Abstract
This article analyzes the amicus curiae institute as an instrument for democratizing the judicial decision-making process within the scope of Brazilian concentrated constitutional review. The research investigates the historical evolution of the institute and its importance for the democratic legitimacy of the Federal Supreme Court decisions, questioning the existence of valid reasons for not requesting technical input from the Friend of the Court in concentrated constitutional review actions. The study, based on bibliographic and documentary research, examines relevant legislation and STF jurisprudence on the matter. The analysis reveals that, although the Judiciary is not legitimized by popular vote, the amicus curiae enables qualified social participation in judicial decisions, contributing to the improvement of decisions through specialized technical knowledge. It is concluded that the institute represents more than a mere judicial assistant, constituting a true mechanism for democratizing the constitutional process, whose use should be encouraged to ensure greater pluralism and democratic legitimacy in constitutional review.