On the 1990s, through a political reform, also when the cooperation between Brazil and OECD began, the model of market regulation agencies was adopted in Brazil. Influenced by USA administrative agencies, Brazilian agencies are rule-making empowered. Controversies concerning the boundaries of agencies’ rules are usual, considering the separation of powers and the Legislative function. There are no general standards in Brazil to guide the judge´s analysis on whether the agency act was under its legally stated competence or not. Therefore, Brazilian courts oscillate from unrestricted deference on the agencies’ regulation to its invalidation in specific cases. In 2018, it was stated by law that whenever an administrative rule is invalidated by the judge, he ought to explicit the consequences of such decision, which may discourage judicial activism on this issue. In this scenario, the debate is on the importance of establishing general standards for this kind of judgment.