Is that enormous silver spider that Lady Hale wore her badge of office? If so, it is appropriate. The Supreme Court has decided to tie up the government in a web of legal reasoning so tight that it can no longer govern. In his dissenting judgment in the earlier Miller case about Article 50, Lord Reed warned that ‘the legalisation of political issues is not always appropriate and may be fraught with risk, not least for the judiciary’. Unusually — as if to compensate for these words — his name was joined with that of Lady Hale in giving the judgment on Tuesday. He would have done better to heed his own earlier warning. They are in deep now.

The very first paragraph of the judgment gives the Supreme Court’s game away. This is not about ‘when and on what terms’ we leave the European Union, it says, but it goes on to declare the case is ‘a one-off’, in circumstances which are ‘unlikely ever to appear again’. It is the court’s way of saying that it is justified in tailoring the law in response to its perception of a political crisis. This is developed in paragraph 50: ‘A decision to prorogue parliament (or to advise the monarch to prorogue parliament) will be unlawful if the prorogation has the effect of frustrating or preventing, without reasonable justification, the ability of parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the executive.’ In these words, the court leaps from rightly policing the borders of the prerogative to deciding whether some exercise of the prerogative is reasonably justified. The word ‘prerogative’ thus becomes meaningless. The judges have decided they own it.

In doing so, they are turning themselves into our constitutional court, which they aren’t. If that is what they want, they must accept the terms which go with it, as in the United States. The public must have a right to know their private opinions — their religious beliefs, for example, or how they voted in the Brexit referendum. They must also be selected and vetted by more open means. It’s Hale and farewell to the court’s reputation for impartiality and the respect that goes with it. Having failed to understand the doctrine of the Crown in parliament, and decided instead that we live in the 17th century under the dictatorial power of the King (now in the shape of Boris Johnson), they have appointed themselves arbiters of the actions normally reserved to government and parliament. As Boris tries to implement the largest popular vote for anything in British history, voters may struggle to see how he resembles King Charles I.

As one reads on through the Supreme Court judgment, its prosecuting tone becomes more insistent. It sweeps aside, almost without consideration, the earlier judgment of the Divisional Court. Did Mr Johnson’s action in proroguing frustrate the constitutional role of parliament? ‘Of course it did,’ it exclaims in paragraph 56, short-circuiting the sober argument it should itself make out. Although Lady Hale and Lord Reed protest that they are passing no judgment on the motives of the Prime Minister (paragraph 58), they say three paragraphs later that it is ‘impossible for us to conclude… that there was any reason — let alone a good reason’ for Boris to have advised the Queen as he did. That is insinuating Ciceronian rhetoric — not judicial, and not judicious. ‘It follows that the decision was unlawful,’ they continue, thus creating a new doctrine that the exercise of the prerogative requires, by law, that its reasons be good to the satisfaction of the court.

Our law sometimes deploys the concept of the ‘reasonable person’. Lord Sumption now says that the judges’ ‘revolutionary’ act was justified because if something is ‘sufficiently shocking, you must expect people to change the ground rules’. But would the reasonable person really think, as these judges do, that proroguing parliament for a few more working days than would have been the case if it had risen only for the party conferences has ‘such an extreme effect on the fundamentals of our democracy’? Might the reasonable person not have noticed that, even before prorogation, parliament was doing extremely little other than saying ever more noisily what it had said before? Now they’re at it again. The truly shocking change of the ground rules, from which all else flows, was Mr Speaker’s decision to remove government control of the business of the House.

In 2014, the think-tank Policy Exchange was attacked for setting up its Judicial Power Project. It was ‘irrelevant and niche’, said its critics. In fact, Policy Exchange and the unit’s outstanding head, Professor Richard Ekins, had identified and today continue to monitor one of the most insidious changes in the West which British conservatives had badly neglected — the way the noble concept of the rule of law has been degraded into something quite different, the rule of lawyers. It is a prime example of what economists call ‘producer capture’. The victims are the voters.

So what should Boris Johnson do now? Obviously the law officers are twitchy. They defer to judges and their later careers may depend on them. But as the judges make much of not impugning Boris’s motives before going on to savage him, he is perfectly entitled to employ the same technique. Boris can say that the Supreme Court and Mr Speaker between them have contrived, in the name of democracy, an arrangement by which democracy cannot operate. Parliament has no confidence in the government, but refuses to vote to say so because that would provoke the election which Labour and Remainers fear. I come back to that spider’s web. Boris resembles Sam Gamgee in Shelob’s lair, and only he, armed with Frodo’s dagger Sting, can cut their way out. For Sting, read a general election.