Modulation and abstrativização diffuse effect: case study

This article aims to discuss, from de decision's effects modulation on the constitutionality control, the possibility of discretionary action of the Judiciary. Submitted the diffuse and concrete constitutionality controls, as well as the decision's effects modulation that recognize the (un)constitutionality, it follows for a concrete case analysis, the Extraordinary Appeal 197.917/SP, in which the Supreme Federal Court has modulated their decision's effects. Even dealing about diffuse constitutionality control, where is adopted the theory of nullity, the Supreme Federal Court has decided by applying the "for the future effect", arised from the concrete constitutionality control. Thus, using the phenomenological-hermeneutic method, part on the basic premise that the diffuse effect abstraction may be maleficent to the whole society. From this initial premise some conclusions arises, among wich that those who did not were part of the lawsuit and had no right to the contradictory and full defense may suffer the decicion's effects. It also concludes, that the modulation seem to indicate an activist stance of the Judiciary, which without explicit criteria for their decisions's effects definition, control the constitucionality disposed into discussion.