The U.K. Supreme Court has handed victory to a group of British retailers (the “respondents”) in a long-running dispute with Mastercard and Visa Europe (the “appellants”) finding that the default “multilateral interchange fees” (MIFs) set by Mastercard and Visa and charged by institutions that issue debit/credit cards to customers (the “issuers”) to institutions that provide payment services to merchants (here, the retailers) (the “acquirers”) restrict competition. This judgment (which we previewed in “Competition Litigation Update”) could have significant consequences beyond those involved in the case, including in relation to follow-on damages actions by other claimants (and potential claimants) who may take comfort from this decision. In its judgment, the Supreme Court dismissed three of the four issues on appeal holding, in particular, that MIFs were a restriction of competition contrary to Article 101(1) of the Treaty on the Functioning of the European Union (TFEU) not exempted under Article 101(3). This judgment ends a chapter in one of the most high-profile follow-on damages disputes (and pieces of litigation) in the English Courts of recent years. Determination of the quantum of damages payable will follow (absent settlement).