THE PRINCIPLE OF LEGAL CERTAINTY IN TAX LAW AND THE INSTITUTE OF CONSTITUTIONAL MUTATION: LIMITS OF JUDICIAL ACTION

Abstract

It aimed to highlight the fundamental nature of the principal of legal certainty and to promote its compability with the constitutional mutation, na institute inherent to the dynamic character of law. The implicit nature of legal centainty principle was emphasized, as well as the fact that it derives from several other principles expressly enumerated in the legal system, such as non-retroactivity, legal, equality, among others. The overarching principal of legal certainty constitutes a state os affaies resulting from the operation of these other principles. The elements that constitute this overarching principle of legal certainty were identified which vary according to different scholars but fall between dterminability/cognoscibility; immutability/ reliability and predictability/ calculability. The research was carried out through the study of renowned legal doctrine in addition to the analysis of case law, it was thus found that there are insurmountable restrictions on mutational activity which, in summary consist: in the observance of the explicit and implicit material limits imposed even on constitutional amendments themselves, as well as respect for the possible meanings of the normative proposition (the norm text) under the penalty of, by failing to do so, constituting an undemocratic conduct due to the lack of observance of the separation of powers; as well as the need for changes, namley that changes in the factual context, which do not amount to informal constitutional change must be stable and constructed gradually. This reflective research aims to draw attention to judicial decisions that make use of the instrument of constitutional mutation and to verify wheter they are in accordance with the dictates of the legal order, and, if they are not, that the appropriate measures provided for, in the legal system be taken. All of this seeks to prevent the establishment in Brazil of na atmosphere that exudes legal uncertainty, which has been occurring in the present context.