A $7.25 billion settlement between millions of merchants and the Visa and MasterCard credit card networks over fees and anti-steering rules that bar retailers from charging different prices based on the means of payment was thrown out Thursday by a federal appeals court.

The U.S. Court of Appeals for the Second Circuit vacated an antitrust settlement approved by a lower court, finding that one class of plaintiffs were inadequately represented in violation of both the rules for certifying a class action and the due process clause.