Some legal cases are more interesting for what happens, or does not happen, during the proceedings than for the result. And sometimes it is a piece of evidence, or missing piece of evidence, which can be the most important thing about a case.

On Friday the High Court in London turned down a legal challenge to the planned suspension of parliament for five weeks. A similar challenge in Scotland is still going on. There are likely to be appeals to the UK’s Supreme Court.

Both the legal actions are arguable, and they may ultimately prevail. The Supreme Court could declare that it was unlawful for the government to ask the Queen to prorogue parliament during the run-up to October 31, the date on which the UK is set to leave the EU by automatic operations of law. It is more likely that the justices will sidestep the claim, saying it is “non-justiciable” and a matter for politics not law.

But as with Sherlock Holmes’s dog that did not bark in the night time, there was a strange omission from the evidence put before the court.

The challengers argue that the government had an improper motive in seeking the prorogation. They say that the real intention was a cynical effort to close down parliament, so it could not block a no-deal Brexit, rather than the stated reason that it was merely to facilitate a new Queen’s Speech and the launch of a new parliamentary session.

Usually, there is a straightforward way to rebut, if not refute, such an allegation of bad faith. Those facing such an accusation can, and normally would, submit a witness statement from a senior official or minister setting out the account of how a decision was made, detailing the relevant considerations and the information on which the decision was based. Such evidence, if cogent, defeats such a challenge, unless the evidence can be controverted, or bad faith shown.

But the government did not provide such witness statements in this case. There has been no official explanation. Their absence in this kind of litigation is conspicuous.

There are three possible reasons for this. The first is that a deliberate, prior and tactical decision was made not to put such evidence in. This is possible, though odd. It may be that the government believed that the burden was on the challengers to make their cases, not for the government to say anything.

The second is that the government planned to put in such witness evidence, but something came up to frustrate the process. Perhaps documents could not be found, or unexpected information came to light. Perhaps litigators ran out of time to finalise their draft, or the witnesses, in whose name the statement would be, could not agree on the wording.

All these things are possible, but it must be noted that the government lawyers who handle these kinds of judicial review claims are among the best in the profession.

But there is a third startling possibility. Joanna Cherry, an experienced advocate and the Scottish Nationalist MP behind the case in Edinburgh, has already raised it at a parliamentary select committee, as has former attorney-general Dominic Grieve on the floor of the House of Commons.

Could it be that a witness statement was intended and prepared but that the relevant senior officials refused to sign it? Or that the document contained something the government did not want the court, or the world, to know? Ms Cherry asked Michael Gove, the minister responsible for no-deal planning, about it. He said he had “absolutely no idea”.

Witness statements are formal court documents, and it is a criminal offence to sign one that you know to be incorrect. They are serious documents for serious people, as far apart from the trivial discourse of political sloganeering and promises as one can imagine. Witness statements matter.

The government’s position on prorogation is that the request was made for routine reasons, and not to frustrate parliament. The legal challengers in London say there is evidence that ministers themselves do not quite believe it. But that is the official version.

The government has disclosed some documents which, on their face, show that the prorogation was routine but Ms Cherry and others fear that these do not provide a full account, and that the decision was contained in unofficial communications, such as WhatsApp messages. My own view is that if the government’s disclosed documents were the entire story then a witness statement would not have been a problem.

All this said, if the prorogation was cynical and political, that does not itself mean that it was unlawful: the courts may treat this as a matter for politicians and not judges. And the absence of evidence does not mean that any particular speculation as to the real intentions would be true.

But if the reason for prorogation was not that which was given, then this, regardless of any legal sanction, shows that the current government continues to casually abuse constitutional norms. And that is why our attention must be drawn to the curious incident of the missing witness statement at this time.

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