The High Court (Divisional Court of the Queen's Bench Division) - Lord Burnett CJ, Sir Terence Etherton MR and Dame Victoria Sharp (President QBD) held that the decision of the Prime Minister to advise Her Majesty the Queen to prorogue Parliament is not justiciable in Her Majesty’s courts- - Judiciary - Gina Miller v Prime Minister and others  EWHC 2381 (QB).
In Scotland's Court of Session (Outer House) - Lord Doherty - reached
a similar conclusion - Cherry  CSOH 70.
The Court of Session (Inner House) - - Lords Carloway, Brodie and Drummond Young - has unanimously reversed that decision holding that the advice given to HM The Queen to prorogue parliament was unlawful and that the prorogation was therefore unlawful - The Scotsman 11 September 2019. The full judgments of the Inner House are to be handed down on Friday 13 September.
The Inner House judgment is Joanna Cherry QC MP v Advocate General  CSIH 49
See also Scottish Council of Law reporting - Cherry v Lord Advocate
Judgment of McCloskey LJ - McCord, JR83 and Jamie Waring v Prime Minister and others  NIQB 78
Note para 116 - "I consider the characterisation of the subject matter of these proceedings as inherently and unmistakeably political to be beyond plausible dispute. Virtually all of the assembled evidence belongs to the world of politics, both national and supra-national. Within the world of politics the well recognised phenomena of claim and counterclaim, assertion and counter-assertion, allegation and denial, blow and counter-blow, alteration and modification of government policy, public statements, unpublished deliberations, posturing, strategy and tactics are the very essence of what is both countenanced and permitted in a democratic society. The briefest of reflections on this incomplete and rudimentary formulation serves to reinforce the twofold juridical truisms that the judicial function must respect certain boundaries and, in instances where there is no “boundary” prohibition, a concrete and completed act of government having legal effects and consequences is an essential pre-requisite to the invocation of the supervisory jurisdiction of the High Court."
Supreme Court of the UK:
The Supreme Court of the UK will be convened on 17 September to hear appeals from these judgments. The court's composition of 11 is to be Lady Hale (President), Lord Reed (Deputy President), Lord Kerr, Lord Wilson, Lord Carnwath, Lord Hodge, Lady Black, Lord Lloyd-Jones, Lady Arden, Lord Kitchin and Lord Sales. [The Justice not sitting is therefore Lord Briggs]. See the Court's Announcement.* The court currently has a full complement of 12 but has to sit with an uneven number of justices - Constitutional Reform Act 2005 s.42.
Public Law for Everyone 12 September - Prorogation and justiciability: Some thoughts ahead of Cherry/Miller (No 2) case in the Supreme Court
Brexit Institute 12 September - Prorogation and the case for constitutional reform
Scottish Legal News 11 Septemer - Inner House's remarkable judgment on prorogation could have long lasting constitutional implications