ANZ customers have recorded a partial victory in their multi-million-dollar class action against the bank, with the Federal Court ruling that late payment fees on credit cards are a breach of contract.
However, the claims against other types of bank fees were dismissed.
Justice Michelle Gordon on Wednesday ruled that $25-$45 honour and dishonour fees, over limit charges and non-payment fees were allowable.
The case is the first of eight class actions brought by law firm Maurice Blackburn on behalf of more than 180,000 ANZ customers.
In her ruling, Justice Gordon agreed that ANZ was improperly imposing penalties on customers with its late-payment fees.
Those fees were described as "extravagant, exorbitant and unconscionable".
ANZ admitted that it was not permitted to charge such fees under the contract, Justice Gordon said.
Justice Gordon said the other fees were not a penalty and therefore not a breach of contract.
Affected ANZ customers who are part of the class action will be entitled to be awarded damages.
ANZ chief execeutive officer for Australia Philip Chronican said he was pleased the Federal Court found that honour, dishonour, overlimit and non-payment fees were not penalties.
"The implications of today’s decision for ANZ and its customers are still far from clear and it is likely to be some time until this matter is finally resolved,” Mr Chronican said, commenting on the late payment fees.
"I don't know if there are any winners out of this," Mr Chronican told reporters.
Mr Chronican said the bank would repay customers if necessary.
The bank had charged late payment fees as they necessitated a series of actions by collections staff, he said.
Decision a huge victory: Maurice Blackburn
Maurice Blackburn lawyer Andrew Watson said the firm would decide whether to appeal over the other types of bank fees and make an announcement shortly.
"Today is, on any analysis, a huge victory," Mr Watson told reporters.
"Late payment fees charged by all the banks will likely be found unlawful."
He said the bank fees in question predominantly are paid by people on lower incomes.
In a statement to the Australian Securities Exchange, litigation funder Bentham IMF said it believes late payment fees represent approximately 25 per cent in value of all claims brought by class action members of ANZ.
The same percentage is likely to apply to all other major banks, except Citibank where late fees are expected to make up more than half the claim, the litigation funder said.
"IMF will seek to expedite recoveries in respect of late fees from ANZ and all the other banks," the funder said.
"IMF will evaluate the impact of the judgement in respect of the other banks, and advise the market accordingly."