Behind the subject of this study: “the legal status of mixed public utility companies” there is an analysis of the homogeneity of the system of public domiciliary services from its constitutional foundations, as well as a reflection on the transformations of contemporary administrative law. It outlines the gradual introduction of changes to the referred legal system, by the constitutional and administrative jurisprudence, many of them, discordant with the constitutional foundations of public services or utilities, especially of the so-called “economic Constitution”.