The paper retraces the constitutional jurisprudence of the past decade with regard to the protection of competition. Assuming that the Article 17 (2)(e) is not interpreted by the Court as a mere rule on jurisdiction but as a substantive rule, the a. agrees with the fundamental assumption of the Court that the «protection of competition» falls within the exclusive «transversal» competence of the State and may affect the discipline of any economic sector. Nevertheless, the a. claims that the Court is not always coherent at the time of developing the aforementioned assumption. Indeed, the thesis of the «transversal» competence would require an accurate and purposive definition of the concept of «protection of competition»: as stated by the a., this definition is absolutely possible, although it is still missing within the jurisprudence of the Court. Furthermore, the concept of «protection of competition» is intended by the Court in a sole objective sense with reference to various aspects (in particular, the discipline of public contracts). The analysis ends with the examination of the effects of the protection of competition on the activities of public companies and on the possibility that different kinds of social purposes may justify a derogation to the principle.