The legal assessment about the unconstitutional stare decisis is a challenge for TheScience of Law. The theme reveals the impossibility of the res iudicata, formal or material, opposes against the Federal Constitution and the difficulties that may eventually come due the principle of legal security and Court surety. Indeed, it is possible in legal terms challenge the judicial decision which conflicts with the State’s highest law. In Brazil, Article 5, XXXVI of the Federal Constitution only protects the intangibility of stare decisis with regard of retroactivity of law which could be review or even reversal individual rights. Nevertheless, if a judicial sentence eroded a constitutional precept, the Brazilian Criminal Procedure Code as also the Code of Civil Procedure, predicts mechanisms to nullify decisions guaranteed by a pronouncement by the Judiciary Power and ends its effects. This article presents the doctrine about this juridical discussion as well as evaluates the available instruments in Comparative Law to attack the immutability of res iudicata contaminated by the worst nullity: the unconstitutionality. In this vein, this text will highlight the jurisprudence of National High Courts to conclude the necessary submission of all state acts —executive, legislative or judicial— to the Constitution, including the stare decisis, which judgments has already been definitively decided and the issue cannot be litigated again. Proclaimed the vertical incompatibility in the face of Lex Magna, the stare decisis must be nullified and operate ex tunc effects as the only way to ensure the normative force of the Constitution.