The seminar is devoted to alternative legal ways in enhance competition policy enforcement towards large digital platforms and their ecosystems. Effects-based, or rule of reason competition enforcement that requires case-specific economic analysis shows limited effectiveness due to excessively lengthy decision-making process, which is not always compensated by the decrease of legal errors. The presentation of Professor Y. Katsoulacos (Emeritus Professor, Athens University of Economics and Business, Affiliated Chair Professor, Jiangxi University of Finance and Economics (JUFE), former Commissioner of the Hellenic Competition Commission, Chair of Scientific Committee and Coordinator of Competition and Regulation European Summer School and Conference CRESSE www.cresse.info), classifies the main approaches to reform in terms of changing the substantive standard of competition law, the legal standard, reallocation the burden of proof in competition cases, as well as in terms of the choice between ex ante regulation and ex post law enforcement.