On 15 May 2019, the UK Supreme Court ruled 4-3, in R (on the application of Privacy International) v Investigatory Powers Tribunal and others  UKSC 22, that rulings of the Investigatory Powers Tribunal are subject to the supervisory jurisdiction of the High Court on the point of law. In its ruling, the Supreme Court discusses a common law presumption against clauses restricting access to judicial review and, more crucially, the limits of the doctrine of parliamentary sovereignty.
The Investigatory Powers Tribunal is a specialist tribunal created by the Regulation of Investigatory Powers Act 2000 (RIPA 2000) and tasked with supervising intelligence surveillance and other conduct of the Security Service, the Secret Intelligence Service and the Government Communications Headquarters (GCHQ). Under RIPA 2000, s 67(8), rulings of the Investigatory Powers Tribunal seem to be final:
“Except to such extent as the Secretary of State may by order otherwise provide, determinations, awards and other decisions of the Tribunal (including decisions as to whether they have jurisdiction) shall not be subject to appeal or be liable to be questioned in any court.”
However, Lord Carnwath, in his Majority Opinion, held that judgments containing errors of law were not ‘determinations’ within the meaning of RIPA 2000, s 67(8) and the supervisory jurisdiction was therefore not ousted. This interpretation flows from the old decisions of the House of Lords in Anisminic v Foreign Compensation Commission  2 AC 14 and O’Reilly v Mackman  UKHL 1 which established that:
“…If a tribunal whose jurisdiction was limited by statute or subordinate legislation mistook the law applicable to the facts as it had found them, it must have asked itself the wrong question, ie, one into which it was not empowered to inquire and so had no jurisdiction to determine. Its purported ‘determination’, not being a ‘determination’ within the meaning of the empowering legislation, was accordingly a nullity…” [para 54]
Therefore, Lord Carnwath held that ‘…a determination arrived at on an erroneous view of the relevant law was not a “determination” within the meaning of an ouster clause...’ [para 54]. This approach is consistent with a general common law presumption against ousting the jurisdiction of the High Court [para 107].
However, in his Majority Opinion, Lord Carnwath moves beyond the common law presumption against clauses restricting access to judicial review and the concept of ‘nullity’ determinations and suggests that the question of the supervisory jurisdiction of the High Court should come down to the concept of the rule of law:
“This proposition should be seen as based, not on such elusive concepts as jurisdiction (wide or narrow), ultra vires, or nullity, but rather as a natural application of the constitutional principle of the rule of law (as affirmed by section 1 of the [Constitutional Reform Act] 2005), and as an essential counterpart to the power of Parliament to make law. The constitutional roles both of Parliament, as the maker of the law, and of the High Court, and ultimately of the appellate courts, as the guardians and interpreters of that law, are thus respected…” [para 132]
“…Arguably, following the logic of the reasoning in R (Cart) [v Upper Tribunal  UKSC 28], it may be thought implicit in the constitutional framework for the rule of law, as established by the Senior Courts Act 1981 and the Constitutional Reform Act 2005, that legal issues of general importance should be reviewable by the appellate courts; and that an ouster clause which purports to exclude that possibility cannot, consistently with the rule of law, be upheld…” [para 142]
Consequently, Lord Carnwath concluded that:
“…[A]lthough it is not necessary to decide the point, I see a strong case for holding that, consistently with the rule of law, binding effect cannot be given to a clause which purports wholly to exclude the supervisory jurisdiction of the High Court to review a decision of an inferior court or tribunal, whether for excess or abuse of jurisdiction, or error of law. In all cases, regardless of the words used, it should remain ultimately a matter for the court to determine the extent to which such a clause should be upheld, having regard to its purpose and statutory context, and the nature and importance of the legal issue in question; and to determine the level of scrutiny required by the rule of law.” [para 144]
The Majority Opinion in R (on the application of Privacy International) v Investigatory Powers Tribunal and others  UKSC 22 constitutes a vital part of UK constitutional jurisprudence on the doctrine of parliamentary sovereignty as it seems to suggest that there are some ultimate limits as to what Parliament can and cannot do. The Supreme Court appears to suggest that the concept of the rule of law might pose limits to the Parliament’s power to regulate access to judicial review. It is not clear what those limits are but the Court points to the fact that unlike the Court of Appeal and the Supreme Court, which are the creation of statutes, the High Court enjoys the original common law jurisdiction [para 141] and, although there is no constitutional right of appeal form the High Court, its supervisory jurisdiction is somehow special because ‘[a]t least since the time of Blackstone, this has been a central part of the function of the High Court as constitutional guardian of the rule of law’ [para 139]. The Supreme Court therefore recognises the long history of the supervisory jurisdiction of the High Court which was established at the end of the 13th century as the King’s Bench and its ‘supervisory role was preserved by section 16 of the Judicature Act 1873 which vested the common law powers of the Queen’s Bench in the newly created High Court. Those powers were in turn preserved by section 19 of the Senior Courts Act 1981‘ [para 33].
Although the Supreme Court points to the Judicature Act 1873, the Senior Courts Act 1981 and the Constitutional Reform Act 2005 as a potential source of the rule of law, those statutes only recognised the powers of the High Court and the concept of the rule of law, rather than created them. The Judicature Act 1873 combined the Court of Chancery, the Court of Queen’s / King’s Bench, the Court of Common Pleas, the Court of Exchequer, the High Court of Admiralty, the Court of Probate and the Court of Divorce and Matrimonial Causes into the Supreme Court of Judicature, composed of the High Court with original jurisdiction and the Court of Appeal with appellate jurisdiction. The Senior Courts Act 1981, s 19 provided that ‘(2) [s]ubject to the provisions of this Act, there shall be exercisable by the High Court – (b) all such other jurisdiction (whether civil or criminal) as was exercisable by it immediately before the commencement of this Act…’ while the Constitutional Reform Act 2005, s 1 provided that ‘[t]his Act does not adversely affect – (a) the existing constitutional principle of the rule of law…” None of these Acts created supervisory jurisdiction of the High Court, nor did they established the rule of law as one of the principles of UK constitutional law but rather recognised what had already existed.
Finally, the Supreme Court confirmes that as ‘constitutional statutes’, the Judicature Act 1873, the Senior Courts Act 1981 and the Constitutional Reform Act 2005 are immune to implied repeal by Parliament [para 120]. Consequently, Parliament cannot implicitly modify rules governing the supervisory jurisdiction of the High Court. The question remains, what would happen if Parliament was to expressly abolish that jurisdiction or the concept of the rule of law in its entirety. It is not clear from the judgment whether Parliament can abolish something that it has not created but only recognised as already in existence.