Read more of Frances Gibb's exclusive online columns

It takes just one high-profile and emotional case to make the point.

The teenager accused of murdering the schoolboy Rhys Jones in Liverpool has been left without a QC to defend him with only one month to go before trial.

The reason is the current wrangle over legal aid rates for the so-called "very high cost cases", the most serious trials to take place in the criminal courts.

The Bar has already issued warnings that the trials — involving murder, rape, terrorist offences, drugs and fraud — are at risk because of the ongoing dispute over fee rates, which has seen hundreds of barristers failing to sign up to the new special panel to handle the work.

Now, at a hearing just last week at Liverpool Crown Court, it emerged that the Rhys Jones trial, currently scheduled for October 2, may have to be adjourned.

Rhys was shot dead in August last year, aged 11, as he walked home from football practice. The defendant is one of seven accused who will stand trial. The 17-year-old's lawyers, James Benson & Co, have instructed Jonathan Duffy, an experienced but junior barrister from New Bailey Chambers (Liverpool and Preston) who represented the defendant at the pre-trial hearing.

But the Legal Services Comission has classed the trial as a "very high cost case", which means that it will only pay a barrister from its panel. James Benson & Co is preparing to challenge the decision later this month in a judicial review. Unless a solution can be reached, it will argue that the case has been wrongly classified.

Such a public showdown would be embarrassing for the Comission.

It can reasonably argue that it would be normal for a QC to take a case as serious as this one. Richard Marks, QC, the circuit leader of the northern circuit, told The Times that it would "absolutely unheard of" for a murder defendant in this type of case not to be represented by a QC.

Yet only two QCs and 108 other barristers out of a possible 2300 criminal barristers in England and Wales qualified to do the most serious cases signed up to panel rates of pay.

For preparation work, the rates range from £70 to £100 an hour for a junior acting alone; from £79 to £127 for a leading junior; and from £91 to £145 an hour for a QC. For the day in court, a QC will be paid £476 a day, a leading junior £390 and a junior or acting alone £285.

The Legal Services Commission is defending its position. It says that it "recognises the importance of the trial of those accused of murdering Rhys Jones to his family and the local community" and says it has been "working hard to ensure that there are solicitors and barristers available for all seven defendants".

Six of the defendants, whose solicitors were members of the "high costs cases" panel, had full defence teams of solicitors and barristers. But one solicitor only informed the Commission late that the QC they had originally appointed had withdrawn from the case.

Very high cost cases are those estimated to last more than 40 days. They are the most serious and most costly in terms of legal aid. Last year they accounted for about 100 cases, at a cost of £100 million a year.

Defence teams are typically paid some £400,000 for such cases but in some the cost, the Commission says, have run to millions of pounds.

The Commission adds: "To put this in context, last year the LSC funded advice and representation for nearly 1.6 million defendants. About 120,000 of these were crown court cases.

"The cost of the very high cost cases was approximately nine per cent of the criminal legal aid budget — a total of £105 million out of total legal aid expenditure of £1.2 billion for criminal representation."

But the temperature over the rates of pay is rising. Peter Lodder, QC, who has just taken over as chairman of the Criminal Bar Association, said: "It is very troubling that there is such a serious case there is not a suitable representative available and that this may cause delay."

Nor, he added, was the case likely to be an isolated one. A huge drugs conspiracy trial involving 24 defendants is due to be heard at Woolwich crown court in April and there again, solicitors want to instruct QCs who are not on the panel list.

It is almost one year since Tim Dutton, QC, then incoming Bar chairman, gave warning that the moves to curb barristers' fees in the heaviest trials would lead to a two-tier system, with the top QCs abandoning these cases and moving to only doing private work.

Lodder says that a compromise formula is urgently needed. This would cover the next nine months pending agreement between the Commission, Ministry of Justice, Bar and Law Society on a new scheme which has been promised for very high cost cases to run from July.

Without it, Dutton's words will have come home to roost: defendants on the most serious cases could go without experienced representation with the risk that miscarriages of justice may result.

Times Recommends

• Future Stars of the Bar 2008
• Lawyer of the Week: Julie Morris
• Charging suspects - why it's a job for prosecutors