A number of judges have raised the issue of poor evidence being offered during mitigation pleas.

Judges, especially those in the Circuit Court, have said lawyers are making claims such as that their clients suffer from mental conditions – without providing corroborating evidence.

Concerns have also been raised over the quality of evidence, particularly the practice of handing up unsigned documents as proof of a claim.

Mr Justice John Edwards in the Court of Appeal made the strongest criticism in June, when he “put down a marker” that barristers must supply evidence of anything they want to rely on in sentence hearings.

The judge said that barristers giving evidence on a hearsay basis was “happening all the time” and “has to stop”. He was critical of barristers for asserting that offenders suffered from depression as well as addiction and trauma.

Mr Justice Edwards warned them such practices must cease.

“This court is putting down a maker, that has to stop. If people are relying on matters in mitigation there has to be evidence of it.”

One defence barrister told the newspaper: “You are less likely to get away with just saying ‘my client has depression’ or ‘my client’s mother is very sick’ unless you have a document or witness to back that up. It still happens but it is slowly changing.”

Another said clients usually insist on such claims being made.

“A lot of us will actually welcome [Mr Justice Edwards’ judgment] because we can point to it and tell the client ‘look we can’t make that claim without evidence’.”