You could be in line for a £450 windfall from MasterCard

Credit card company MasterCard could be forced to pay out billions to British shoppers, over claims that it pushed up prices in stores.

A lawsuit was launched yesterday over the fees MasterCard charged businesses that accepted its debit and credit cards between 1992 and 2008. These interchange fees, claims the suit, were too high and were passed on to consumers.

And because all shoppers were hit by these high prices, all shoppers could be set for a payout too.

Law firm Quinn Emanuel is handling the case on behalf of Walter Merricks, the former chief financial services ombudsman. And, says the firm, at £14 billion it's the biggest lawsuit in British legal history. Taking advantage of new legislation, it's being filed on behalf of all British consumers - including you.

It's already been established that MasterCard was in the wrong in imposing these charges; it finally lost a ten-year legal battle with the European Commission on the issue in 2014.

During the case, the company itself even argued that the charges were passed on to consumers. And it can't try and wriggle out of that now, says Boris Bronfentrinker, a partner at Quinn Emmanuel.

"Despite arguing that consumers bore the cost of its illegal fees, MasterCard has made no efforts to try to compensate consumers through new voluntary compensation mechanisms," he says.

"The consumer claim is completely consistent with what MasterCard has been saying about who paid these unlawful fees. It is not clear how MasterCard can now turn around and argue the opposite to prevent our case from succeeding."

The law firm reckons that, because the charges have already been found to be illegal, all it has to prove is the amount of money that they cost British shoppers.

And, says Bronfentrinker, "MasterCard has since turned over evidence (witness statements and expert reports) that allows us, even at this early stage, to robustly value the claim at £14 billion."

MasterCard is still trying to justify the fees.

"Of course, there are costs to making a payment. In our system, those costs are shared by those who benefit from the payment," says Mark Barnett, division president, United Kingdom and Ireland for MasterCard.

"The retailer, the retailer's bank, the card issuing bank and MasterCard all contribute towards the cost of our network."

The case is likely to come to trial in 2018 - unless, says Bronfentrinker, MasterCard makes consumers a reasonable offer beforehand. However, MasterCard points out that similar cases have been brought in the US with very little success.