Cento Veljanovski was expert in the landmark consumer collective action Walter Merricks v. MasterCard. The collective proceedings order (CPO) application before the Competition Appeal Tribunal (CAT) was only the second under the Consumer Rights Act 2015. Merricks is the largest damage claim in UK legal history made on behalf of over 42 million individuals claiming damages of £14 billion (US$18.2 billion). This is a follow-on action arising from the European Commission’s MasterCard decision of 2007 which found that MasterCard had set excessive default interchange fees. The CAT refused certification, and the class representative has successfully appealed (see above).