MZAPC: Calibrating constitutional limits on legislative power

Emily Hammond

03.06.21

The High Court's decision in MZAPC v Minister for Immigration & Border Protection [2021] HCA 17 reveals continuing differences in judicial approach to a central concept for Australian judicial review - jurisdictional error. In this post, I argue that resolution of such differences would be assisted through a change in perspective on the concept. The change? A more explicit recognition that jurisdictional error marks an important constitutional limit on the legislative power of Australian Parliaments to affect rights and obligations through executive decisions. Taking this step will not resolve all judicial disagreements about the meaning of jurisdictional error, but it may move debates onto a more productive footing.

MZAPC (Part 1)

MZAPC resolves the status, content and proof of the materiality element of jurisdictional error. 'Jurisdictional error' describes the category of legal error necessary to engage the entrenched measure of review for Commonwealth and state powers described in Plaintiff S157 and Kirk. The High Court identified a materiality precondition for jurisdictional error in Hossain (2018) and explained and applied it in subsequent decisions including SZMTA (2019). The materiality element involves a realistic possibility that an error has affected the decision, i.e. that the decision could have been different had the error not occurred. In MZAPC, all members of the Court recognise and apply a materiality precondition for jurisdictional error. All members of the Court determine that the errors in the case at hand were immaterial.

MZAPC also provides a majority ruling on proof of the materiality element. Chief Justice Kiefel, and Gageler, Keane and Gleeson JJ hold that materiality is a question of fact in respect of which the applicant for judicial review bears an onus of 'proving by admissible evidence on the balance of probabilities historical facts necessary to satisfy the court that the decision could realistically have been different ...' (at [60]). A minority (Gordon and Steward JJ (at [84]-[88]); Edelman J (at [155])) propose two steps in applying the materiality precondition: the applicant for review must identify - through a task of persuasion, rather than evidentiary onus - that an error could realistically have resulted in a different decision. If the applicant meets this task of persuasion, it becomes a matter for the respondent to establish that the error was immaterial.

As the unanimous outcome indicates, and as Edelman J observes (at [156]), the difference in approach to the materiality inquiry may often have little practical effect. Yet it is difficult to ignore the strongly articulated judicial differences on matters of principle in MZAPC. To return to the theme of this post – clarity in doctrinal issues of the kind debated in MZAPC might be assisted by reevaluating the constitutional significance of jurisdictional error in the context of Ch III's exhaustive scheme for the exercise of judicial power in federal matters.

Ch III and the limits of legislative power to affect rights and obligations through decisions of non-courts

When it comes to government decisions concerning the rights and obligations of individuals, Australians live in a world of courts and non-courts. This categorisation is dictated by Ch III of the Constitution. The exhaustive scheme of Ch III renders non-courts constitutionally incapable of exercising Commonwealth judicial power, and state judicial power in federal matters. No Australian Parliament can validly confer judicial power in federal matters on a non-court. This is not a mere technicality. The exercise of judicial power in federal matters is subject to two safeguards under Ch III: appeals to the High Court; and constitutional provisions for the institutional integrity of courts.

The constitutional divide between courts and non-courts necessarily calls attention to the qualities that are exclusive of executive power (i.e. that cannot be present in a conferral of executive power). The search for these qualities is especially important because so many decision-making authorities are ambivalent in the abstract, and can be performed through an exercise of judicial or non-judicial power at Parliaments' election. Take for example decisions to place individuals in non-punitive detention or subject individuals to preventative control orders; or decisions to alter rights or obligations upon a finding of non-compliance with statutory duties. Such decisions can be made by institutions exercising judicial power or executive power. For the constitutional separation of judicial power in federal matters to operate on such decisions - bringing important Ch III safeguards to bear - a clear understanding of the qualities denied to executive power is required.

One such quality is the capacity to affect legal rights and obligations through a purported decision (that is, a decision impaired by jurisdictional error). If made in exercise of judicial power, a purported decision can have a determinative effect on rights and obligations. If made in exercise of executive power, it cannot. The reasons for this are complex but of fundamental importance. I discuss this as a rationale for entrenched review elsewhere (see forthcoming in the Federal Law Review and Public Law Review). The gist of it is that executive power - quite unlike legislative and judicial power - is entirely subject to law. Prerogatives aside, there is no inherent (non-statutory) executive power over the legal rights or obligations of individuals.

Of course it is true that Australian Parliaments routinely vest powers to make decisions that have a governmental effect on rights or obligations in non-courts, including those that are constitutionally incapable of exercising judicial power. The point is that when Parliaments legislate in this way, it is the statute - operating on the fact of a valid decision - that affects rights and obligations. If the statute's operation is not engaged, non-statutory executive power cannot 'swap in' to support the decision as an exercise of public power over the individual.

With this in mind, we might hazard a summary statement of an important constitutional limit on legislative power. Fair warning - this won't be snappy. The limit is this: no Australian Parliament can enact a prospective rule that rights or obligations will be as specified in a purported decision by a non-court in a federal matter. Why? To enact such a rule would be an invalid attempt to confer judicial power on the non-court.

'Jurisdictional error' within the scheme of Ch III

The constitutional limit on legislative power I have described above relates to purported decisions, i.e decisions impaired by jurisdictional error. The concept of jurisdictional error undoubtedly has a long history in general law quite apart from the Ch III context. However, as our appreciation of the Ch III scheme - and associated limits on legislative power - evolves, we can see that its meaning in relation to jurisdictions exercised by non-courts must reflect the constitutional context. This requires express recognition that two dimensions of legislative power are denied by Ch III upon a finding of jurisdictional error. The first, as is well understood from cases like Plaintiff S157 and Kirk, is legislative power to oust or frustrate the entrenched measure of review. The second, less widely recognised but discernable in the authorities, is legislative power to affect rights and obligations on the fact of a non-court decision. As I have stated above (and discuss in more detail in the forthcoming publications noted above), this dimension of legislative power is denied, upon a finding of jurisdictional error, for any Commonwealth law operating through non-court decisions, and any state law operating through non-court decisions in federal matters.

When judges disagree on the elements of jurisdictional error, they are in effect disagreeing on how to calibrate the limits on legislative power implied from Ch III. Importantly, this is not just an exercise bearing on legislative power to oust or frustrate entrenched review. It also engages limits on legislative power to affect rights or obligations through non-court decisions. Evidently, there are counterpoised considerations in setting such limits on legislative power. On the one hand, the meaning that the Court gives to jurisdictional error must ensure that the limits on legislative power implied from Ch III go no further than 'logically or practically necessary' (Burns v Corbett per Gageler J at [94]) to preserve the integrity of the constitutional structure. On the other hand, the meaning must vindicate that underlying constitutional structure - one which denies judicial power in federal matters to non-courts.

The materiality precondition for 'jurisdictional error'

A materiality element makes sense if we view jurisdictional error as a marker for limits on legislative power to affect rights and obligations through non-court decisions. When jurisdictional error is viewed in these terms, a default materiality precondition is a principled means of calibrating the practical impact of jurisdictional error on legislative power. A materiality element ensures that the limits on legislative power derived from Ch III's exhaustive scheme (for courts to exercise judicial power in federal matters) go no further than logically or practically necessary to preserve that scheme. It is appropriate to adopt a default position that legislative power to operate on legal rights and obligations through non-court decisions should not be denied by errors that could not possibly have affected the decision.

At the same time, there is an obvious risk in taking an overly cautious or stringent approach to the materiality inquiry. It would be perverse to reason that because a dimension of legislative power is denied by the Constitution upon a finding of jurisdictional error, it is necessary to adopt a restrictive approach to jurisdictional error. Clearly enough, the doctrine that expresses constitutional limits shouldn't be used to undermine those limits. It is imperative to approach every element of jurisdictional error (including materiality) in a way that gives due effect to the constitutional scheme found in Ch III - one that denies judicial power in federal matters to non-courts.

It may be speculated that engaging with jurisdictional error in the context of judicial review can distract from its constitutional significance as a limit on legislative power. When it is encountered in judicial review proceedings, the concept presents as a doctrine well-known to the common law, and something that an applicant for review must prove to establish a remedy. However, this is not the whole picture. The central theme of this post is that the concept of jurisdictional error has a distinctive role within Ch III, as the marker for a constitutional limit on legislative power. The scheme laid down in Ch III of the Constitution is clear: in relation to federal matters, legal rights or obligations are not to be be affected by force of legislation operating on purported decisions of non-courts. This reflects a matter of fundamental constitutional importance: capacity to produce a binding legal effect on legal status despite jurisdictional error is a characteristic that is exclusive of executive power. These are fundamental constitutional considerations, not simply by-products of judicial review.

MZAPC (Part 2)

In the MZAPC reasons, some emphasis is given to the underlying constitutional limit on legislative power to affect rights and obligations through purported non-court decisions. It is tantalisingly close to the surface in the MZAPC majority reasons at [27] - [29] (just as it was tantalisingly close to the surface in Hossain at [23]). It is alluded to in the joint reasons of Gordon and Steward JJ at [96]. However the Court's reasons do not contain any overt or sustained focus on the specific role of jurisdictional error in marking limits on legislative power to operate through non-court decisions.

One might speculate that the MZAPC majority does have the constitutional limit on legislative power in mind. This is a plausible way of reconstructing Kiefel CJ, Gageler and Keane JJ's support for a materiality precondition in Hossain and SZMTA in the face of strong judicial criticism of its place as an element in jurisdictional error. If this assumption is sound, it invites a further speculation regarding the MZAPC majority's approach to jurisdictional error: it appears that their Honours are emphasising restraint in constitutional implications that limit legislative powers. Their Honours can't be faulted for this. However, it is difficult to shake the impression that something has gone awry in translation to the practice of review when the MZAPC majority insists on applicants' 'unwavering' onus to establish materiality (at [60]). While it is important that implied limits on legislative power have a firm basis in the Constitution's text and structure, it is also important that the entrenched measure of review is optimised to fulfil its constitutional purpose. In practical terms, this means that the materiality inquiry should enable review whenever there is any risk that legislation may be purporting to operate on the fact of a non-court decision in an unconstitutional way. The MZAPC minority's approach to proof of materiality would seem to strike a better balance in this regard.

Ultimately, the constitutional fundamentals that explain and require entrenched review of non-court decisions must be appropriately reflected in the Court's approach to jurisdictional error. It follows that a materiality precondition must operate to enable legal accountability for errors in decisions by non-courts constitutionally incapable of exercising judicial power. One would think that every facet of the inquiry into jurisdictional error must orient towards the underlying constitutional imperative: legislation cannot operate to affect rights or obligations on the fact of a purported decision by a non-court exercising executive power alone. If there is any risk of legislation so operating, the appropriate response for a court exercising entrenched review authority is to provide a remedy. The risk in these cases is not simply injustice for the individual whose legal status may be affected by legislation in error - although that is a risk that courts will not readily impose on individuals. The risk is also that legislation will operate in defiance of the institutional arrangements prescribed by the Constitution for judicial power in federal matters.

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Emily Hammond is an Associate Lecturer at The University of Sydney Law School.

Suggested citation: Emily Hammond, 'MZAPC: Calibrating constitutional limits on legislative power' on AUSPUBLAW (2 June 2021)