North and south of the Border, the courts at first instance dismissed the Miller/Cherry claims in short order as non-justiciable. Miller proceeded directly to the Supreme Court by virtue of the “leapfrog” procedure. Cherry, however, was appealed to the Inner House of the Court of Session, which unanimously held, in somewhat startling language about the circumstances and motives for the advice given to the Queen, that the advice to prorogue, and hence the prorogation itself, were unlawful and thus null and of no effect. The nub of both appeals before the Supreme Court therefore concerned the proper scope of judicial review of the prerogative powers of the Crown (little being said about Brexit, far less the referendum result).
The subordination of the prerogative to statute law has been recognized for at least four centuries. More recently, in the GCHQ case of 1985, the House of Lords held that the exercise of certain prerogative powers might also be judicially reviewable – “justiciable” – provided that their subject matter is not “political” in the sense of lacking “judicial or manageable standards” by which to assess the legality of their exercise. It was in this sense that the lower courts in Miller/Cherry held the advice given by the PM to the Queen in Council on 28 August was not justiciable.
It must now be doubted whether the concept of non-justiciability survives in any meaningful form. In the Inner House, Lord Drummond Young held, first, that “the court had jurisdiction to consider whether the exercise of … a prerogative power is ultravires, or whether such a power is used for a purpose objectively without its intended scope.” His brethren gave little attention to that principle, preferring to infer on the basis of the information before them that the PM had given advice to the Queen for the improper, indeed “clandestine” purpose, of “blatantly [frustrating] the will of Parliament at such a critical juncture in the history of the UK.” But it is the analysis of Lord Drummond Young which seems to have received the imprimatur of the Supreme Court, although the court refrained from explicitly abandoning the “excluded categories” of reviewable prerogative powers set out in by Lord Roskill in GCHQ.
The Supreme Court expressed indifference to the “motives” of the PM. On the other hand, he had given advice to the Queen in the exercise of the prerogative of prorogation. Was his advice, and hence the prorogation, ultra vireson account of being without the legal limits which must apply to any power, statutory or otherwise? Even if it were intra vires, it was still open to the court to review the manner of its exercise, not merely on the well-established grounds of judicial review (with appropriate sensitivity to subject matter) but also upon the basis of a considerably expanded notion of “fundamental constitutional principles”. These principles included the principle, formerly a constitutional convention, of ministerial accountability to Parliament; the widening of the concept of the sovereignty of Parliament to embrace not merely the genuine fundamental principle of the constitution, namely the supremacy of an Act of the Queen in Parliament over all other forms of law, but a far more nebulous notion of the right of Parliament to go about its business unimpeded; and even, according to the Lord President of the Court of Session, “the principle of good governance”, though how and by whom that is to be judged was not explained. For good or for ill, at least until the courts think again or Parliament intervenes, this is now the law.
Jane Smith is a former lecturer in law at Edinburgh University and between 2005 and 2018 was an advocate in practice at the Scottish Bar.