A Scottish court has today declined to intervene in the challenge to prorogation brought in the court of session as follows.
 In my opinion the authorities discussed during the submissions vouch the following propositions. The exercise of some prerogative powers in some circumstances is justiciable, in other cases it is not. The court’s role in relation to prerogative powers is dependent on the nature and the subject matter of the power or its exercise, particularly on whether the subject matter is justiciable. Whether the exercise of a prerogative power is reviewable depends on the subject-matter and the context of the power and of the challenge. Some functions
exercised or decisions taken are non-justiciable. Among them are matters of high policy and political judgement. The court does not have the tools or standards to assess the legality of such matters. That is political territory and decision-making which cannot be measured against legal standards, but rather only by political judgments. The courts will not seek to superimpose legal controls on such matters. Rather, the accountability for them is to Parliament and the electorate.
 I am not persuaded that any of the matters relied upon by the petitioners or the Lord Advocate result in the claim being justiciable. In my view the advice given in relation to theprorogation decision is a matter involving high policy and political judgement. This is political territory and decision-making which cannot be measured against legal standards, but only by political judgements. Accountability for the advice is to Parliament and, ultimately, the electorate, and not to the courts.
 I do not accept the submission that the prorogation contravenes the rule of law, and that the claim is justiciable because of that. In my opinion there has been no contravention of the rule of law. The power to prorogue is a prerogative power and the Prime Minister had the vires to advise the sovereign as to its exercise. The executive is accountable to Parliament and the electorate for the advice to prorogue.
 Parliament is the master of its own proceedings, rules and privileges and has
exclusive control over its own affairs. The separation of powers entails that the courts will not interfere. It is for Parliament to decide when it will sit and it routinely does so. It is not for the courts to devise further restraints on prorogation which go beyond the limits which Parliament has chosen to provide. Parliament can sit before and after the prorogation. It has recently, in the Northern Ireland (Executive Formation etc) Act 2019, s 3, exercised its legislative power to make provision about periods when it should sit.”
A similar challenge will be heard in the High Court, brought by Gina Miller and supported by Sir John Major.