The single Supreme Court judgment dated 24th September 2019 in the "prorogation" appeals in the English case of R( on the application of Miller) (Appellant) v The Prime Minister (Respondent) and in the Scottish case of Cherry and others (Respondents) v Advocate General for Scotland ( Appellant) appears to have held as follows :-
- The question of the lawfulness of the Prime Minister's advice to the Crown to prorogue Parliament is a matter that is "justiciable" before the Courts;
- A decision to prorogue ( or advise the Crown to prorogue ) Parliament will be unlawful if the prorogation has the effect of frustrating or preventing , "without reasonable justification", the ability of Parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the Executive . In the present instance, the Prime Minister's advice to the Crown to prorogue Parliament was found to be unlawful within the meaning of this test;
- Being unlawful, the Prime Minister's advice to prorogue Parliament was "void and of no effect" and accordingly the act of prorogation itself was void and of no effect and , therefore, Parliament should be treated as not having been prorogued and as continuing in full force and effect;
- It is for Parliament to decide what to do next but the Court was not aware of any reason why each House of Parliament should not meet as soon as possible.
The above points are based on a review of the Supreme Court judgment itself, which has been posted on the Supreme Court website, and of the accompanying summary of the judgment ( which is, however, not part of the judgement itself) , which has also been posted on the Supreme Court website. The judgment ( and summary) will no doubt, however, be pored over by many commentators in the coming days and may be subject to many interpretations, which may differ from the above.
Whatever the nuances of interpretation, the Prime Minister has, nevertheless, quickly made it clear that the UK Government will comply with the terms of the Supreme Court judgment. We shall see in the coming days what exactly that means.
What is clear so far, however, is that the United Kingdom is a country governed by the Rule of Law operating within the context of a Parliamentary democracy and that, to quote the ancient Case of Proclamations  12 Co Rep 74, itself cited in the Supreme Court judgment, "the King hath no prerogative, but that which the law of the land allows him ".
Furthermore, the Supreme Court made it clear that, notwithstanding the English Bill of Rights 1688 and the equivalent Scottish Claim of Right 1689, the Courts are fully entitled to determine the legality of the purported prorogation of Parliament and that it does not fall outside the jurisdiction of the Courts as being a "proceeding in Parliament".
The Supreme Court judgment is a powerful unanimous decision of all 11 Supreme Court judges and will no doubt be essential reading for students of the British Constitution for many years to come.
As far as Brexit is concerned, the Supreme Court made it clear at the outset of its judgment that "the issue in these appeals is not when and on what terms the United Kingdom is to leave the European Union". The possible political fall-out from the Supreme Court decision should not, however, be under-estimated.