The law firm Maurice Blackburn filed on Tuesday a new class action suit before the New South Wales Supreme Court against ANZ, Citibank and Westpac over credit card late fees.

It would also file similar lawsuits versus National Australia Bank, American Express and the Commonwealth Bank. The class action suit, the broadest in Australian legal history, includes all customers of the target financial institutions who had been affected by late fees that Blackburn described as excessive.

It is different from previous lawsuits which were closed or required victims to register to benefit from the claim against the banks. The previous closed action suits have over 180,000 registered claimants seeking damages of $223 million.

The sheer number of potential beneficiaries of the lawsuit makes it hard to provide a ballpark figure on the size or value of the potential claim. It has so far no limit on how far back the alleged overcharges apply, but ANZ will ask the court next week for a time frame.

Maurice Blackburn has the expertise when it comes to these kinds of legal action since it enjoyed a partial victory against ANZ in a Federal Court case initiated in 2010 when Justice Michelle Gordon ruled in February that ANZ's credit card late fees of up to $35 were extravagant and unconscionable when the real cost to the bank of such expenses is only about 50c.

The firm estimates the banks charged customers $604 million as exception fees between June 2099 and July 2010, collected when customers pay their credit card fees late.

The law firm had also initiated similar lawsuits against Citibank, Commonwealth Bank of Australia, NAB and Westpac.

YouTube/NTDTV