Mastercard Inc. preyed on more than 46 million unknowing consumers by unfairly charging card fees over a 16-year period, lawyers seeking to bring a 14 billion-pound ($17.2 billion) class-action lawsuit told a London court.

The credit-card company infringed European Union competition law by imposing high charges to retailers that accepted its cards between 1992 and 2008, Paul Harris, a lawyer for consumers, told the Competition Appeal Tribunal Wednesday. The panel will hold a two-day hearing to decide whether the matter should go to a full trial. It would be the U.K.’s biggest class action and one of the first filed under the Consumer Rights Act 2015.

"It is difficult to be able to see why Mastercard should be able to prey on millions of people, what’s more without these people knowing they were being injured," Harris said. "This is the archetypal case that the government had in mind when creating this new regime."


Mastercard has faced numerous lawsuits since EU courts said the company’s fees for cross-border payments unfairly restricted competition. The firm said that a cap imposed by the European Commission on what it charged retailers to process transactions on foreign transactions would shift the burden onto customers, an argument the Court of Justice rejected and opened the door to collective lawsuits from consumers.

The lawsuit was initiated by Walter Merricks, a lawyer who once led the U.K. organization that handles consumer disputes with banks, and Quinn Emanuel Urquhart & Sullivan LLP.

In court documents, Mastercard said the suit should be rejected because the level of damages is "impossible to assess on any reliable basis." The awards allocated to individuals would also "bear no reasonable relationship to their actual loss," the company said.

"Mastercard continues to disagree with the basis of the proposed collective action and we will strongly oppose this claim in the event the court decides to hear the case,” a spokesman said.