentences for offences[362]. In the course of the debate and second reading speeches in the House of Commons and House of Lords, the abolished 1948 regime was described as involving "not very useful rigidity of categorisation in our prison system"[363] and as "harsh, unjust, oppressive and totally ineffective"[364]. Its abolition was said to be "long overdue"[365] and made "at long last"[366]. In 1991[367], the "unpopular friend" of the extended sentence was (temporarily[368]) "laid to rest" by provisions requiring people "to be sentenced for what they have done, not for what it is feared that they may do"[369].
Nevertheless, and yet again, preventive detention was reintroduced by the Criminal Justice Act 2003 (UK). Section 225 required the court to impose a sentence of imprisonment for public protection on a person convicted of a "serious offence" and not sentenced to life imprisonment, where it was "of the opinion that there is a significant risk to members of the public of serious harm occasioned by the commission by him of further specified offences". A serious offence was one of 65 specified violent offences and 88 specified sexual offences[370].
The sentence of imprisonment for public protection was, again, one of the most widely criticised of all categories of sentence in the United Kingdom[371]. At the time that the sentence was introduced, it was estimated that there would be around 900 prisoners serving sentences of imprisonment for public protection[372]. By November 2011, there were 6,500 such prisoners[373]. The rigidity of the regime was diluted in 2008, including with the introduction of judicial discretion[374]. It was abolished altogether in 2012[375] after being described in Parliament as "discredited"[376], "poorly understood"[377], and "something of a lottery"[378].
Concurrently with these failed experiments in preventive detention in the United Kingdom, Australian parliaments introduced preventive regimes involving detention or other restrictions on liberty. As was recognised in Vella[379], the Australian regimes were in areas concerning domestic and personal violence, problem gambling that was ancillary to domestic violence, public safety and breaches of the peace, sexual and other dangerous offenders, groups associated with criminal activity, and terrorism. One early regime was the Habitual Criminals Act 1905 (NSW)[380], which had itself been considered a "useful precedent" for the Prevention of Crime Act 1908 (UK)[381].
Two relevant features of the Habitual Criminals Act for the offence of robbery were that an order for preventive imprisonment could only be made if (i) the offender had previously been convicted of robbery on three occasions and (ii) a judge exercised their discretion to declare that the offender was a habitual criminal[382]. There was a further discretion for the Governor to direct the release of an offender who was "sufficiently reformed, or for other good cause"[383].

An essential preliminary to any assessment of the constitutional validity of the HRSO Act is the interpretation of the Act. That interpretation can be set out in a staged approach in the same manner as Vella[384]. The interpretation which follows involves a strict and narrow interpretation of the HRSO Act. It focuses upon the provisions central to the subject of the challenge on this appeal - continuing detention orders - although it is necessary to emphasise that the discretion to make an interim detention order under s 46(2)(c) should only ever be exercised when there are reasonable prospects of a continuing detention order being made and, even then, only as a matter of last resort.
Although I consider the narrow interpretation below to be the proper interpretation of the HRSO Act, if there were any doubt about any significant aspect of this interpretation then s 7 of the Interpretation Act 1984 (WA) would require that narrow interpretation to ensure that its application to robbery did not exceed legislative power.
First, ss 34 and 35 allow the State of Western Australia to apply for a "restriction order" in relation to an offender, requiring the Court to make a finding as to whether the offender is a "high risk serious offender". Since the Court must assess the risk that the offender will commit "a serious offence", the application must specify the serious offence within Sch 1 to the HRSO Act which the State alleges there is an unacceptable risk that the offender will commit[385].
Secondly, by ss 7(1) and 7(2), the Court is required to assess the level of risk that the offender will commit the specified serious offence. Before a restriction order must be made, ss 7(1) and 7(2) require the State to prove that there is "an unacceptable risk that the offender will commit a serious offence". The open‑textured criterion of "unacceptable", similar to criteria such as "oppressive", "unreasonable", or "unjust"[386], is so closely associated with notions of the "adequate" protection of the community and the "necessity" of the restriction order that it is best addressed at the third stage. The second stage can therefore be limited to an assessment of the level of risk that the offender will commit the specified serious offence.
In assessing the level of risk that the offender will commit the specified serious offence, the Court may receive, under s 84(5), an offender's antecedents or criminal record, and anything relevant in the official transcript of a proceeding against the offender. The context of s 84(5), including the requirement in s 7(3)(g) to consider an offender's antecedents and criminal record, demonstrates an intention that such tender will rarely be refused by the Court[387].
Section 84(5) is not, however, a free licence for the Court to draw conclusions about the risk of the specified serious offence from unrelated offending. The offending upon which the Court can place any weight must be relevant to establishing a pattern of behaviour, or a propensity, sufficiently proximate in time, showing a likelihood that the offender will commit the specified serious offence[388]. Before concluding that there is any real risk that the offender will commit the specified serious offence, the State will almost always need to prove that the offender has committed prior offences of the same or similar nature. Even a criminal record of numerous other serious offences might say very little or nothing about a different specified serious offence. For instance, the past commission of an offence of robbery, no matter how serious, is unlikely to reveal anything about the risk of commission of an offence of criminal damage by fire, and vice versa.
The assessment of the risk of commission of the specified serious offence is not an exercise of mathematical precision. By ss 7(3)(a) and 7(3)(b)[389], the Court must have regard to expert evidence concerning the offender including psychological and psychiatric evidence. Great caution is required in the treatment of this evidence because risk prediction for serious violence, including sexual violence, has been said to be "plagued by high false‑positive rates"[390]. Members of this Court have repeatedly emphasised the notorious difficulties in expert evidence in this area[391], including by reference to comments in literature that "[p]redictions of dangerousness have been shown to have only a one‑third to 50% success rate"[392]. Caution should be exercised in evaluating any expert evidence based on generalised psychological tools for assessment of recidivism. A fundamental premise of our criminal law is that individuals, with their vast variety of backgrounds and circumstances, should be treated based upon their own circumstances.
The expert evidence can be taken into account cautiously, but the level of the risk is ultimately a question for the judge, based upon all the evidence and all the factors in s 7(3). This includes "any other relevant matter" in s 7(3)(j), particularly any evidence given by the offender[393], as well as other restrictions imposed upon the offender (apart from imprisonment, remand in custody, or bail conditions)[394]. For instance, an otherwise substantial risk could become negligible if an offender were already subject to a post‑sentence supervision order under ss 74D and 74G of the Sentence Administration Act 2003 (WA), such as wearing an electronic monitoring device.
Thirdly, by ss 7(1) and 7(2), before a restriction order must be made the State has the onus of proving that it is "necessary to make a restriction order in relation to the offender to ensure adequate protection of the community" against an "unacceptable" risk. "Community" is defined in terms that include "any community" and is not limited to the community of Western Australia or Australia[395]. It would therefore extend to risks to regional communities within Western Australia or communities outside Western Australia, and arguably even overseas.
The requirements that the risk be "unacceptable" and that the restriction order be "necessary" to ensure "adequate" protection of the community direct attention to whether the identified risk to the community can be tolerated. That assessment must be made in light of the whole of the burden which would be placed upon the liberty of the offender by the making of a restriction order, including any standard supervision order conditions[396].
Section 7 thus requires balancing, on the one hand, the level of the risk identified at the second stage (that is, the probability of the commission of the specified serious offence) together with the magnitude of the harm associated with that risk with, on the other hand, the burden that would be placed upon the liberty of the offender by a restriction order for an offence that they have not committed[397]. Consider, for example, circumstances adapted from those of Mr Garlett, involving an offender who had a pattern of unplanned and reasonably spontaneous burglaries and robberies as a minor[398]. It would not be necessary to make a restriction order to ensure adequate protection of the community from a small to moderate risk that they might commit a robbery that is not at the higher end of seriousness, especially if that offence were unlikely to involve any actual violence[399].
Even if the balancing process favoured the making of a restriction order, it might still be unnecessary to make such an order if, for example, the Court were able to make orders under other legislation, such as post‑sentence supervision orders under the Sentence Administration Act[400]. Such orders might reduce an unacceptable risk to an acceptable one.
Fourthly, if the Court concludes that the offender is a high risk serious offender then, by s 48, the Court must make a restriction order. There are two types of restriction orders: continuing detention orders, which impose the most extreme constraint upon liberty, and supervision orders. The discretion in s 48 to choose between a continuing detention order and a supervision order preserves the basic principle of justice that detention in the custody of the State should only be ordered as a matter of last resort[401].
As to supervision orders, there is a huge range of possible conditions that deprive an offender of their liberty without custodial detention. The Court should consider the conditions that are "appropriate"[402], in addition to the standard conditions in s 30(2). The requirement of appropriateness imposes a duty on the Court to make only the additional supervision conditions required to ensure "adequate" protection of the community[403], while imposing the minimum intrusion on an offender's liberty[404].
There is, however, one substantial constraint upon the exercise of the discretion by the Court to impose a supervision order rather than a continuing detention order. By s 29, the Court cannot make a supervision order in relation to an offender unless it is satisfied, on the balance of probabilities, that the offender will substantially comply with the standard conditions of the order, including not committing another serious offence. The offender bears the onus of proof under s 29.
The onus on the offender in s 29(1) is not an impossible onus which requires negating the possibility of commission of every variant of the many listed serious offences. In an adversarial system of law, s 29(1) should be interpreted to require only that the offender establish that, with a supervision order imposed, the offender will not, on the balance of probabilities, commit the serious offence, or offences, specified in the State's application[405]. For instance, an offender who is alleged in the State's application to pose an unacceptable risk of committing dangerous driving causing grievous bodily harm need not establish that they do not pose a risk of committing a robbery.
Although it is invidious to speak of probabilities in the context of predicting human behaviour, the effect of s 29(1) is that a supervision order cannot be made, and a continuing detention order must be made, if the risk of the commission of the specified serious offence remains more likely than not after taking into account the conditions of the supervision order. Nevertheless, subject to the issues related to legislative facts discussed below, which issues were not before this Court on the appeal, a continuing detention order should be a rare order because s 30(5) permits an almost unlimited range of possible conditions beyond the standard supervision order conditions. In most circumstances, a supervision order should be able to satisfy the Court that the specified serious offence will not be committed on the balance of probabilities[406]. In addition to reporting and electronic monitoring, the long list of possible supervision order conditions includes conditions like those before the Court in Minister for Home Affairs v Benbrika[407] such as prohibitions on various associations or attending various locations, home curfew, and even, in extreme cases, home detention requirements.
For instance, in the case of an offender such as Mr Garlett, if a restriction order had been considered necessary and if the Court were not otherwise satisfied under s 29(1) that the offender would not commit the serious offence of robbery, it should only require a modicum of legal competence to identify additional supervision order conditions which would satisfy the Court on the balance of probabilities that a robbery would not be committed. Even in more extreme cases where common supervision order conditions would not be sufficient for such satisfaction, it is hard to see how, as a measure of nearly last resort, a condition of home detention could not suffice rather than custodial detention. It is noteworthy that senior counsel for Mr Garlett properly conceded that there was a "clear line" between detention in custody, under a continuing detention order, and home detention, under a supervision order. That correct concession further increases the exceptional nature of a continuing detention order.
Fifthly, although a continuing detention order is indefinite, the HRSO Act requires periodic reviews. The State is usually required to apply for a review as soon as practicable after the offender has been detained for a year, and every two years thereafter[408]. In exceptional circumstances, the offender can apply for a review of their continuing detention order[409].
The State is, in effect, required to provide ongoing justification for a continuing detention order at each review. This is because, by s 68(1)(a), the Court must rescind a continuing detention order unless it makes a finding at the review that the offender remains a high risk serious offender, a matter upon which the State bears the onus of proof[410].
On review, if the offender remains a high risk serious offender, s 68(1)(b) ensures that a continuing detention order remains an order of last resort. The discretion to make a supervision order ensures that such an order should be made, in the exercise of discretion, if it could reduce the risk that the offender will commit the specified serious offence to an acceptable level.

The Constitution preserves the existence of State courts and permits them to be vested with federal judicial power. It tolerates the courts being used as instruments of individual injustice in the pursuit of broader social purposes such as the prevention of future crime. But in a line of cases this Court has held that there is a limit to the extent to which courts can be used as instruments of injustice. The progenitor of those cases was Kable v Director of Public Prosecutions (NSW)[411].
In Kable, a majority of this Court held invalid a New South Wales law that authorised the further detention in custody of Mr Kable after his sentence of imprisonment had expired. Different reasons were given by the four members of the majority. One member of the majority, Toohey J, took a distinctly different approach from the others. His Honour's conclusion of invalidity was dependent upon his reasoning that the matter was within federal jurisdiction[412]. The first question that then arises is to identify the ratio decidendi of Kable - that is, the binding principle of law at an appropriate level of generality that can be identified from the reasons of a majority that is sufficient for the decision[413].
No sensible judge or academic author has ever supported an approach to ratio decidendi in appellate courts which requires focus upon a majority agreeing on the resolution of the case by reference to reasoning at every level of particularity. On that bizarre approach, Donoghue v Stevenson[414] would have been a dull case with a ratio decidendi concerned with dead snails in ginger-beer bottles[415]. And Kable would have no ratio decidendi. Indeed, if ratio decidendi were (erroneously[416]) thought to be the only manner in which a decision could be binding authority then Kable would not even be a binding authority. It would, on that view, be open to any counsel to seek to have this Court ignore Kable without requiring it to be overturned, and to overturn other decisions that had assumed, without argument, that the decision had a ratio decidendi. Such an approach to precedent has no merit whatsoever[417].
At the appropriate level of generality, the ratio decidendi of Kable lies in the common reasoning of all members of the majority that legislation will be invalid to the extent that it confers functions upon a court resulting in what Gummow J described as the "incongruity between the discharge of those functions and the exercise of the federal judicial power"[418]. In an integrated Australian court system which includes State courts as repositories of federal jurisdiction, this doctrine has been applied with respect to the impairment of the institutional integrity of a State court by laws that required the court to act in a manner that is incompatible with, or repugnant to, its institutional integrity[419].
The Kable doctrine is based upon a presupposition in Ch III of the Constitution that Australian courts, including federal and State courts recognised in Ch III of the Constitution and possessing, or capable of possessing, federal jurisdiction, remain institutions of justice. Australian parliaments cannot impair the institutional integrity of courts by requiring them to act in a manner that is repugnant to their institutional integrity. The notions of impairment of institutional integrity and repugnancy or incompatibility with that institutional integrity are "not readily susceptible of definition in terms which will dictate future outcomes"[420]. Nevertheless, the repugnancy must usually be in a "fundamental degree"[421]. The threshold for the impairment of such a vaguely stated constitutional presupposition must be very high.
The "defining characteristics"[422] of courts that are necessary to preserve substantially their institutional integrity exist in two dimensions. One dimension is formal. It concerns the form in which the power is generally exercised: fair rules of evidence and procedure; independence and impartiality of decision‑making; open justice and public decision‑making; and the provision of reasons for decision. These characteristics cannot always be treated as absolute requirements. For instance, without losing their character as courts: courts are sometimes closed; reasons are not given in every matter, however trivial; and procedures might in exceptional cases be unfair to one party. But the substantial impairment of a defining feature of a court can lead to it losing its character as judicial.
Under the Kable doctrine, it has been held that one defining formal characteristic of courts that cannot be substantially impaired is a court's independence or impartiality, or the appearance of such[423]. The court's institutional integrity might be substantially impaired by a requirement to exercise judicial power without important aspects of procedural fairness[424], without a duty to give reasons on important issues[425], or without an independent curial determination because the court is enlisted to give effect to executive or legislative policy[426].
The other dimension of judicial power concerns the substantive effect of the exercise of the power. This encompasses the persons over whom the power is exercised, the orders that can be made in the exercise of the power, and the conditions under which those orders can be made. Under the Kable doctrine, the institutional integrity of a court can be unjustifiably compromised where the substantive effect of the exercise of judicial power is such that power, which is judicial in its formal dimension, is exercised unjudicially. That was an essential basis for the conclusion of invalidity in Kable itself.
One strand of the reasoning of McHugh and Gummow JJ in Kable concerned deficiencies in the formal dimension of judicial power. The legislation was ad hominem, directed only to Mr Kable[427]. This gave the impression that the Court would apply rules as though it were an instrument of government policy[428]. But the formal dimension was not the central focus of the majority. A significant strand of the reasoning of every member of the majority concerned the substantive exercise of the power. The majority all held that the substantive exercise of the power was repugnant to the institutional integrity of the Supreme Court of New South Wales because the Court was required to consider depriving a person of his liberty "in a process designed to bring about the detention of a person by reason of the Court's assessment of what that person might do, not what the person has done"[429]. This was described as imprisonment "not on the basis that they have breached any law, but on the basis that ... they may do so"[430], "not for what he has done but for what the executive government of the State and its Parliament fear that he might do"[431], and "punitive in nature ... not consequent upon any adjudgment by the Court of criminal guilt"[432].

It is "fundamental for an understanding of Kable"[433] to appreciate that the Kable doctrine is distinct from the principles considered in Chu Kheng Lim v Minister for Immigration, Local Government and Ethnic Affairs[434] which are based upon the separation of powers at the Commonwealth level. At the Commonwealth level, the principle of separation of powers divides the powers that can be exercised by the Commonwealth judiciary from those that can be exercised by the Commonwealth Parliament or the Commonwealth Executive. The relevant principle in Lim, relied upon by Mr Garlett, was that punishment is generally[435] the exclusive province of the judiciary and that involuntary detention of a citizen in custody will often be punitive[436]. But that is a principle concerned with the separation of powers. It says nothing about when punishment will be so unjust that a power to impose it cannot even be exercised by the judiciary.
Mr Garlett did not dispute that the constitutional separation of powers considerations that arise at the Commonwealth level do not apply equally at the State level, so the Lim principle concerning the separation of powers does not arise in this case. Nevertheless, the character of continuing detention orders as undeserved punishment is relevant to a consideration of whether the HRSO Act in its application to robbery unjustifiably compromises the institutional integrity of the Supreme Court of Western Australia. The reasoning in Lim about the nature and character of punishment, expressed in relation to the separation of powers, can inform the answer to this different question, namely: when is power that is of a nature that is generally exclusively judicial so unjust in its operation that it cannot even be exercised by the judiciary?
There are passages in the joint judgment in Benbrika that appear to contain a premise that an order that is protective cannot also be punitive[437]. For instance, the joint judgment described the object of a continuing detention order as "community protection and not punishment" and as "protective and not punitive"[438]. If this is taken to mean that an order that is protective cannot be punitive then it is plainly wrong. It is a simple logical fallacy to reason that: (i) in some non‑punitive instances, detention is imposed for public protection, such as for psychological illness, chemical, biological and radiological emergencies, contagious diseases, and drug treatment[439]; (ii) continuing detention orders are imposed for reasons including public protection; and therefore (iii) continuing detention orders are not punitive. The same logical fallacy would suggest that sentences of imprisonment for most criminal offences are not punitive because they involve community protection considerations of specific and general deterrence.
There are also passages in the joint judgment in Benbrika that appear to draw analogies between, on the one hand, continuing detention of persons who, based upon their past conduct and the commission of past offences, it is anticipated might commit an offence and, on the other hand, detention of persons due to psychological illness or infectious disease[440]. Such analogies are, at best, strained. The detention of a person for reasons of psychological illness or infectious disease is not a sanction for behaviour, actual or anticipated. It is not a response to any choices made by the person detained. A person chooses to commit an offence. A person does not choose to suffer from psychological illness or infectious disease.
Elsewhere, however, the joint judgment in Benbrika suggested that the term "punishment" was only being used in the narrow sense of sanctioning an offender "for the offence for which [they were] sentenced" or "for the offences of which [they] had been convicted"[441]. Only in this narrow, contrived sense of punishment could the legislation considered in Benbrika be said not to be punitive. The law should, however, avoid mealy‑mouthed euphemisms. The relevant legal and constitutional sense of punishment does not require "extraordinarily narrow and formalistic reasoning"[442]. And, as explained above, preventive detention has historically been recognised for what it is. It is a form of punitive order[443]. As a matter of substance, and whether or not it is described as "coercive"[444], the continuing detention of an offender under a regime such as the HRSO Act applies a sanction to enforce a norm of behaviour[445]. It differs from traditional criminal punishment in that the sanction looks forward to future behaviour rather than backwards to past behaviour[446]. But the order is punitive.
In Lim[447], Brennan, Deane and Dawson JJ (with Gaudron J relevantly agreeing on this point) treated punishment as a matter of substance rather than form when they explained that the adjudication and punishment of criminal guilt has "become established as essentially and exclusively judicial in character". Their Honours went on to describe the concern as being "with substance and not mere form"; it was not open to the Parliament to "invest the Executive with an arbitrary power to detain citizens in custody notwithstanding that the power was conferred in terms which sought to divorce such detention in custody from both punishment and criminal guilt".
This reasoning applies, a fortiori, to detention which continues the imprisonment of an offender after a sentence has been served. Thus, in Chester v The Queen[448] this Court spoke of the "stark and extraordinary nature of punishment by way of indeterminate detention" which "permit[s] the increase of a sentence of imprisonment beyond what is proportional to the crime merely for the purpose of extending the protection of society from the recidivism of the offender". As five members of this Court recognised when considering the Queensland preventive detention legislation in Fardon v Attorney‑General (Qld)[449], the punitive character of the indefinite detention does not change according to whether it is imposed at the time of sentencing or later. That legislation was also rightly recognised as penal by both the majority and the minority of the United Nations Human Rights Committee in Fardon v Australia[450].
The fiction that continuing detention orders are not punitive is further evident in the requirement that the offender remain in a prison during the term of continuing detention. As Professor Radzinowicz observed, if preventive detention really were not punishment then "an institution for preventive detention ought to be so organized that it actually differs from [a] prison"[451]. Continuing detention orders are "enhanced repression, that is ... a punishment more severe than that envisaged by the code for the offence under trial just because of the previous, heavily marked criminal record of this category of offenders"[452]. As Winston Churchill observed, "it ought not to be imagined by the courts or by the public, that a period of prolonged confinement ... within the walls of a prison ... is not, whatever name it may be called by, a most serious addition to any other punishment"[453].
Continuing detention orders under the HRSO Act are appropriately described as "protective punishment"[454].

Legislation can require, and historically has required, courts to act for what is perceived to be the public good despite injustice to the individual before the court. As explained above, there is a long history of courts participating in, and perpetuating, the injustice of punishment by a continuing detention order to protect the public from an objectively serious offence that has not been committed and might never be committed. In Kable, the existence of this injustice was not by itself a sufficient impairment of the institutional integrity of the Court. Nor was it sufficient in Fardon or in Benbrika. In Fardon[455], six members of this Court upheld the validity of continuing detention orders for serious sexual offenders under the Dangerous Prisoners (Sexual Offenders) Act 2003 (Qld). And in Benbrika[456], five members of this Court upheld the validity of continuing detention orders for terrorism‑related offenders under s 105A.7 of the Criminal Code (Cth).
Nevertheless, as Kable demonstrates, although legislation that imposes unjust punishment for an objectively serious offence will not be invalid for that reason alone, there will come a point at which the goal of public protection cannot justify the extent of injustice and the consequent sacrifice of the court's institutional integrity. The issue, to adopt the words of the joint judgment in Benbrika[457], is whether the legislation is an "appropriately tailored scheme for the protection of the community from the harm that particular forms of criminal activity may pose". Although courts can be used as instruments of unjust punishment in order to protect the community from apprehended harm, a scheme that is not appropriately tailored will unjustifiably compromise the institutional integrity of a federal, State or Territory court by requiring the court to perpetuate individual injustice of a magnitude, and in a manner, that cannot be justified by the incremental social benefit of the law.
In my reasons in Benbrika, I considered how the point might be identified at which legislation is no longer appropriately tailored because the social purposes, such as adequate protection of the community and treatment of offenders, no longer justify the individual injustice of continuing detention[458]. One circumstance is where, based on the legal operation or practical effect of the legislation, the purposes of the protective punishment could easily be met to the same extent by reasonable alternatives which are less invasive upon liberty. Another is where the purposes of the protective punishment, assessed primarily by reference to the importance placed upon those purposes by Parliament, are slight or trivial compared with the extent of the constraint upon liberty.
Like the legislation considered in Kable, the legislation considered in Fardon and Benbrika involved the individual injustice of preventive detention for very serious offences. But unlike the legislation considered in Kable, there were few obstacles to justifying the legislation considered in Fardon and Benbrika based on the formal dimension of judicial power. As Gleeson CJ said in Fardon[459], the legislation considered in that case "authorise[d] and empower[ed] the Supreme Court to act in a manner which is consistent with its judicial character". And as I said in Benbrika[460], there were many aspects of the legislation considered in that case that required that the power "be exercised in a judicial manner".

If the HRSO Act permitted a continuing detention order for all robberies, then there would be two difficulties for justification which, at least in combination, would be likely to invalidate the Act in its application to robbery.
The first difficulty is the wide range of seriousness of robbery offences. In this respect, robbery differs from serious sexual offences and terrorism‑related offences. The serious sexual offences to which the legislation considered in Fardon responded were sexual offences involving violence or against children. And the terrorism‑related offences to which the legislation considered in Benbrika responded involved conduct "connected with action which strikes at the heart of a civilised society"[466] and which "poses a singular threat to civil society"[467]. No offence in the range of serious sexual offences or terrorism‑related offences covered by the Fardon and Benbrika legislation could be described other than as a serious offence.
By contrast, the offence of robbery, under s 392 of the Criminal Code (WA), involves stealing a thing with the use, or threatened use, of violence to a person or property in order to obtain the thing or overcome resistance to it being stolen. Although the maximum term of imprisonment for robbery in circumstances of aggravation is life imprisonment, the offence need not be serious. Towards the lowest level of seriousness, robbery could be committed in circumstances as trivial as an 18‑year‑old offender demanding possession of a $1 comic book known to be owned by his friend, by threatening to tear some of the pages if it is not permanently given by the friend to the offender. Whilst the triviality of this offence is such that it might never be charged, s 6(a) of the HRSO Act extends the application of the Act to robberies that might never be the subject of a charge.
It must be emphasised that the difficulty in justifying the application of the HRSO Act to less serious offences of robbery does not depend upon any distinction between "[p]revention of harm" and "prevention of commission of a criminal offence"[468]. The invidiousness of such a distinction is illustrated by the difficulty, perhaps absurdity, of attempting to identify which criminalised acts of assistance in the commission of terrorist offences do not involve "harm"[469]. The policy choice of the Parliament of Western Australia to treat robbery as a crime that always involves harm to the public must be respected. But, as the sentencing discretion rightly recognises, the harm might be very minimal.
The difficulty in justifying the potential application of the HRSO Act to all robberies arises because the Act could, as effectively, achieve its purposes without permitting continuing detention orders for anticipated robberies that are not objectively serious. This Court has said that the "extension of a sentence of imprisonment which would violate the principle of proportionality can scarcely be justified on the ground that it is necessary to protect society from crime which is serious but non‑violent"[470]. That reasoning applies, a fortiori, when the crime is both non‑serious and non‑violent. It is hard to conceive of any circumstances where the adequate protection of the community (including potential victims) requires the continuing detention of a person solely on the basis that it is predicted, by means of dubious validity, that the person is likely to commit a robbery at the lower end of seriousness. Further, it is at least arguable that an order for continuing detention of such a predicted offender might undermine, rather than advance, any care or treatment of that person.
A second difficulty in justifying the application of continuing detention to any offence of robbery is the apparent absence of balance between, on the one hand, the limited need to protect the community from the commission of robberies that are not objectively serious and, on the other hand, the extreme constraint upon liberty imposed by continuing detention orders.

Since the HRSO Act was very recently enacted, Mr Garlett was not in a position to make submissions about the practical operation of the HRSO Act. Nevertheless, it is necessary to observe that the practical operation of the Act may, in future, raise significant difficulties in justifying continuing detention orders, particularly as the level of objective seriousness of the "serious offences", or the level of objective seriousness of the circumstances of those offences, diminishes.
Although this Court had no legislative facts before it on the subject, one potentially significant issue in the practical operation of the HRSO Act was referred to in the written submissions for Mr Ryan. That issue is what Quinlan CJ, referring to the predecessor legislation to the HRSO Act, described as a "Catch‑22"[473]. The Catch‑22 arises where a continuing detention order must be made before the State will provide an offender with treatment, which is in turn necessary to prevent them from being subject to an order for continuing detention. That Catch‑22 would show a practical operation of the HRSO Act that is contrary to its expressed purposes. It would provide a strong foundation for a submission that the significant individual injustice manifested by the HRSO Act is unjustified by its purposes. As Quinlan CJ rightly said, it is "in the interests of the community, and its protection from offending, that an offender with known treatment needs have those treatment needs addressed before consideration is given to their release under supervision not, as is the case, afterwards"[474].
The same concern has been reiterated in proceedings under the HRSO Act. This suggests that its practical operation might, not uncommonly, be subject to the same issues[475]. In this matter, however, probably due to the recent nature of the HRSO Act, there was no evidence about these issues before Corboy J and there is insufficient information before this Court for any legislative fact to be found concerning the extent to which the Catch‑22 arises under the HRSO Act.
Another significant issue may be the disproportionate effect that the HRSO Act has on Indigenous Australians for reasons that do not bear upon any of the purposes of the HRSO Act. That effect might be manifest in relation to Indigenous Australians who do not have permanent or fixed accommodation. As the Australian Law Reform Commission has observed, "Aboriginal and Torres Strait Islander peoples are ... disproportionately represented in the homeless population ... accounting for 28% of homeless people [in 2011]"[476]. Those persons might be deprived of the possibility of a supervision order, and subjected to a continuing detention order, only because they are unable to prove, as required by ss 29(1), 30(2)(a), and 30(2)(c), that they will advise a community corrections officer of their address and every change in their place of residence during the period of the order[477].
Any disproportionate effect of the HRSO Act upon Indigenous Australians might be exacerbated by psychological or psychiatric reports to which the Court must have regard[478]. In 2019, it was observed that Australian practitioners in this field "do not have access to risk assessment instruments that have been developed and validated for Australian populations and therefore use instruments that were developed for North American and European populations". The authors continued[479]:

Since the only substantial concerns in justifying the HRSO Act in its application to robbery, on the facts of this case, relate to the legal operation of the HRSO Act, it is essential to assess those concerns in light of the proper interpretation of the HRSO Act. The five interpretive stages set out above adopt a narrow interpretation that answers these concerns. That narrow interpretation is the best understanding of the HRSO Act, which has a broad premise of depriving persons of liberty only where it is necessary to ensure adequate protection of the community. Even if the narrow interpretation were not the proper interpretation, s 7 of the Interpretation Act would require the relevant provisions to be read down in this manner in order to prevent the invalidity of the HRSO Act in its application to robbery.
Both of the issues considered above, concerning justification of the legal operation of the HRSO Act, relate to the possibility of a continuing detention order being imposed for the anticipated commission of a robbery that is not objectively serious and involves little individual or social harm. On the proper interpretation of the HRSO Act, no restriction order can be made unless, by the third stage in the interpretive process, the probability of the specified serious offence being committed, together with the magnitude or seriousness of the harm that would result, outweighs the burden placed upon the liberty of the offender by a restriction order for an offence that they have not committed.
Applied correctly, therefore, even a judicial assessment of a high probability of an offender committing a robbery would not be sufficient for a restriction order if the anticipated robbery is of a low level of seriousness. Even where an anticipated robbery is sufficiently serious to engage s 7 of the HRSO Act, any concerns arising from the lack of judicial discretion to refuse a restriction order are resolved by the fourth stage of the interpretive process. Given the vast range of possible supervision orders, including even home detention, it should not require more than a modicum of ingenuity to devise supervision orders that will suffice for an offender to establish that they will satisfy the conditions of a supervision order, including not committing the specified serious offence. A continuing detention order would not then be made.
Mr Garlett's challenge on this appeal was concerned only with continuing detention orders; supervision orders for anticipated offences of robbery would be invalid only if inseverable in the legislative scheme from continuing detention orders. An important part of the scheme is the discretion to make a supervision order rather than a continuing detention order. That discretion would almost invariably be exercised, other than in the most extreme cases which involve offenders who cannot be the subject of a supervision order. The existence of this "internal" discretion is a reasonable alternative to a discretion as to whether any restriction order should be made. And, in light of the extreme circumstances necessary for a continuing detention order, it cannot be said that the purposes of the protective punishment are slight or trivial compared with the extent of the constraint upon a person's liberty for an anticipated offence.

It is of paramount importance to these reasons to emphasise that, on its proper interpretation, the HRSO Act does not permit the imposition of continuing detention orders for any robbery. In its application to robberies, the HRSO Act permits restriction orders only for anticipated robberies with a sufficiently high degree of seriousness and a sufficiently high magnitude of harm to justify a restriction order that deprives a person of their liberty for an offence that they have not committed. Even then, the restriction order will only be a continuing detention order as a matter of last resort.
The real question on this appeal, in the absence of any particular legislative facts, is therefore whether the HRSO Act is invalid in its application to robbery in those extreme cases in which continuing detention orders would be imposed. On its proper interpretation, which involves a very narrow application of continuing detention orders, and in light of the decisions of this Court in Fardon[483] and Benbrika[484], that question must be answered in the negative. As explained at the outset of these reasons, any attempt to distinguish the seriousness of extreme cases of robbery from the sexual offences that were the subject of the legislation considered in Fardon is a futile enterprise because the categories are not independent[485].
Whether or not a continuing detention order for an offence that has not been committed can ever be morally justified, the Constitution does not prohibit the Parliament of Western Australia from empowering a court to impose that injustice in the extreme circumstances of an anticipated robbery as permitted by the proper interpretation of the HRSO Act.
I agree with the orders proposed by Kiefel CJ, Keane and Steward JJ.
GLEESON J. Legislation providing for a court to order the detention of an offender following completion of (or otherwise in excess of) a sentence of imprisonment was found to be valid in Fardon v Attorney-General (Qld)[486], Pollentine v Bleijie[487] and Minister for Home Affairs v Benbrika[488]. In Fardon and Pollentine, which concerned State legislation, the standard of constitutional validity engaged was that identified in the decision of Kable v Director of Public Prosecutions (NSW)[489], and which has been stated in terms that State (or Territory[490]) legislation may not validly confer upon a court that is a potential repository of federal jurisdiction a function that substantially impairs that court's institutional integrity, such an impairment being incompatible with the court's constitutional position as a potential repository of federal judicial power[491]. In Benbrika, which concerned Commonwealth legislation, the standard of validity engaged was instead supplied by the principle of separation of federal judicial power from the executive and legislative powers of the Commonwealth[492].
Of these decisions, Fardon is most relevant to this case. Fardon concerned the Dangerous Prisoners (Sexual Offenders) Act 2003 (Qld) ("the DPSO Act"). The appellant did not challenge the correctness of Fardon (or any other decision in which this Court has found legislation providing for preventive orders to be valid). Instead, the appellant contends that, unlike the DPSO Act, the High Risk Serious Offenders Act 2020 (WA) ("the HRSO Act") offends the Kable principle insofar as the HRSO Act applies to a person who has been convicted of robbery.
It was recognised in Fardon that the DPSO Act raised "[s]ubstantial questions of civil liberty" and "difficult questions involving the reconciliation of rights to liberty and concerns for the protection of the community"[493]. Those questions are magnified in relation to the HRSO Act to the extent that the Act has the potential to apply to more offenders and may operate to protect the community from a wider array of harms.
The present case may demonstrate the harsh potential of the HRSO Act: the State of Western Australia sought a continuing detention order from the Supreme Court of Western Australia ("WASC")[494] in respect of a young offender who has spent little of his adolescent and adult life outside of prison. His most recent imprisonment followed a conviction for aggravated armed robbery involving threats of violence but no physical violence, and no weapon but a pretence of being armed with a handgun. However, as it turned out, no continuing detention order was made. Prior to the hearing of the application, the State advised the Court that the State would seek only a supervision order[495], and, ultimately, the State's application was refused. The appellant was not considered to have a propensity to commit any particular "serious offence" as defined in the HRSO Act. Rather, the Court's conclusion was that the appellant had a tendency to commit offences more generally, particularly when in antisocial company and when under the influence of illicit substances.
In any event, and as in Fardon, this case may not be decided upon the basis of concerns about the legislative policy of preventive detention as provided for in the State legislation under challenge. The appellant argued that the case raises for consideration whether the regime in the HRSO Act, designed to protect the community, might render preventive detention so commonplace that its application by the WASC is offensive to the Court's institutional integrity. Put another way, does the HRSO Act provide for so much preventive detention that its application should be impugned as a "grossly unjudicial chore"[496]? The Court's capacity to address broad questions of this kind meaningfully is limited: its task is confined to determining the narrow issue of the validity of the HRSO Act in its application to a person who is under a custodial sentence for robbery.
I agree with the plurality that the function of the WASC under the HRSO Act in its application to the offence of robbery is materially indistinguishable from the function conferred upon the Supreme Court of Queensland ("QSC") by the DPSO Act. Accordingly, the appellant's challenge to the validity of the HRSO Act must fail. I generally agree with their Honours' reasons that the Act is not offensive to the institutional integrity of the WASC but add the following observations.

Despite early criticisms[497], the statement referred to in Benbrika by the plurality as the "Lim principle"[498] and by Gageler J in the present proceeding as the "Lim observation"[499], namely that, exceptional cases aside, "the involuntary detention of a citizen in custody by the [s]tate is penal or punitive in character and, under our system of government, exists only as an incident of the exclusively judicial function of adjudging and punishing criminal guilt"[500], is now well accepted as a statement of a constitutional limit upon Commonwealth legislative power[501]. In Benbrika, the plurality considered that a preventive detention regime imposed by Commonwealth legislation was valid as an exception to the "Lim principle"[502]. Noting that the decision in Lim itself illustrated that the categories of exceptional cases of legal non-punitive detention are not closed, the plurality in Benbrika did not accept that the exceptions were either confined by history or insusceptible of analogical development. For their Honours, it was the protective purpose of the relevant legislation that qualified the judicial power conferred by the legislation as "an exception to a principle that is recognised under our system of government as a safeguard on liberty"[503].
It has been suggested that the Lim principle operates as a limit upon the legislative power of the States, as a principle that identifies functions that are incompatible with the institutional integrity of a State court that is the concern of the Kable principle. In the absence of a challenge to Fardon, the question was not fully argued. It would be a significant step to conclude that the Lim principle operates as an additional constraint on State (and Territory) legislative power, over and above the Kable principle.
There can be no doubt that the generally penal or punitive character of involuntary detention of a citizen (or any person) in custody does not depend upon whether "the [s]tate"[504] effecting the detention is the Commonwealth, or an Australian State or Territory. Further, at least as a matter of empirical fact, it is the norm throughout Australia that involuntary detention exists only as an incident of the exercise of judicial power to adjudge and punish criminal guilt. However, the Lim principle was articulated as a constitutive part of the doctrine of the separation of Commonwealth judicial power[505], not as a doctrine about the nature of Ch III courts or the characteristics of Ch III courts that are essential to the institutional integrity of those courts, and not in answer to a question about the scope of State legislative power.
This Court in Fardon did not treat the Lim principle as relevant to the constitutional validity of the DPSO Act, despite an argument (made by the Attorney-General for the Commonwealth) that the DPSO Act would have been valid if enacted as Commonwealth legislation (thereby testing the Act against the Lim principle) and despite an argument (made by the appellant in that case) that the Act was invalid as a Bill of Pains and Penalties, because it inflicted punishment without a judicial trial[506].
Rather, the majority Justices focussed squarely on whether the DPSO Act impaired the institutional integrity of the QSC in terms of its independence and impartiality. In this regard, the judgments are consistent with the well-established separation between the Kable principle (which relevantly defines limits upon State legislative power) and the doctrine of the separation of Commonwealth judicial power (which relevantly limits Commonwealth legislative power)[507].
The common conclusion of the majority Justices in Fardon was that the DPSO Act did not impair the institutional integrity of the QSC, and so did not transgress limits imposed by Ch III of the Constitution. Further, while it is true to say that the legislation in Fardon was directed to a particular class of sexual offender, none of the majority Justices in Fardon reasoned by reference to the special nature of sexual offences, or the exceptional character of the DPSO Act as a scheme tailored to address specific community fears about sexual crimes, or its limited operation, because the legislation was directed to what might be thought to be a very small number of offenders. Nor did their Honours focus attention upon the nature of the risk assessment that the QSC was required to undertake, beyond observing that it involved an evaluative exercise that the Court was well equipped to undertake[508]. Their Honours did not express concerns about the "borrowing of judicial services to do the work of the legislature or the executive"[509], or about the potential "blur[ring]" of institutional boundaries[510].
Although not explicitly addressed to the application of the Lim principle, there are several passages in the majority judgments in Fardon that are inconsistent with the Lim principle as a test for whether State legislation offends the institutional integrity of a State court.
Gleeson CJ perceived "the case of the prisoner who represents a serious danger to the community upon release" as an "almost intractable problem" for the criminal justice system, but one which may warrant a legislative response which considers "the protection of the safety of citizens in light of the rights and freedoms accepted as fundamental in our society"[511]. The Chief Justice cited, with apparent approval, Deane J's observation in Veen v The Queen [No 2] that[512]:

Gummow J was the only Justice to address the argument that the DPSO Act could have been validly enacted as Commonwealth law. His Honour rejected that argument but, in doing so, reformulated the Lim principle in terms that, "the 'exceptional cases' aside, the involuntary detention of a citizen in custody by the [s]tate is permissible only as a consequential step in the adjudication of criminal guilt of that citizen for past acts"[520]. As his Honour put it, "[t]he vice for a Ch III court and for the federal laws postulated ... would be in the nature of the outcome, not the means by which it was obtained"[521].
Notably, Gummow J did not extrapolate from this reformulation to a conclusion that the DPSO Act was invalid. His Honour (with Hayne J here agreeing) considered that the application of the Kable principle focussed attention on the judicial process under the impugned legislation and whether elements of that process "may ameliorate what otherwise would be the sapping of the institutional integrity of the Supreme Court"[522]. Gummow J did not express any doubt about the impact of the DPSO Act upon either the independence or the impartiality of the QSC. Ultimately, his Honour considered that the nature of the "factum" selected for the attraction of the Act (being a "prisoner"), the subjection of orders to annual "review", the judicial nature of the process with respect to applications, and the Court's independence in the performance of its functions under the Act, combined to support the conclusion that invalidity was not established[523].
Hayne J (who otherwise agreed with Gummow J) reserved his opinion about whether federal legislation along the lines of the DPSO Act would be invalid[524]. His Honour explicitly adverted to the problem that preventive detention "is at odds with identifying the central constitutional conception of detention as a consequence of judicial determination of engagement in past conduct"[525]. However, his Honour saw this as an issue about judicial power for the reason that legislation requiring a federal court to make an order for preventive detention "would purport to confer a non-judicial function on that court"[526].
For their part, Callinan and Heydon JJ stated[527]:

Although in Fardon Gummow J noted that the Lim principle had informed several of the judgments in Kable (including his own)[528], there is reason to doubt its significance for the principle stated in Kable, at least for the purpose of a conclusion that the Lim principle is germane to the institutional integrity of a State court. In Kable, his Honour considered that the requirement of the Community Protection Act 1994 (NSW) ("the NSW Act") that the Supreme Court of New South Wales ("NSWSC") "inflict punishment without any anterior finding of criminal guilt by application of the law to past events, being the facts as found" was "repugnant to judicial process"[529]. However, his Honour was alone in apparently treating that feature of the NSW Act as a sufficient basis for the challenged legislation's incompatibility with the institutional integrity of the NSWSC[530].
The other Justice who referred explicitly to the Lim principle in Kable was Toohey J, but his Honour reasoned materially differently by rejecting the NSW Act, including because preventive detention under the Act: was not an incident of the exclusively judicial function of adjudging and punishing criminal guilt; was not part of a system of preventive detention with appropriate safeguards, consequent upon or ancillary to the adjudication of guilt; and did not fall within the "exceptional cases" mentioned in Lim, directly or by analogy[531]. These reasons, and in particular his Honour's evident acceptance of the possibility of "appropriate safeguards", do not indicate that Toohey J would have accepted Gummow J's reformulation of the Lim principle without qualification.
Gummow J also noted that the Lim principle was "reflected" in the reasons of Gaudron J and McHugh J in Kable[532]. But neither Justice can be taken to have expressed any general view that State legislation providing for court-ordered preventive detention after sentence, directed to a class of offenders and for a purpose of community protection, was likely to be invalid for repugnancy to the judicial process. While Gaudron J considered that the process provided for by the NSW Act was the "antithesis of the judicial process", her Honour emphasised the Act's provision for formation of an opinion as to the probability of future offending "on the basis of material which does not necessarily constitute evidence admissible in legal proceedings"[533], and concluded that public confidence could not be maintained in a judicial system not predicated on equal justice - an observation directed to the ad hominem nature of the NSW Act[534].
In Kable, McHugh J had stated that "there is no reason to doubt the authority of the State to make general laws for preventive detention when those laws operate in accordance with the ordinary judicial processes of the State courts"[535]. In Fardon, McHugh J explicitly deprecated the phrase "repugnant to the judicial process" as tending to invite error[536]. McHugh J concluded that repugnancy to the traditional judicial process "will seldom, if ever, compromise the institutional integrity of [a State court] to the extent that it affects that court's capacity to exercise federal jurisdiction impartially and according to federal law"[537].

The terms of s 392 cover a wide range of offending including conduct that may not cause significant harm to any individual. Potential harms that may be inflicted by an offence against s 392 will necessarily vary according to the particular circumstances of the offence. However, it is reasonable to assume that, by fixing a maximum penalty of life imprisonment in some circumstances, the legislature apprehended that the harm inflicted by a robbery may be very grave. A court is not well placed to compare the gravity of potential harms resulting from categories of offences beyond noting the maximum penalties fixed by the legislature. If the institutional integrity of a court may be compromised by applying a law such as the HRSO Act on the basis that the harm sought to be addressed by the law is not sufficiently grave, then, having regard to the availability of life imprisonment as a maximum penalty, I am not persuaded that the institutional integrity of the WASC may be compromised by the inclusion of robbery as a "serious offence" in the HRSO Act on that account.
The HRSO Act as it applies to the Western Australian offence of robbery seeks to balance the liberty interests of both a "high risk serious offender" and those members of the community who may be harmed as a result of an "unacceptable risk that the offender will commit a serious offence"[538], particularly, although not necessarily, the offence of robbery. I respectfully agree with the observation of the plurality in Benbrika that Gummow J's analysis in Fardon did not explain why an appropriately tailored scheme for protection of the community from harm resulting from particular forms of criminal activity is incapable of coming within an "exceptional case" to be identified by analogy to those "exceptional cases" identified in Lim[539]. To my mind, such detention is capable of being seen as analogous to involuntary detention in cases of infectious disease which is necessarily directed to community protection[540]. Involuntary detention in cases of mental illness may also afford an analogy where the detention is not solely for the protection of the detainee.

Garlett v Western Australia

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