The latest warning comes after solicitors had been considering escalating their protest over the proposed reforms, amid concerns about the impact on criminal courts and access to justice.

In a statement, Law Society president Rosemarie Loftus said Jim O’Callaghan had written to the society confirming he intended to press ahead with the new payment model “regardless of the serious concerns the legal profession has raised”. The contents of the letter were relayed to hundreds of criminal law solicitors at a meeting of the society’s Criminal Law Committee on 29 June.

Ms Loftus said the Society understood that solicitors across the country were now resigning from criminal legal aid panels, warning the move would have a “devastating impact on access to justice”.

She said victims of crime would face delays to trials, while vulnerable defendants, including children, people with addiction or serious mental health conditions, victims of trafficking and homeless people, would be disproportionately affected.

The society also criticised the Department of Justice for failing to provide exemptions for cases involving particularly vulnerable people or proceedings that typically require greater levels of work, including cases involving children and defendants with mental health or capacity issues.

Ms Loftus described the reforms as “a cost-cutting exercise dressed up as reform”, arguing they were based on flawed assumptions rather than evidence. She said the department had already acknowledged the scheme would require revisions in the autumn, which she said demonstrated it had been introduced before the necessary groundwork had been completed.

She also rejected the department’s assertion that there had been extensive engagement with the profession, saying the Law Society first learned of the flat-fee proposal in February when it was invited to make a submission, before a press statement announcing the changes was issued later the same day.

“The Law Society’s position is unchanged and clear: any reform of criminal legal aid should be workable, fair and evidence based. This proposal is none of those things and the fundamental concerns the Law Society has outlined have not been addressed,” Ms Loftus said.