A recent Court of Appeal decision has reignited the prospects of a £14 billion class action against Mastercard. In a much-anticipated ruling, the court has granted an appeal by Walter Merricks, the representative for over 46 million UK consumers, against Mastercard in relation to alleged overcharging of interbank fees between 1992 and 2008. Taking a broad approach to class certification, the court found that class claimants need show only a “real prospect of success” to secure class certification and do not need to detail how the proposed economic model or damages distribution method would, in due course, be determined.