Our study aims to determine whether the theory of state action constitutes an institution comparable in its content and scope with respect to the German theory of the mediate effects on third parties of fundamental rights or, if on the contrary they are institutions of a different nature. In opposition to the horizontal structure of the mittelbare Drittwirkung, state action is valued as the paradigm of the polar, strictly "vertical" approach to constitutional rights, but also as a considerable gap in constitutional protection. It is stated that, between the two, there would be substantial differences in theory and approach that would produce very different results. We will hold that the mittelbare Drittwirkung is not applicable to cases in which there is an impairment of property rights, which constitute the area in which the doctrine of state action has had its origin and development, so a direct comparison would not be possible between both.