London court on Wednesday approved a 10 billion pound-plus ($14 billion-plus) class action against global payments processor Mastercard (MA.N) that claimants said could entitle 46 million British adults to roughly 300 pounds each if it is successful.

The Competition Appeal Tribunal (CAT), which had previously rejected the lawsuit, formally certified it on Wednesday allowing the case to proceed to trial as the first mass claim to be launched under the Consumer Rights Act 2015. The legislation is intended to compensate consumers and small businesses for anti-competitive behaviour.

The decision to finally authorise the five-year case as a collective action establishes a standard for a string of other proposed class actions that have been stalled in its wake.

"Mastercard has thrown everything at trying to prevent this claim going forward, but today its efforts have failed," former financial ombudsman Walter Merricks, who brought this case, said in a statement.

"The tribunal's ruling heralds the start of an era of consumer-focused class actions which will help to hold big business to account in areas that really matter."

Mastercard said the "spurious" claim was being driven by lawyers and backed by organisations "primarily focused on making money for themselves".

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.

The case against Mastercard stems from a 2007 European Commission ruling that interchange fees for the use of Mastercard debit and credit cards were in breach of competition law.

The tribunal has now ruled that Merricks’ lawsuit cannot include a claim for compound interest and cannot include claims from the estates of consumers who died between 1992 and 2008.

According to Mastercard, this reduced the claim's size to around 10 billion pounds which as per the claimants was 15 billion pounds.

"The decision today reduces the value of this spurious claim by more than 35%," Mastercard said in a statement.

"Mastercard is confident that over the coming months a review of key facts will further significantly reduce the size and viability of the claim."

Lawyers said that the case was a major development for UK litigation.

Image source:  Reuters