The Federal Court of Australia will rule today on the first stage of a class action brought by 34,000 claimants against ANZ over its penalty fees. Justice Michelle Gordon is expected to release the ruling in Melbourne at 9.30 am.The plaintiffs are claiming around A$50 million in compensation for the bank's alleged overcharging of a range of penalty and dishonour fees over six years. IMF (Australia) is funding the case.Today's judgement will determine whether the case is tried under the law of equity, as the plaintiffs argue it should be. The ANZ wants the case determined by the legislation on unconscionable conduct.The substantive issues such as the merit of charges levied and their relation to actual costs incurred by the bank will be dealt with next year. The disputed charges were incurred on overdrawn accounts, bounced cheques and more than a dozen other types of payments.IMF (Australia) has a database of nearly 200,000 more bank customers, and follow-up class actions are likely against other banks and credit card providers if the ANZ action proceeds.