This article discusses the important implications for UK collective actions for competition law infringements arising from the UK Supreme Court ruling in Merricks v Mastercard in December 2020. The landmark judgment lowers the bar for claims to proceed to trial, a significant outcome not only for this case but also numerous other cases where collective actions had been paused pending the Supreme Court’s ruling on the test for “certification”. While this will be welcome news for victims of competition law infringements and their prospects of compensation, it heightens risks for companies under investigation and therefore exposed to damages actions in respect of “follow-on” claims arising from any infringement decision. This raises the stakes for companies subject to investigations and emphasises the importance of effective competition law compliance programmes.