Illegality — ultra vires and errors of law

Illegality is the fundamental ground of judicial review, holding that public bodies act unlawfully when they exceed or abuse their statutory or common law powers. Following Anisminic Ltd v Foreign Compensation Commission [1969] 2 AC 147, virtually all errors of law are now reviewable as 'jurisdictional' errors, effectively collapsing the historical distinction between jurisdictional and non-jurisdictional errors. The rationale is constitutional: courts, not administrators, have final authority to determine questions of law, ensuring executive action remains within legal bounds. This principle operates through the ultra vires doctrine—that public bodies possess only those powers Parliament has granted—though modern scholarship debates whether review truly rests on legislative intent or derives from common law constitutional principles.

Anisminic Ltd v Foreign Compensation Commission [1969] 2 AC 147: A tribunal lacks jurisdiction if it addresses the wrong question, considers irrelevant matters, breaches natural justice, or reaches a decision unsupported by evidence. This expansive conception of jurisdictional error revolutionised judicial review by making virtually all legal errors reviewable despite ouster clauses.

R (Cart) v Upper Tribunal [2011] UKSC 28: The Upper Tribunal's refusal of permission to appeal is reviewable only where the case raises an important point of principle or practice, or there is some other compelling reason. This 'second appeals' threshold respects the tribunal architecture while preserving residual supervisory jurisdiction.

R (Privacy International) v Investigatory Powers Tribunal [2019] UKSC 22: Even clear ouster clauses cannot exclude review for jurisdictional error unless Parliament uses unmistakable language. The majority reaffirmed that judicial review for error of law is integral to the rule of law and constitutional settlement.

R v Lord President of the Privy Council, ex parte Page [1993] AC 682: Some anomalous categories (like university Visitors) retained immunity from review for non-jurisdictional error. Though Anisminic rendered the distinction obsolete in most contexts, it persists for superior courts of record and exceptional jurisdictions.

Courts begin by examining the statutory scheme to identify the decision-maker's powers and any limitations. The key question is whether the body has made an error of law—misinterpreting statute, asking the wrong question, or considering irrelevant factors. Post-Anisminic, such errors are treated as jurisdictional, rendering the decision ultra vires and void.

The analysis involves: (1) identifying the legal framework governing the decision; (2) determining what question the decision-maker was required to answer; (3) assessing whether they applied the correct legal test; (4) checking for procedural compliance. Ouster clauses require special attention—courts presume Parliament does not intend to exclude review unless using unmistakably clear language.

Intensity of review remains constant for pure legal questions (correctness standard), though context affects remedial discretion. The distinction between review and appeal remains crucial: courts examine legality, not merits.

Students frequently confuse illegality with irrationality—illegality concerns legal error (wrong statutory interpretation), while irrationality addresses unreasonable decisions. Many overstate Anisminic's effect, claiming it abolished all jurisdictional limits, when Cart and Page show the distinction persists for superior courts and special contexts.

Another trap is asserting ouster clauses never work—they fail against jurisdictional errors but sufficiently clear language can exclude review (post-2022 Cart restrictions prove this). Students often neglect statutory context, mechanically applying Anisminic without examining the specific legislative scheme. Finally, essays require engagement with the ultra vires versus common law debate—purely descriptive answers citing cases without analysing competing theoretical foundations will not achieve high marks.