Customers could learn later on Thursday whether banks are to appeal against a ruling that potentially paves the way for current account holders to reclaim billions of pounds in fees.
The High Court ruled in favour of the Office of Fair Trading (OFT) five weeks ago, allowing the consumer affairs watchdog to press ahead with an investigation into whether banks can legally charge customers who slip into the red without prior agreement or who write a cheque that bounces.
The banks and the OFT will meet in court again on Thursday at a case management meeting to set the timetable for the next steps, at which either party is allowed to appeal against the original ruling.
The meeting is expected to last most of the day and could run over into Friday.
If the banks appeal, the case could go to the Appeal Court and the Lords before the full case goes to court -- and that could take two years or more.
If not, it will be up to the OFT to decide whether these "default" charges actually are unfair, and if so deciding upon a "fair" level of charges.
Until the test case is resolved, customer complaints and court cases relating to the charges are on hold.
Martin Lewis, founder of financial website MoneySavingExpert.com, said: "It's hoped the banks won't delay the process further by appealing this decision.
Yet even if they do, the law is now plain and binding: bank charges are governed by fairness rules.
"Therefore, whatever happens in the court, it's time the regulator, the FSA (Financial Services Authority), lifted its hold on reclaiming and gave people a chance to get their money back."
The OFT launched an investigation into the fees in March 2007 after a consumer backlash that saw thousands of Britons claiming back fees going back up to six years.
In the first half of 2007, Britain's biggest banks refunded more than 400 million pounds.
But several banks disputed whether the charges, typically between 24 pounds and 39 pounds per unauthorised overdraft, came under the OFT's remit, triggering the legal dispute.
Mr Justice Andrew Smith backed the OFT, which argues that the 1999 Unfair Terms in Consumer Contracts Regulations can be applied to overdraft charges imposed by the bank and, therefore, the banks can be sued.
But he added this did not necessarily mean the terms imposed by banks were unfair.
Britain's biggest banks say their charges are fair and clear, while analysts and campaigners have estimated they take more than 1 billion pounds in such fees a year.
The High Court ruling follows a January hearing at which lawyers for Royal Bank of Scotland, Abbey, Barclays, Lloyds, HSBC, HBOS, Clydesdale Bank and building society Nationwide argued the 1999 regulations were not applicable to charges agreed between banks and customers.
The eight lenders hold about 90 percent of personal current accounts in Britain.
