The global payments processor is facing a lawsuit brought by consumer champion Walter Merricks on behalf of approximately 46 million adults in the UK, which became the first mass consumer action to be approved in the UK in 2021.

The case was certified last year after a nearly five-year journey from the first-instance Competition Appeal Tribunal (CAT), which initially refused to give the go-ahead, to the UK Supreme Court and back.

In March, the CAT said the date for determining whether members of the claimant class are based in the UK should be when the case was filed in 2016, meaning the claims of roughly three million people who had died since could be continued by their estates.

Mastercard’s challenge to that decision was dismissed on Tuesday by the Court of Appeal, which ruled that the CAT was entitled to take into account that three million people who had valid claims in 2016 would be excluded.

Judge Julian Flaux said the overall purpose of the UK’s collective proceedings regime – roughly equivalent to US class actions – is to “provide access to justice for individual claimants who would not otherwise be able to obtain legal redress.”

He added: “The effect of Mastercard’s case would be to thwart, at least to a significant extent, the overall purpose of the regime.”

A spokesman for Mastercard said: “We will continue to fight it [the case] and are confident that, once the facts are presented in court, the case will be thrown out.”

Merricks’ lawyer Boris Bronfentrinker said: “Mr Merricks is pleased with today’s judgment and looks forward to now prevailing on the merits to secure the billions in damages owed by Mastercard to UK consumers.”

Merricks alleges Mastercard charged excessive “interchange” fees – the fees retailers pay credit card companies when consumers use a card to shop – between May 1992 and June 2008 and that those fees were passed on to consumers as retailers raised prices.