Public planning as an administrative function has been neglected in legal studies in recent years. The gap is due to the fact that there was a movement of ascent of the institute in the XX century, with its link to the Welfare State, and its subsequent fall, at the end of the century, in as a consequence of the prevalence of liberal ideals. The fall, however, did not imply in its disappearance. The hypothesis defended in this work, therefore, is that the administrative function of state planning, under the lens of the 21st century, lends itself to the rationalization of public action and leads to innovation. In this context, planning is inserted as a stage of the public policy cycle, focused on the economic-social development of the State, and structured through norms defining plans and policies. Law, planning and development comprise a triangular relationship of complementation, allowing the interaction of legal and extra juridical elements in the conduct of administrative action.