Resumen
In the court practice of 21th century the doctrine of the rule of reason is getting more significant despite all the criticism on its behalf in theory. The rule of reason is the essence of this doctrine and one of the crucial elements in the verdicts in the USA and Europe. This rule makes legal restrictive agreements which are not by the law, but improve competition and social wellbeing. In this way, the problems of the law application in Antitrust law in the USA and the Competition law in Europe are overcome. The rule recognizes the specifications of the specific agreement and enables the analyses of the agreement effects. The analyses of court decisions in the USA and Europe law given in this essay, help us understand the way of applying the rule of reason in practice and what are the advantages of this rule compared to per se rule.