Thomas Fairclough: Judicial Review and Article 50: Some Preliminary Issues

Tom FaircloughIntroduction

There has been much debate on Article 50 TEU. More specifically, there have been thoughtful arguments about who or what has legal authority to trigger Article 50 and begin the Brexit process. Some have said it’s the Government acting under the Royal Prerogative whilst others have said it is for Parliament to start. My own view is that it is to be done pursuant to the Royal Prerogative, and therefore the Government has legal jurisdiction to begin the Article 50 process. However, the point is clear arguable either way.

This debate has led to calls for a judicial review of a decision to invoke Article 50 by the Prime Minister (if and when such a decision is made) and anonymous parties are now backing such a challenge. This piece addresses issues regarding such a judicial challenge to a decision by the Executive to start the Brexit process. More specifically, it examines the concerns surrounding the justiciability of any such decision.


In the comments on Barber, Hickman, and King’s well argued piece concerns were raised that, even if they are correct and it is for Parliament, not the Executive under the Royal Prerogative, to trigger Article 50 the issue would be non-justiciable and the High Court would likely refuse to hear such a challenge to the Prime Minister’s decision. Therefore, failing a challenge in the CJEU (the prospects of which I make no comment on here) the decision would stand.

Traditionally, separation of powers led the courts to generally decline to interfere with matters of policy. Hence, in R (oao Hooper) v SSWP [2003] EWCA Civ 813; [2003] 1 WLR 2623 at [63]-[64] Lord Justice Laws stated that “a very considerable margin of discretion must be accorded….[where] questions of economic and social policy [are] involved”. More specifically, Lord Bingham noted in R (oao Gentle) v Prime Minister [2008] UKHL 20; [2008] 1 AC 1356 at [8] there is “restraint traditionally shown by the courts in ruling on what has been called high policy- peace and war, the making of treaties, the conduct of foreign affairs”.

The argument for the Government, in relation to the rejiggering of Article 50, would undoubtedly be that this is a quintessential area where the courts should be slow to tread. It is completely and clearly axiomatic to say that the decision to begin the process of leaving the European Union is one of the most polycentric (socially, politically and economically) decisions a Government can make. Once that decision was made it any interference by the High Court be fraught with difficulties and therefore improper. The Government lawyers would, I am sure, make these arguments at permission stage to try to avert a full hearing on the issue.

Justiciability and Jurisdiction

The argument that the Government would undoubtedly make in the event of a judicial review is, at first blush, relatively strong. It does seem, at least initially, that an Executive decision to leave the European Union is one of the utmost “high policy” and, therefore, it would be wrong for the High Court to intervene. I think, however, that this argument, whilst initially convincing, is perhaps too simplistic to survive rigorous testing (and therefore survive a sufficiently robust Justice in the High Court).

The claimant in such a judicial review would possibly be able to make the following argument to alleviate (at least temporarily) any justiciability point. The concerns relating to justiciability, which mainly revolve around the constitutional status and institutional capability of the High Court, do not apply in a case where you are simply seeking to determine the legal basis of an Executive act. Generally, arguments around justiciability focus on the impropriety of substituting the Government’s view with the court’s on a substantive review (that is, the normal Wednesbury standard is weakened to such an extent that it barely applies anymore).

However, in such a judicial review the claimants would, hopefully, not be challenging the decision (at least initially) on its merits or process. Instead, they would focus on jurisdiction in the first place. It is clear from Attorney General v De Keyser’s Royal Hotel Ltd. [1920] AC 508 that the courts have the ability to determine whether a Royal Prerogative power exists and, if it does, its scope and the extent to which it has been superseded by statute (as both Tucker and Barber, Hickman, and King argue it has been for present purposes.). Likewise, in the GCHQ case Lord Fraser stated “the courts will inquire into whether a particular prerogative power exists or not and, if it does exist, into its extent.”.

This would, presumably, be the first line of argument in any prospective judicial review: the initial question for the court would not be whether the Prime Minister used his or her power substantively correctly, or followed a lawful process, but rather whether he or she had power to act at all. The applicants would not be asking the court to rule on the decision or its process (where justiciability bites) but rather on the legal basis of that (purported) decision, which is inherently within the court’s role in our constitution. If, as others have argued, the European Communities Act 1972 displaces the Royal Prerogative power in relation to the EU and Article 50 then the High Court could potentially rule on this without any justiciability issues.

Justiciability after Jurisdiction

But what if the court decided, in line with Elliott’s and my own view, that the ECA did not supersede the Royal Prerogative in this area? This is, I suspect, where justiciability concerns would bite. Whilst in GCHQ the majority of the House of Lords said it was no longer appropriate to refuse to hear a case because the legal basis of a decision was the prerogative, they were still of the opinion that the subject matter of any decision may render it non-justiciable. Lord Roskill, somewhat tentatively, listed examples of areas where the courts would not lightly tread such as “such as those relating to the making of treaties, the defence of the realm, the prerogative of mercy, the grant of honours, the dissolution of Parliament and the appointment of Ministers”.

Whilst the courts have somewhat loosened this staunch and binary approach they will still question “whether the nature and subject matter of the decision is amenable to the judicial process” (see Watkins LJ in R v. SSHD Ex p. Bentley [1994] QB 394, 453). It is still the case, I argue, that acts at “the top of the scale of executive functions under the prerogative” involving “high policy” (see R v Secretary of State for Foreign and Commonwealth Affairs Ex p. Everett [1989] QB 811) are generally not susceptible to judicial review unless something has gone catastrophically wrong in the decision making process (Watkins LJ makes a not dissimilar point in Bentley at p 453). Short of any Prime Minister, in starting the Article 50 process, acting completely irrationally (within the furthest reaches of Wednesbury) I find it difficult to envisage a court quashing his or her decision.


The debate as to whether the Prime Minister or the legislature has legal authority to decide when to start the Article 50 process remains unresolved. This piece does not take sides on that though, as stated above, my own view is that, pursuant to the Royal Prerogative, it is for the Prime Minister to decide under the current settlement. The aim of this piece is simply to look at the prospects of a judicial review of a decision by the Prime Minister to trigger Article 50. Despite some commentators’ reservations, I believe justiciability, at least at the initial stage, would not prove a barrier to such a judicial review. All the applicants in such a case would be doing is asking the court to determine whether the Prime Minister has such a power, not whether he or she exercised it fairly or was substantively correct. If the High Court decides for the prospective applicants, and says that the Prime Minister did not have the power to act, then, legally, the case is over (I leave aside whether the High Court, pursuant to its powers of discretionary relief, would quash an Article 50 notification after it has been received by the European Council).

However, if the High Court decides that the ECA does not preclude the Prime Minister, under the Royal Prerogative, from starting the Article 50 process then justiciability concerns would come to the fore. It is, in my opinion, nearly impossible to envisage a situation in which the High Court decides that the Prime Minister had the power to trigger Article 50 but holds, on either procedural or substantive grounds, he or she acted illegally in doing so.

Thomas Fairclough, AHRC PhD Candidate at Gonville and Caius College, Cambridge and Teaching Fellow in Public Law and Jurisprudence at University College London. I would like to Mark Elliott for his comments on this piece. Any mistakes are my own.

(Suggested citation: T. Fairclough, ‘Judicial Review and Article 50: Some Preliminary Issues’, U.K. Const. L. Blog (6th Jul 2016) (available at