Sixty-four mock juries were set up for research, featuring a total of 863 participants. Half of them were shown a recorded rape trial while the remainder were shown an assault trial performed by actors in the High Court in Edinburgh.

The researchers found that, in 48 juries, the members of the jury took body language into account when making their decisions. In the rape trial, an accused’s credibility was doubted by a juror because he “kept looking away”.

Another witness’s credibility was put in doubt because his “neck was straining” or “[he] kept licking his lips”.

Professor James Chalmers and Professor Fiona Leverick, of Glasgow University, and Professor Vanessa Munro, of Warwick University, said their findings, despite using mock juries and actors, could imply miscarriages of justice were occurring due to the interpretation of body language.

They stated: “That the jurors drew on body language in this way is perhaps unsurprising, as they had been specifically directed by the judge to do so.

“The confidence with which jurors [wrongly] pointed to particular aspects of body language as signifying veracity or deception was, however, remarkable.

“Such assumptions run contrary to the prevailing view in the research, which is that witnesses can be nervous when testifying for all sorts of reasons unrelated to their veracity.

“The implication of jurors placing unfounded weight on such cues is that we risk inaccurate verdicts.”

They said judges should stop telling juries to take body language into account in the course of their deliberations.

In their paper, published in The International Journal of Evidence and Proof, they said: “Directions should explain to jurors why they should not take particular factors into account in their credibility assessments, such as eye contact, by pointing to research evidence that they have no relationship with veracity.”

Criminal silk Thomas Ross QC told our sister publication Scottish Legal News: “I do not intend any disrespect towards the academics who put a great deal of thought and time into the development and conduct of the study.

“That said, let us be clear at what is being discussed in this article — pretend jurors assessing made-up accounts given by actors. The volunteers in the project were ‘jurors’ in the same way that Joe Pesci is a US trial attorney: they were playing at being jurors.

“Nobody had been harmed — nobody was going to jail — and they had none of the real life emotional pressures that real jurors must labour under.”

He added: “The jurors knew that they were assessing a made-up account narrated by an actor. If that actor was fidgeting or licking his or her lips, as there was absolutely nothing for an actor to be nervous about, then presumably the pretend jurors could easily discount nerves as an explanation. They might think that the physical tick had been put on to test whether they noticed it.

“Ever since the Scottish government proposed the suspension of juries in a bill in April 2020, the propaganda in the press had been unrelenting. We have reached the stage where the conduct of pretend jurors in a small sample of pretend trials is being used as an argument to abolish the biggest protection that a citizen has from the excess of the state. The fact that he or she will be tried by ordinary members of the public.

“We have a jury system that has been copied the world over. We should be proud of it and not seeking to replace it with the trial system in North Korea and Saudi Arabia.”