An estimated 570 Midland barristers will refuse to take on new criminal work from October in protest against pay cuts.
The action, which could last at least two weeks, is likely to paralyse the region's judicial system as hundreds of child sex abuse, rape and robbery cases are stalled.
The boycott is a reaction to the Government's intention to cut barristers' hourly rates from October 5 for defending in legal aid cases which last up to ten days.
The new legal aid rates could slice up to 30 per cent off the rates, which range between £33.50 and £62.50.
Leading Midland criminal barristers are furious that hourly rates have not risen since 1997, let alone that they are now about to be cut.
Peter Joyce QC, who will become leader of the Midland circuit in October, believes the vast majority of the estimated 600 criminal barristers on the circuit will refuse to appear in court.
He said: "Some of the rates are going to be appalling from October 5. Junior barristers will suffer the worst. Some could earn as little as £46.50 a day. And that doesn't even include their expenses.
"What member of the public would accept that? We are not going to accept work at the new reduced rate. Of course, there will be some criminal barristers who do not agree and will appear in court, but they will be in a very small minority."
Mr Joyce, who works at One High Pavement Chambers in Nottingham, said barristers on his circuit, which includes Crown courts in Birmingham, Wolverhampton, Stafford and Coventry, would not abandon cases they had already taken on, but would instead refuse new work.
He said: "People coming before the court could potentially be unprosecuted and undefended, so they might not get a fair trial.
"But the Lord Chancellor has dug this hole and he has it within his power to cancel these cuts.
"If, however, he persists in his plan to reduce hourly rates for defending in legal aid cases then he will be fanning the
flames of disaster. He will, in effect, be breaking a system that works very well."
Barristers have been warned by the Office of Fair Trading that they cannot go on strike because they are sole practioners and not part of a trade union.
Tony McDaid, who runs No5 Chambers in Birmingham city centre, said: " Feelings of anger and frustration are running particularly high at the moment.
"We are talking about dedicated professionals here. Criminal barristers have chosen criminal work because they want to help the community. It is by no means the most lucrative area and they are being penalised for that." A survey by the Criminal Bar Association found that nationally 97 per cent of criminal barristers back direct action and 79 per cent intend to take it in protest at pay cuts for publicly-funded work.
The confrontation between barristers and the Government over legal aid funding comes at a time when recent reforms and legislation have made cases more complex.
In A Fairer Deal for Legal Aid, a report by the Department for Constitutional Affairs, the Lord Chancellor, Lord Falconer, defends the cuts as a way of providing "fair justice at a fair price" and a means of giving the legal aid system a new direction.
He writes: "The reforms will ensure that, like other mainstream public services, publicly funded legal advice and representation delivers for the public.
"This means guaranteeing that the taxpayer gets value for money from those who provide services with legal aid money.
"When legal aid was introduced in the post-war period, its aim was to provide access to justice and to contribute to a fair and decent society.
"These principles remainy. The vision set out here will see these principles applied to the needs and demands of today's society."