A great deal of the comment on this case, which is summarised in Jonathan Haydn Williams' note, has not taken into account that it is a typical judicial review, in which the claimants maintain that certain "rights" are to be removed by government to their detriment. What has also not been commented on extensively, is the fact that litigation can be shaped by the concessions that parties make and this one is no exception. However, concessions (if they are ones of law) can be withdrawn right up to judgment – provided always that costs are paid by the party withdrawing the concession.

With this prosaic but essential background in mind, it is noteworthy that before the High Court, the government conceded that the referendum was purely advisory (sharing the views of the claimants) but nevertheless sought to justify giving some kind of binding force to the popular will by the proposed exercise of prerogative powers to start the process of leaving the EU by itself sending the Article 50 Notice which triggers exit without parliamentary involvement. Such exercise of prerogative powers would, arguably, affect the rights of the various claimants in this case. At the same time, the government, again in agreement with the claimants, accepted that the mere invocation of Article 50 was irrevocable even though it aims to dilute as little as possible the rights of the class of people of whom the claimants form part. If the government were to fail to protect the claimants, (or any of them) one would have thought that it might want to withdraw the Article 50 notice. So it is not clear why the government was prepared to go along with the claimant's argument that the Article 50 notice was irrevocable.

The unjaundiced observer might say on the basis of these concessions that the government does not want to win its case. Certainly, its position looks incoherent and reading the transcripts of the hearing before the High Court, it is quite understandable why its counsel was given such a hard time.

Domestic law helps to identify the really important question in this litigation – once again procedure is the key. The leading textbook (Fordham, sixth edition at 4.7.1) says that some judicial review applications may be characterised as being made "too soon". Thus "the court may regard it inappropriate to rule on a grievance which is not yet ripe for review and which may turn out not to have practical significance". The textbook then quotes a large number of cases where the courts have refused to act in anticipation of decisions that have yet to be taken. This is by no means an absolute rule: subsequent paragraphs in Fordham discuss cases where the Courts indeed have taken the bull by the horns early on before decisions have been taken. Strangely, in the High Court, the government argued for judicial non-intervention because any apprehended loss of rights was unclear and yet appeared prepared to concede that Article 50 was irrevocable. This can hardly have helped its case. However, it is quite clear that is not bound by such a concession and would be free to withdraw it before the Supreme Court and apparently this is an option that it is considering.

On the critical point of revocability of an Article 50 notice, views are divided – but not equally. The Vienna Convention on the Law of Treaties provides that a notification of intention to withdraw from a Treaty may be revoked at any time before it takes effect. Article 50 itself says that once invoked, EU Treaties cease to apply two year after notification but, crucially, this happens only in the absence of a withdrawal agreement (increasingly likely it would appear) which would extend the negotiating period.  Moreover, Article 50 itself could be amended if all the Member States agree.

The Commission President Donald Tusk, reflecting the view of its Legal Service has said that revocation of an Article 50 notice is entirely possible from a legal point of view. Such a view has also been expressed by Lord Kerr who drafted the exit clause, former Judges of the EU Court of Justice and Paul Craig, Professor of English Law at Oxford University. Though others have expressed a different view, that view ignores the political reality that all Member States have an equal interest in getting out of Article 50's two year straightjacket.

If the legal position and political reality is that an Article 50 notice can indeed be withdrawn, the effect on the claimants' rights in this case as a result of notice being served is remote and the challenge arguably premature since no reviewable "decision" has yet arisen or would do so for the foreseeable future. This argument looks strong in this litigation. Indeed, the Article 50 process is unlikely to be anything like the firing of the bullet from the gun – which is how Lord Pannick characterised it. The characterisation of anything at all in European matters as having this degree of finality ignores not just the far from unqualified wording of Article 50 but also the fact that the European "train" is still mostly on its "platform" despite economic and monetary union having repeatedly promised since the European Community was run by Giscard D'Estaing and Helmut Schmidt in the 1980's.

If this were a normal litigation, one would therefore expect the government to withdraw the concession and the Supreme Court would then merely have to decide whether mere invocation is a reviewable "decision" now or whether the challenges are premature and should be left to some future date when the impact on the claimants' rights looks like being crystallised. Nevertheless, if it withdraws the concession and defeats this challenge on the grounds of its prematurity (which looks strong once it is accepted that the Article 50 notice is revocable), the problem will not go away for the question who has the power to revoke the Article 50 notice – the Executive or Parliament – might still need to be resolved at some future date. As matters currently stand, the government's position in this litigation is uncomfortable to say the least and it is not surprising that some have argued it should drop its appeal before the Supreme Court.

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