No-one could surely have predicted that the Brexit process would be topped and tailed by two highly significant Supreme Court rulings about the ancient prerogative powers of the Crown and the relationship between the executive and parliament.
In 2017, in Miller (1), the court ruled by an 8-3 majority that parliamentary authorisation was necessary in order for the government to trigger the process of withdrawing from the EU.
Today, in an even more dramatic and significant decision, the court has ruled unanimously that the prorogation of parliament for five weeks in the run up to the withdrawal date was unlawful.
In so doing, it has upheld the decision of the Inner House of the Court of Session in Cherry et al, and reversed the decision of the Divisional Court in Miller (2).
According to the court, there were four issues to be decided:
- Is the question of whether the Prime Minister’s advice to the Queen was lawful justiciable in a court of law?
- If it is, by what standard is its lawfulness to be judged?
- By that standard, was it lawful?
- If it was not, what remedy should the court grant?
On the first point, the court decided that the case was justiciable, as the issue before it was one of determining the lawful scope of the power to prorogue parliament, and not simply about the manner of its exercise.
Secondly, the boundaries of the prerogative power were to be determined by reference to fundamental constitutional principles, which in this case meant that it could not be used in a way which had the effect of frustrating or preventing the exercise by parliament of its constitutional functions of enacting legislation and scrutinising the executive, unless there was a reasonable justification for so doing.
Thirdly, according to the court, the effect of such an abnormally long prorogation clearly was to prevent parliamentary scrutiny – doing so, moreover, in exceptional circumstances in which parliament ought to have a voice – and no reasons had been offered why a five week prorogation was necessary.
Finally, the court held that the advice by the Prime Minister to the Queen to prorogue parliament – and everything that flowed from it – was null and void.
Thus, according to the court, the parliamentary session had not been brought to an end, and parliament was therefore entitled to reconvene at a time and in such manner as the parliamentary authorities thought fit.
This was, then, a comprehensive defeat for the government, and an extremely robust defence by the court of the principles of parliamentary democracy.
Nevertheless, although the judgment was compelling delivered, there are a number of sleights of hand in the reasoning which disguise the novelty and significance of the decision, and help the court to resist the accusations of judicial overreach which followed upon the Inner House’s ruling.
The first of these was the recasting of the case as involving a question as to the scope of the prerogative, rather than its exercise.
This helped the court to side-step arguments about non-justiciability. Whereas judges are normally reluctant to interfere in the exercise of government decision-making, particularly on highly politicised issues such as this one, they have been ruling on the scope of prerogative powers since the 17th century.
Secondly, the court placed emphasis on the effects of the prorogation, rather than on the government’s motives for the decision.
Judging the effects of the prorogation was cast as a matter of fact, and again the routine nature of judicial assessments of fact was stressed.
Yet, in assessing whether there was any justification for the unusually lengthy prorogation, the court was necessarily making a value judgment about the appropriateness and weight of the reasons offered.
Thirdly, the court derived from the well-established doctrine of parliamentary sovereignty a novel principle that parliament should not be impeded in the exercise of its legislative functions.
Similarly, it recognised as a legal principle the principle of responsible government, although this has largely been established through convention and not legal rules.
Finally, while stressing the normality of the review exercise it was engaged in, the court made reference to the exceptional nature of the political context to justify the finding that parliamentary scrutiny had been unjustifiably impeded.
At the same time, it downplayed the existing mechanisms – the need for parliament to approve supply, to maintain the armed forces, and to approve government Bills – that would guard against the prorogation power being used to circumvent parliamentary government altogether.
Whatever the holes that might be picked in its reasoning, many people will no doubt welcome the willingness of the court to take on the mantle of defender of the constitution.
Even in the absence of a written constitutional document, the court has in this and other cases, strongly asserted the importance of the common law as a source of constitutional principles discoverable and enforceable by judges.
However, this raises important questions of legitimacy and institutional competence – not least about the nature of the constitutional order being forged by the courts.
As my colleague, Chris McCorkindale and I have observed in examining the numerous cases brought to try to influence the Brexit process, this case fits a pattern of constitutionally-conservative judicial creativity.
In other words, the interventionist decisions that have been made – in Miller (1), in Wightman (the Art 50 revocation case), in the Scottish Continuity Bill reference, and now in Cherry/Miller (2) – have all been directed at upholding the authority of the Westminster Parliament.
Other arguments, particularly those arguing for a more plural understanding of the UK constitution, in which the power of the UK Parliament is limited by the claims of the various devolved territories, or which recognises a constitutional role for the people, have so far met with little success.
It remains to be seen, of course, what the UK Parliament will do with the power that the Supreme Court has handed back to it. It also remains to be seen how far the courts are willing to push their constitutional assertiveness.
The latter question might be tested very soon, since the Inner House has already been asked to use its power under the nobile officium to ensure that the Prime Minister complies with the Benn-Burt Act.