A major fraud trial is likely to collapse because high-earning legal aid criminal barristers are boycotting defendants after a 30% cut in their fees. It would be easy to mistake this for a great victory in the war to preserve access to justice. The rebel standard flies over enemy territory. But when the smoke clears, it will be seen that although there has been a small advance on one short front, the great mass of little people have gained no ground.

A stand-off between the Legal Aid Agency and some of the country's top criminal barristers has been brewing since last September when the cut was announced. This is the first very high-cost case to be affected by it, and it is the first test of the unofficial boycott, which meant solicitors for the five defendants failed to find a QC available and willing to work for the reduced fee. This is a big, complex case involving 10,000 pages of evidence and thousands of lines of spreadsheets, likely to take three months to prepare and three months in court. Nor could the new public defender service provide enough suitably experienced lawyers to do the job. And that is why one of the most eminent criminal silks, Alexander Cameron, who is also the prime minister's brother, persuaded the trial judge that as the defendants could not be properly represented the case should be stayed. It is a highly unusual ruling that may threaten many more fraud cases in the pipeline.

The Ministry of Justice argues that the QCs would still have earned £100,000. It is a great deal of money, but the MoJ never acknowledges that barristers earn fees, not salaries, and fees have to cover every cost incurred, from shoe leather to stationery to the hours spent in preparation. This particular battle is one that's been lost before, when the Labour justice secretary Jack Straw also tried to rein in very high-cost case fees. It may well be lost again. This is a small group of highly trained people and without them the new Financial Conduct Authority – whose first prosecution this was – will struggle.

Lawyers, meanwhile, declared the ruling should be a wake-up call for government. It is certainly a rare and vivid illustration of the crisis in publicly funded law that is being played out off stage, in family courts where divorcing couples represent themselves, or in criminal ones where witnesses go uncalled. Even worse are the cases that should happen but don't – cases where benefits wrongly withheld go unchallenged for lack of advice, or housing cases where there's no support to compel a landlord to make repairs. The important point about the prime minister's brother firing a broadside at government policy is not in the theatre of Cain and Abel, it is in the demonstration of the old truth that where rights are not protected, there are no rights at all.