Today’s Supreme Court judgment on whether parliament was prorogued unlawfully is about much more than the battle between parliament and the government over the Brexit process.
In the coming months and years, the Supreme Court’s unanimous judgment—that the Prime Minister’s exercise of the prerogative power of proroguing parliament and the advice given to the Queen was both justiciable and, crucially, unlawful—will undoubtedly re-define the operation of the separation of powers in the UK constitution.
On whether the matter was justiciable, Lady Hale, President of the Supreme Court, stated that while no prerogative powers are amenable to judicial review “there is no doubt that the courts have jurisdiction to decide upon the existence and limits of a prerogative power”.
The Court unanimously concluded that this case was precisely one that concerned the limits of the power to advise the Queen to prorogue parliament.
With regard to those limits, Lady Hale considered what the effects of this prorogation were.
First, she identified that parliamentary sovereignty, i.e. its ability to legislate, had been impeded.
Second, Lady Hale said—quoting Lord Bingham—that “the conduct of government by a Prime Minister and Cabinet collectively responsible and accountable to parliament lies at the heart of Westminster democracy”.
In the Supreme Court’s view, the primary limit on the power to prorogue is that it will be unlawful if it frustrates or prevents, without reasonable justification, the ability of parliament to carry out its constitutional functions as a legislature.
The Court concluded that this was indeed the effect of the prorogation.
In seeking to avoid politicisation of the case, Lady Hale had previously stressed that it was not about the merits of Brexit.
However, many will be unconvinced by this, not least when she stated that “This prolonged suspension of parliamentary democracy took place in quite exceptional circumstances: the fundamental change which was due to take place in the Constitution of the United Kingdom on 31st October. […] The effect upon the fundamentals of our democracy was extreme.”
The government will find it difficult to rebut accusations that behaved in an anti-democratic manner.
Referring to a memorandum from Nikki da Costa, the prime minister’s parliamentary advisor, Lady Hale stated that this “does not explain why it was necessary to bring parliamentary business to a halt for five weeks before that, when the normal period necessary to prepare for the Queen’s Speech is four to six days”.
The government had failed to provide any substantive justification for the need for a five-week prorogation.
Perhaps more than any other, this part of the judgment will restrict the government’s room for manoeuvre in future.
It makes a new prorogation covering the period over 19 October, when Boris Johnson could be required under the terms of the Benn Act to seek a further Article 50 extension, or over the 31 October Brexit deadline difficult to implement.
The judgment removes a key part of the government’s armoury in its strategy to by-pass a ‘Remainer’ parliament.