Judicial review of administrative action 

Judicial review is the process by which courts supervise the legality of administrative decisions. It is deliberately narrower than merits review: a court does not ask whether a decision was correct or preferable, only whether the decision-maker acted within the limits of the power the law gave them.

Legality, not merits

The central discipline of judicial review is that a reviewing court must not trespass into the merits. If a decision-maker had a discretion to exercise, and exercised it within power, a court cannot overturn the outcome merely because the judge would have decided differently. This restraint reflects the separation of powers: judicial review supervises the boundaries of executive power without the courts themselves taking over the executive function of deciding what the substantively best outcome should be. The distinction between legality and merits is not always easy to draw in practice, and much of the skill in judicial review problem-solving lies in showing that a complaint is genuinely about the legal limits of power, not a disguised complaint about the outcome.

The general grounds of review

At a conceptual level, the grounds on which a court may find an administrative decision unlawful cluster into three broad categories.

• Illegality (or ultra vires). The decision-maker did something the law did not authorise — acting beyond the power conferred by the enabling statute, misconstruing the scope of that power, applying the wrong legal test, or failing to exercise a discretion that was required to be genuinely exercised. "Ultra vires" captures the underlying idea: the decision-maker went beyond ("ultra") the powers ("vires") given to them.
• Procedural unfairness. The decision-maker failed to follow a fair process, whether by denying a person a genuine opportunity to be heard or by deciding the matter with actual or apprehended bias.
• Unreasonableness. The decision, though within the decision-maker's formal power, was so unreasonable that no reasonable decision-maker could have made it. This ground is deliberately narrow, precisely because a broader unreasonableness standard would collapse the distinction between legality and merits. Australian Broadcasting Tribunal v Bond (1990) 170 CLR 321¹ (Mason CJ) is the leading authority for keeping this ground narrow, and for the related point that not every step in a decision-making process is itself a reviewable "decision".

These categories overlap in practice, and a single set of facts often supports more than one characterisation. They are best understood as different ways of showing that a decision-maker exceeded the legal limits of the power Parliament actually conferred, rather than as a rigid checklist applied mechanically.

No single national scheme

Judicial review is not delivered through one uniform Australian statute. The Commonwealth has its own judicial review legislation — the Administrative Decisions (Judicial Review) Act 1977 (Cth), which states the grounds as a statutory list³ — and its own arrangements for supervising Commonwealth decision-makers, while each state and territory has its own judicial review statute, procedural rules, and inherent or statutory supervisory jurisdiction exercised by its Supreme Court. The underlying legal concepts are shared, but the precise cause of action, available remedies, and procedural preconditions differ between jurisdictions, and a student must always check which jurisdiction's regime governs the decision in question.

Section 75(v) and constitutional entrenchment

Judicial review of Commonwealth officers has a distinctive constitutional foundation. Section 75(v) of the Constitution gives the High Court original jurisdiction in matters in which a writ of mandamus, prohibition, or an injunction is sought against an officer of the Commonwealth.² Because this jurisdiction is conferred directly by the Constitution, Parliament cannot remove it by ordinary legislation — including by a privative clause that purports to declare a decision immune from judicial review. This entrenchment means there is an irreducible constitutional minimum of judicial review available against Commonwealth decision-makers, no matter how a statute attempts to insulate their decisions from challenge. The content of that constitutional minimum is closely tied to the concept of jurisdictional error, treated separately, since it is jurisdictional error that a privative clause cannot validly exclude.

Entrenchment does not make the jurisdiction a concurrent route to review. In San Bao Pty Ltd v Minister for Immigration and Citizenship [2026] HCA 6⁶, Edelman, Steward and Gleeson JJ said that the Court's original jurisdiction "does not exist as a concurrent review mechanism" for a plaintiff who has not applied for review within the strict time limits the legislation sets. Other than in exceptional cases, where importance, merits or urgency requires otherwise, review should proceed through the hierarchy of tribunals and courts, and "it will often be an abuse of process to seek to circumvent that hierarchy"; the mere unavailability of the usual route is not by itself an exceptional reason. Gordon, Steward and Beech-Jones JJ applied that reasoning in Plaintiff S32/2026 v Minister for Immigration and Citizenship [2026] HCA 27⁷, holding an application for constitutional writs against a protection visa refusal to be an abuse of process on the circumstances of that case: the plaintiff had not participated in the Administrative Review Tribunal's merits review and the Tribunal had rejected his explanations, he had not challenged either Tribunal decision for jurisdictional error, and he could still seek judicial review of the Tribunal's confirmation decision in the Federal Circuit and Family Court, success in which would return him to merits review. The Court added that, in any event, the visa decision was not affected by jurisdictional error. Both cases arose under the Migration Act 1958 (Cth) review scheme.

Remedies

Judicial review remedies are traditionally described using the language of the prerogative writs and their modern equivalents: an order quashing an invalid decision (certiorari), an order compelling a decision-maker to perform a duty (mandamus), an order restraining an unlawful exercise of power (prohibition), together with declarations and injunctions. Each remedy is discretionary, and a court may decline relief even where a ground of review is established, for reasons such as delay or the absence of any practical utility in granting it.

Applying this in a problem question

1. Identify the decision-maker, the source of their power, and whether they are a Commonwealth, state or territory officer, since this affects which judicial review regime applies.
2. Characterise the complaint as illegality, procedural unfairness, or unreasonableness (or more than one), and test whether it is genuinely about legality rather than the merits. On unreasonableness, do not confine the ground to the irrational or bizarre: in Minister for Immigration and Citizenship v Li [2013] HCA 18⁴ Hayne, Kiefel and Bell JJ said at [76] that "[u]nreasonableness is a conclusion which may be applied to a decision which lacks an evident and intelligible justification". In Minister for Immigration and Border Protection v SZVFW [2018] HCA 30⁵ Kiefel CJ, applying that formulation, described the test as necessarily stringent, and Nettle and Gordon JJ said it would be a rare case to find a discretion unreasonable where the reasons demonstrated a justification.
3. If the decision-maker is a Commonwealth officer, consider whether s 75(v) is engaged and whether any privative clause could validly exclude the ground relied upon, and whether a statutory review route is or was available, since seeking relief in the High Court instead may be an abuse of process.
4. Identify the remedy sought and consider discretionary reasons a court might decline to grant it.
5. Keep merits review and judicial review analytically separate throughout, even where both might be factually available.