The Court of Appeal is hearing a legal challenge against a judge's decision to halt a serious fraud trial after the defendants said legal aid cuts meant they could not find barristers to represent them.
The Financial Conduct Authority, which is prosecuting, is seeking to overturn the ruling by Judge Anthony Leonard.
Legal aid fees in England and Wales have been cut by up to 30%.
This has seen many barristers refusing to take on long or complex cases.
Leading judges Sir Brian Leveson, Lord Justice Davis and Lord Justice Treacy are being urged to overturn the decision taken by Judge Leonard to halt the case.
Judge Leonard had heard the prime minister's brother, Alexander Cameron QC, successfully argue that the case should be halted because five of the eight defendants in the case could not find barristers of "sufficient competence".
The trial, involving the alleged mis-selling of land by Plott UK Ltd, European Property Investments Ltd and Stirling Alexander Ltd between 2008 and 2011, is a so-called Very High Cost Case (VHCC).
Fees for such long and complex cases have been cut as part of Ministry of Justice plans to trim its £2bn-a-year legal aid bill.
Barristers have since been refusing to take on the most complex cases, which run up high costs due to the amount of preparation and court time they involve.
In their search for suitable representation, the defence team contacted 70 chambers. Only one barrister put himself forward, but later withdrew his services.
Judge Leonard said he had no reason to think the defendants would be able to find suitably qualified barristers and it would be a "violation" of the legal process to allow the prosecution to proceed.
But the FCA told the appeal hearing that Judge Leonard's decision had been "unreasonable" and should be reversed.
Attempting to overturn Judge Leonard's order, Sean Larkin QC, for the FCA, told the Court of Appeal it had the power to confirm, reverse or vary the decision to stay the proceedings.
He said: "The judge erred in principle and came to an unreasonable decision. We want you simply to reverse the stay and that will have the effect of this matter going back before the judge at some time in the future for him to consider how best to progress the case."
He argued that the public interest required a lesser remedy - an adjournment - in the case.
Sir Brian Leveson said it was not the court's job to get involved in the dispute between the barristers and the government.
He said: "We are simply concerned in this case with whether the judge was entitled to reach this conclusion at this time on the evidence then before him."
The stand-off over fees could affect other fraud trials due to take place. The FCA has said four defendants in a trial scheduled for September are currently unrepresented, and the Crown Prosecution Service has three fraud-related cases in which there are also no defence barristers.