Last week in Cherry v Lord Advocate the First Division, Inner House, Court of Session  CSIH 49 P680/19 held that Mr Johnson’s decision to advise the Queen to prorogue Parliament for five weeks was justiciable. The key part of the decision is quoted below.
“ I can see that just because a government has resorted to a procedural manoeuvre in order to achieve its purpose does not mean that there is necessarily scope for judicial review. Procedural manoeuvres are the stuff of politics, whether conducted in Parliament or in lesser bodies. However, when the manoeuvre is quite so blatantly designed “to frustrate Parliament” at such a critical juncture in the history of the United Kingdom I consider that the court may legitimately find it to be unlawful.
There are undoubted difficulties in the courts applying its supervisory jurisdiction to an exercise of the royal prerogative within the political sphere, but Mr Johnston for the respondent did not go the distance of saying that there could never be a case which would justify intervention. He accepted that a two year prorogation of Parliament might be amenable to review. Here, the prorogation is only five weeks (and it is to be borne in mind that in practice the reduction of sitting days will be less because of the traditional adjournment of Parliament during the political party conference 49 season). However, it is a lengthy prorogation at a particularly sensitive moment when time would seem to be of the essence. In my opinion Mr Mure QC for the Lord Advocate (whose analysis I accept) was right to point to the dictum of Lord Sumption in Pham v Secretary of State  UKSC 19 at paras 105-106: “in reality [there is] a sliding scale, in which the cogency of the justification required for interfering with a right will be proportionate to its perceived importance and the extent of the interference”.
Here there has been interference with Parliament’s right to sit, should it wish to. The petitioners want to protect that right. If Parliament does not wish to be so protected it can decide accordingly but the petitioners want to give it the opportunity to determine whether and when it is to sit between now and 31 October. The petitioners submit that as yet Parliament has not had that opportunity, notwithstanding the legislative activity that was going on during the hearing of the reclaiming motion.
What has led me to conclude that the court is entitled to find the making of the Order unlawful is the extreme nature of the case. A formulation to which I have been attracted is found in chapter 14, Crown Powers, the Royal Prerogative and Fundamental Rights, in Wilberg & Elliott, The Scope and Intensity of Substantive Review (Hart, 2015) at p 374 where the author of the chapter, Sales LJ, as he then was, refers to a group of authorities where the courts had been prepared to review exercises of the Crown’s common law and prerogative powers. The formulation is: “these are egregious cases where there is a clear failure to comply with generally accepted standards of behaviour of public authorities”. I see this as an egregious case. Mr O’Neill came to submit that the essence of the illegality here was irrationality (as had been the cases with the cases referred to by Sales LJ). Mr O’Neill may be right about that, although I would see it as having to do with improper purpose. At all events, I consider the Order to be unlawful and that making it was contrary to the rule of law.”
A contrario, the English High Court has found that the matter is one of high politics and is not justiciable.
The case is currently being heard on appeal in the Supreme Court. Eleven of the Twelve Justices of the Supreme Court are hearing the case.