The UK Supreme Court hands down an important judgment, allowing a £14 billion opt-out collective proceeding (Merricks / Mastercard)

The long-awaited UK Supreme Court judgment in Mastercard v Merricks (‘the Judgment’) was handed down last Friday morning. The Judgment allows a £14bn opt-out collective proceeding to proceed. The application for a collective proceeding, launched by Walter Hugh Merricks CBE in 2016, is the second in the CAT (following the ‘Scooters’ case in 2017) since the start of the UK’s opt-in class action regime, in 2015. The Judgment gives further clarity on the standard required to certify an ‘opt-out’ class for a collective proceeding in the UK’s Competition Appeal Tribunal (‘the CAT’). The Supreme Court made five specific remarks in its Judgment about the CAT’s decision in the Merricks case, as follows [1]: First, in addition to the overcharge (which the CAT determined was a common issue), the