Following a 2007 European Commission infringement decision concerning Mastercard’s multilateral interchange fee (MIF), Mr. Merricks sought to bring collective proceedings against Mastercard. These proceedings sought to claim damages on behalf of 46.2 million people in the UK who were purportedly affected by the MIF. The CAT rejected Mr. Merricks’ request for a collective proceedings order. On 16 April 2019, the Court of Appeal overturned that judgment. It found that the CAT had applied too stringent a test on the quality of the evidence provided at this preliminary stage, and that only a “real prospect of success” was required in order for the collective proceedings order to be granted. Similarly, the CAT had been wrong to consider whether an appropriate method of distributing the aggregate damages existed at this stage. Mastercard has stated that it intends to appeal the case to the Supreme Court. The outcome will have important implications for the UK’s nascent collective proceedings regime.