In the EU, activities of the liberal professions (legal, medical, technical and accountancy professions) are subject to self- and state regulation. Traditionally their regulatory schemes have been legitimised on the basis of the societal role liberal professions assume, dismissing EU competition law as a means of addressing restrictions in professional services markets. Reflecting on the role of professional associations in rule making processes, this book assesses the authority and democratic legitimacy of professional rules with a comprehensive rereading of the principles governing EU competition law (including Article 102 and 106(2) TFEU). As a result, this book challenges the use of a diffuse public interest concept and the dichotomy maintained in past legal writing between competition and non-economic interests in professional regulation.