Our January 2011Casenote Counterfactual in Competition Cases – Its emergence in European and UK competition law looks at the growing use of the counterfactual. The term counterfactual has not been a feature of European competition law, with the exception of merger control, to date. However, with the move to an effects-based approach, counterfactuals are being used occasionally, hesitantly and with mixed results. This Casenote examines the use of counterfactuals in ‘behavioural’ competition law investigations based on a review of UK and EC competition guidelines, decisions, and several leading UK cases. The Casenote is based on a more detailed analysis in an article entitled ‘Counterfactual Tests in Competition Law’ Competition Law Journal, 2010, Vol. 9.