Since the general repercussion became a requirement for admission of extraordinary appeals in the Supreme Court (STF), this type of appeal has been paving the way for questions of great national interest to reach the Court and affect a significant number of interested parties.

The introduction of the requirement also highlighted the role of the Supreme Court as a constitutional court. It happens that, once the general repercussion of a matter is recognized, the analysis of the theme of the judgment of the specific process suffers a shift. First of all, the Supreme Court takes the decision on the constitutional subject of general repercussion without limiting itself to the grounds set out in the apeal. The court may receive contributions from representative entities (amici curiae) with notorious knowledge on the subject and, after, apply the understanding to solve the individual process.

This new model of trials related to topics of great interest bears similarity with abstract and concentrated control of constitutionality. Only after the end of this phase, the solution will be applied to the specific case that allowed the arrival of the matter to the Supreme Court.

The underlying effects of decisions given under this system are binding for all courts. After the court of second degree applies the decision, will not be accepted an extraordinary appeal, being possible the handling of complaint against the decision of the court of 2nd degree (provided that exhausted the ordinary instance) that does not apply the position established by the Supreme Court in the general repercussion.

It is even possible to see an important change related to the constitutionality control exercised by the Supreme Court in recent years. Decisions given in the trial of subjective processes, but according to the regime of general repercussion, begin to have an effect similar to those originated from abstract and concentrated control.

This new way of looking at the role of the constitutional court stems from the attribution of the so-called transcendent effect to supreme court decisions in control of diffuse constitutionality, especially when marked by abstractivization.

The manifestations of the Supreme Court are of interest to the entire collective and significantly impact in society, which is why the effects are usually considered in decisions.

The Supreme Court does not act in an airtight manner or even without considering the events that occurred in society – although it is frequent to try to refute this statement – especially because, when interpreting the constitutional provisions applicable to the cases under its assessment, the conceptions that prevail at that time are taken as premises.

However, claiming the influence of extralegal factors in the application of law requires some care, otherwise the Judiciary takes on a typical function of the Legislative Power.

In relation to the control of constitutionality of laws that create or modify the rule of a tax, the argument that the declaration of unconstitutionality may have a relevant impact on public accounts and compromise the federative person's ability to continue activities of interest to the population is often raised (sometimes even hidden).

This extralegal argument cannot serve as a reference for the exercise of constitutionality control, much less as a justification for recognizing the validity of a law that creates or modifies the legislation of a tax.

With the edition of the Code of Civil Procedure (CPC) of 2015, article 927, § 3, was introduced, which contains a wording similar to article 27 of Law No. 9,868/99, which authorizes the Supreme Court and other higher courts to modulate the effects of their decisions, provided that there is a modification of its case law or in trial of repetitive appeals. The justification for modulating the effects should be social interest and legal certainty.

The point of attention is the existence of an understanding with broad scope and whose modification may affect a significant number of legal relations. For this reason, the effects of the decision are allowed to be calibrated, with the establishment of a specific moment from which the interpretation conferred should be observed.

The possibility of changing the interpretation of legal provisions is the result of the very dynamics of the rule of law and reflects the changes, in various ways, that occur in society and influence the applicators of law.

The search for legal certainty requires that acts consolidated and concluded in the past in line with the prevailing orientation at that moment must be protected and shielded against revision or reform based on supervenient interpretation.

Due to a scenario marked by changes in interpretation, legal certainty as a value to be achieved presupposes the establishment of beacons and criteria that protect the administered who act in moderation, following guidelines provided by the Administration itself or even precedents emanating from the Judiciary.

It cannot be accepted that a predominant interpretation in a given period is used as a basis for the revision and/or reform of an act performed many years earlier, when the orientation was different. This is the concept of legal certainty which we advocate and on the basis of which we believe that the modulation of the effects of decisions amending dominant case law should be based.

The consequence of the modification of the dominant case-law is seen, by positive law itself, as a factor authorising the limitation of its effects. And what would that be? The disregard of many legal acts implemented under the then dominant orientation, forcing the return to the previous situation. In the case of the tax liability, it is the possibility of repaying amounts paid improperly or even the collection of amounts not paid in due course.

By authorising the effects of the decision to be limited and avoided the consequences of the undoing of acts carried out in accordance with the guidance of the higher courts, law recognises that, exceptionally, extralegal factors may be invoked as the basis for a given decision.

The alternative requirement to allow the modulation of the effects of decisions is the social interest. Once again, the consequences of the decision for society may be used as a reason for limiting the effects of the judicial pronouncement.

The argument often invoked as the basis for requests for limitation of the effects of a decision that recognizes the unconstitutionality of the device that creates or modifies the rule of a particular tax – harmful impact on the public coffers – cannot be accepted, if solely taken. Social interest is not confused with the interest of the tax administration.

The assumptions that lead to consider possible effects of the decision in society as an extralegal justification to limit the effects of the decision are put by law and should be observed.

As this is an exception accepted by law, it is essential that the modulation of the effects of judicial decision-making on the basis of extralegal grounds be adopted sparingly. It should only occur when the authorizer requirements are present.