15 May 2019
The Supreme Court has ruled in R (Privacy International) v Investigatory Powers Tribunal  UKSC 22 that the Investigatory Powers Tribunal’s decisions are nevertheless amenable to judicial review, despite the existence of a powerfully-drawn ‘ouster clause’ preventing its decisions from being questioned by a court.
In this article we will navigate our way through the decision and have a look at the principles that lie behind this case and what its wider significance might be.
The Investigatory Powers Tribunal (IPT) is the body which has jurisdiction to examine the conduct of the Security Service, the Secret Intelligence Service and the Government Communications Headquarters (GCHQ). Effectively, the IPT is the court where a person can challenge the lawfulness of a decision to put them under surveillance.
The question in this case was whether the decisions of the IPT itself could be challenged in court. In particular, did the High Court have jurisdiction to entertain an application for judicial review brought by Privacy International against a decision by the IPT that computer hacking by GCHQ fell lawfully within its general warrant to undertake such activity?
The ouster clause
This case involved the interpretation of what is known as an ‘ouster clause’ — called this because its aim is to ‘oust’ the jurisdiction of the courts to question a decision by a statutory body.
The ears of public law students will surely have pricked up at these words, for of course they bring to mind the case of Anisminic Ltd v Foreign Compensation Commission  UKHL 6, one of the most famous cases in the development of modern British public law.
In that case, a statutory commission was given the job of deciding whether compensation should be awarded for property sequestrated as a result of the 1956 Suez Crisis. The legislation empowering it involved an ouster clause which provided that the
determination by the Commission of any application made to them under this Act shall not be called in question in any court of law.
However, the House of Lords ruled by a 3-2 majority that this provision was not enough to oust judicial review for an error of law.
The majority considered that the commission had based its decision on an inquiry into the nature of the appellant company which the legislation did not empower it to make. Therefore, it had gone outside its jurisdiction. This meant that the determination that the appellant did not qualify to be paid compensation was not a true determination, but a nullity. As the ‘determination’ was not a determination at all, there was no problem with the court calling it into question.
This reasoning may seem redolent of Alice in Wonderland. But the seriousness of the issue behind the word game cannot be doubted. The jurisdiction of the High Court to supervise decisions by the commission was considered by the majority of the House of Lords to be so important that the language of the ouster clause was not enough to displace it. And so the ouster was ousted.
The Court of Appeal’s decision
However, in Privacy International’s case, the Court of Appeal had decided that the ouster preventing the IPT’s decisions from being challenged did successfully oust the jurisdiction of the High Court.
The ouster is set out in section 67 (8) of the Regulation of Investigatory Powers Act 2000, which provides that
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.
The view of the Court of Appeal, as discussed by David Hart QC here, was that this was materially different from that in Anisiminic, as it expressly ousted jurisdiction to question whether the IPT had jurisdiction. As such,
… the drafter of section 67(8) has expressly adverted to the possibility of the IPT making an error of law going to its jurisdiction or power to act, by the words in parenthesis in that provision: “including decisions as to whether they have jurisdiction”. Therefore, at least so far as the word “decision” is concerned, it is not tenable to apply the simple distinction relied upon in Anisminic in the context of section 4(4) of the 1950 Act between a “determination” and a purported determination, in the sense of a determination made without jurisdiction.
The conclusion was that the legislation had been drafted in such a way at to enable the IPT, the expert body tasked with examining decisions on the use of investigatory powers, to make decisions on issues before it including on questions of law without the need for the High Court to have ultimate supervision.
The Supreme Court’s decision
The case came before a 7-judge panel of the Supreme Court. By a 4-3 majority (as narrow as the scoreline in the Anisminic decision), the court allowed the appeal.
First, Lord Carnwath disavowed the logical gambit used in Anisminic, stating that
it is highly artificial, and somewhat insulting, to describe the closely reasoned judgment of this eminent tribunal as a “nullity”, merely because there is disagreement with one aspect of its legal assessment. 
He considered that the case law — not least the decision of the Supreme Court in 2011 that an unappealable decision of the Upper Tribunal was still subject to judicial review — had moved things on from these “somewhat technical debates”. But it nonetheless demonstrated
the continuing strength of the fundamental presumption against ousting the supervisory role of the High Court over other adjudicative bodies, even those established by Parliament with apparently equivalent status and powers to those of the High Court. 
He then noted that this presumption is based on what is known as the ‘principle of legality’: when enacting legislation
Parliament must squarely confront what it is doing and accept the political cost. 
The practical importance of this principle was seen when clause 11 of the Asylum and Immigration (Treatment of Claimants etc) Bill 2003 was introduced. That clause introduced an extreme ouster which expressly precluded a court from entertaining proceedings to determine whether a purported decision was a nullity for any reason. The clause was withdrawn after it met powerful objections within and outside Parliament .
Turning to the ouster clause in this case, Lord Carnwath considered that it was not as clear as it might have been:
A more explicit formula might perhaps have anticipated the extreme wording of the bill presented in 2003 (para 101 above), excluding challenges to any determination or “purported” determination as “a nullity by reason of lack of jurisdiction, error of law, or any other matter”. The reason for not adopting that course may simply be that, as in 2003, it might not have been expected to survive Parliamentary scrutiny. 
He concluded that the ouster clause was not clear and explicit enough to oust the jurisdiction of the High Court to consider a challenge to a decision by the IPT.
This is a highly significant decision which may have wide ramifications. In the concluding section of the leading judgment, Lord Carnwath said that although he had not had to decide on the general lawfulness of ouster clauses,
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. 
The full significance of this statement, which was not part of the binding ratio and on which Lord Lloyd-Jones, another of the Judges in the majority, remained neutral , may be discovered if the day comes that Parliament passes an ouster clause extreme enough to embrace such an eventuality. But that was not today.
Jonathan Metzer is the commissioning editor of the UK Human Rights Blog. He is a barrister at One Crown Office Row.