Appearing before MSPs on Holyrood’s Justice Committee, Simon Brown, vice-president of the Scottish Solicitors Bar Association (SSBA), said that the trials would not be fair and would inevitably result in appeals.

Judges would be perversely incentivised to convict, since it is the lack of convictions in rape trials that forms the basis for the proposals, he noted.

“Therefore, by any objective test, that pilot can only be a success if it does increase convictions because if it doesn’t, then what’s the point of it?”

This, he said, could result in an “unconscious bias towards conviction”.

He added: “People perhaps don’t recognise the interconnectedness of criminal law, and the way that different parts influence on one another.

“For example, one of the reasons for the lower conviction rate in Scotland is the policy taken by the Crown Office in terms of prosecution, because they take the view that in most cases, if there is a sufficiency of evidence, they will prosecute.

“Now, I’m not saying that’s necessarily a good thing or a bad thing. But if you compare and contrast that to England, where there’s a test of a reasonable chance of conviction, you’ll see a much higher conviction rate.”

The SNP’s John Swinney MSP questioned the ethics of the boycott.

He asked why lawyers would “essentially say they are not going to follow the rule of law” if Parliament passes the bill as it stands.

“It’s our job to see that an accused person gets a fair trial,” Mr Brown said.

“If we are faced with a forum, in which we do not think an accused person is getting a fair trial, then we can decide that we don’t want to be part of that. We are all self-employed individuals, we all run our own businesses.

“And we all have the right to pick and choose what work we do.”