The current movement of deregulation of professional services in Europe rests on the idea that reducing professional regulation will increase market competition and lead to cut prices for customers. Studying liberalization of the market for legal services, we assume that competition relates much more to quality than to the sole prices. Endorsing the perspective of economics of convention, we show that the profession of lawyer overlaps with a diversity of autonomous and dis-tinct logics that links the quality of services valued by clients with professional practices. These typical logics frame different rational processes characterized by the implementation of distinctive interpretation and reflexivity processes by lawyers. Given that the market-based rationality of maximizing profit sustains only one of the fourth logics embodied within the legal market, this article questions the consequences of professional deregulation on the performance of the market for legal services.