The work deals with the problematization of the theoretical foundation of the principle of the nullity of unconstitutional law in Brazilian constitutionality control. It questions the theoretical sustainability of the assumption that the unconstitutionality of a rule implies the nullity of the law. To this end, it resorts to the theoretical treatment of the material and temporal relationship between law and rule, starting from the contemporary conception of law, which emerged in the codifications, passing through the theories of the rule of Hans Kelsen, Ronald Dworkin, Robert Alexy and Friedrich Müller, authors who are widely accepted in Brazilian doctrine. The question is whether it is possible to theoretically extract, just from the concepts of norm and normative text, the presumption that the unconstitutionality of a norm automatically implies the nullity of a law. It also includes an analysis of the jurisprudential development of the Brazilian Supreme Court in the application of the principle of nullity and the verification that there is a movement to make this principle more flexible, not for theoretical, but practical reasons. The approach criticizes the theoretical bases of the principle.