The UK Court of Appeal overturns the Competition Appeal Tribunal’s refusal to certify a collective action claim (MasterCard / Merricks)

In its judgment of 16 April 2019 the Court of Appeal overturned the Competition Appeal Tribunal's (CAT) decision refusing certification in the MasterCard collective action claim and remitted the case back to the CAT for a re-hearing. The CAT's refusal to certify the claim and grant a Collective Proceedings Order (CPO) had been based on two principal reasons: the lack of availability of the sort of data that would be necessary for the applicant to prove that any overcharge had been passed on to consumers and the level of this, and the fact that the CAT did not see a plausible way of calculating the loss each individual claimant suffered at the distribution stage. On the issue of overcharge, the Court of Appeal held that the CAT's approach to the expert evidence was based on a