Was there an error of law?
30 It is apparent that in his process of reasoning, the Minister understood the law to be that, by the operation of ss 189 and 196 of the Act, if the appellant was refused a protection visa and was not granted another visa he would remain in immigration detention until such time, if it arose, that he could be removed to another country. On the appeal, it was rightly accepted on behalf of the Minister that underlying his reasoning was an understanding of the law based on Al-Kateb that if the appellant's visa was refused he would be detained until he was removed to another country (T18:44-T19:11). Although unknown, and unknowable, to the Minister at that time, that was an erroneous understanding of the law because (just over a month after the Minister's decision) Al-Kateb was re-opened and overruled in NZYQ.
31 The High Court pronounced its orders in NZYQ on 8 November 2023 and published its reasons on 28 November 2023. The construction of s 196 adopted by the majority in Al-Kateb was held to be correct, but subject to s 3A of the Act, ie the Act is not to apply so as to exceed Commonwealth power. Detention of a non-citizen by the executive in circumstances where no visa application was on foot, and there was no real prospect of removing the non-citizen in the reasonably foreseeable future, was held to be inconsistent with Ch III of the Constitution and s 196 was to be read down accordingly (see NZYQ at [9]).
32 As the primary judge explained, NZYQ did not change the law; "[p]rospective overruling of authority is antithetical to basic concepts of the judicial power and thus heretical in Australia: Ha v New South Wales [1997] HCA 34; 189 CLR 465 at 503-504 (Brennan CJ, McHugh, Gummow and Kirby JJ)" (at PJ [21]). The constitutional principles elaborated in NZYQ must therefore be understood to have applied at the time of the Minister's decision.
33 In making his decision, the Minister was required to take into account the Act and its operation; he was required to take account of the legal consequences of his decision: NBMZ v Minister for Immigration and Border Protection [2014] FCAFC 38; 220 FCR 1 at [9]-[10] per Allsop CJ and Katzmann J. See also Taulahi v Minister for Immigration and Border Protection [2016] FCAFC 177; 246 FCR 146 at [84] and [88] per Kenny, Flick and Griffiths JJ in respect of the requirement that the Minister consider the "direct and immediate statutory consequences" of the decision.
34 Such a consideration inevitably required the Minister to act on a correct understanding of the Act, including its constitutional limitations. Because of the obligation of non-refoulement of the appellant, the poor prospects of his removal to a third country and the terms of the Act, at the time of the Minister's decision in this case he understood the legal consequences of the Act included "indefinite detention", but that was wrong. That was an erroneous conclusion as to the consequences of the decision because of an erroneous understanding of the Act and its operation. That is an error of law.
35 Turning to contention 1 in the notice of contention, the first point sought to be made by the Minister is that where an unlawful non-citizen is detained for the purpose of removal, ss 189 and 196 of the Act apply unless and until, as a matter of constitutional fact, there is no real prospect of removal becoming practical in the reasonably foreseeable future. That much may be accepted, but it is no answer to the alleged error. The Minister, quite rightly, considered what the legal consequences of a visa refusal decision would be for the appellant. In doing so, he formed the view, in essence, that in the event the protection visa was refused the prospects of anything other than "indefinite detention" for the appellant were poor. That view was based on a particular understanding of the Act, which is now known to be wrong.
36 The Minister's second point is that at the time of his decision, the appellant was not being detained for the purpose of his removal; rather, he was being detained for the purpose of considering and determining his application for a protection visa. Again, that much may be accepted, but it is no answer to the alleged error. The Minister was considering the consequences of a decision to refuse the appellant a protection visa, which would, immediately on the decision being made, put the appellant into the position of being detained for the purpose of his removal. The fact that prior to such a decision he was not being detained for that purpose is not to the point.
37 The Minister's third point refers to HSCK v Minister for Immigration, Citizenship and Multicultural Affairs [2024] FCA 313 in which Button J, in circumstances similar to the present, rejected the contention that the Tribunal's decision not to grant the applicant a protection visa "was affected by jurisdictional error, in that the Tribunal's conclusion that the continuing indefinite detention of the applicant was justified by the protection of the Australian community was not open to the Tribunal, as it was contrary to the decision of the High Court in [NZYQ]" (at [8], [31] and [37]).
38 However, in that case the error was not put as an error of law, but rather as an error of factual conclusion based on the law. Presumably for that reason, the judgment records the applicant's case as depending on making good the proposition that various concessions made by the Minister with regard to obligations of non-refoulement and poor prospects of removal were sufficient to bring the case within the constitutional limitation explained in NZYQ (at [26]). The applicant was unable to establish that on the facts. That inquiry does not arise on the way in which the appellant puts his argument in the present case.
39 More specifically, the Minister's notice of contention refers to HSCK at [34]. In that paragraph, Button J was explaining the factual differences between the case before her and NZYQ. In particular, her Honour observed that in the case before her "the occasion had not yet arrived to make enquiries and see whether [the applicant] could be removed to a third country, or what timeframes would be involved." Again, that much may be accepted, but it is no answer to the alleged error in this case. It is perhaps a point relevant to materiality, to which we will come, but it says little about whether the Minister made his decision on an incorrect understanding of the law.
40 The Minister's fourth point refers to TCXM v Minister for Immigration, Citizenship and Multicultural Affairs [2024] FCA 451 in which Wheelahan J, also in circumstances similar to the present case, rejected the contention, with reference to NZYQ, that "[t]he Tribunal erred in not correctly interpreting or applying the law in that it did not understand and apply the principle that indefinite detention is unlawful" (at [79] and [81]). As with HSCK, the error of law was characterised differently in TCXM to how it is put in the present case. His Honour's reasons for rejecting the argument, recorded at [81], are inapplicable to the present case.
41 The particular paragraphs of the judgment in TCXM to which the Minister refers in the notice of contention, namely [46]-[47] and [54]-[55], are not addressed to a ground alleging that the Tribunal acted upon an incorrect understanding of the law. They deal with, respectively, a legal unreasonableness ground and a ground based on the Tribunal's alleged failure to consider a relevant consideration, namely that indefinite detention is unlawful. Nothing that is said in those paragraphs detracts from our conclusion in the present case that the Minister made his decision upon an incorrect understanding of the law.
42 The Minister's fifth point is that he was not required to consider "future contingencies that might arise in the future." He refers to BNGP v Minister for Immigration, Citizenship and Multicultural Affairs [2023] FCAFC 111; 298 FCR 609 at [101] and [138]. Once again, the point addressed there was with regard to legal unreasonableness and not a ground alleging that the decision-maker acted upon an erroneous understanding of the law. There is nothing said there that detracts from our conclusion that in the circumstances of the present case the Minister did so.
43 In view of the conclusion that the Minister's reasons proceeded on an erroneous understanding of the law, his decision was made outside the jurisdiction conferred on him by s 501A(2), provided that the error was material in the relevant sense.
44 The appellant was not, however, content to leave matters there and submitted that at the error (as opposed to materiality) stage of the inquiry it is necessary to establish that the Minister failed to act on a correct understanding of the law "on a point of sufficient significance to the ultimate decision", citing Minister for Immigration, Citizenship, Migrant Services and Multicultural Affairs v CBW20 [2021] FCAFC 63; 285 FCR 667 in that regard. For the same reasons given below in relation to materiality, we are satisfied that the error was on a point of real significance to the ultimate decision. It is therefore unnecessary to enter upon the point of debate raised by the appellant.
45 That said, we observe that the Court in CBW20 did not separately consider the requirement of materiality. Its findings that the errors "were fundamental to" and were in respect of an issue that "underpinned" the decision (at [57]), that the errors were "serious[]" and had a "close connection" to the decision, and that they "played an important role" in the decision (at [59]), can be best understood as amounting to a finding that the errors were material in the requisite sense.