Trabalho de Conclusão de Curso apresentado ao Departamento Acadêmico de Direito da Fundação Universidade Federal de Rondônia, campus Professor Francisco Gonçalves Quiles, para obtenção do título de Bacharel em Direito. Orientador: Prof. Esp. Silvério Santos OliveiraThis present paper is meant for studying the character of amicus curiae as carrier agent of useful information for the optimization of the judgment in constitutionality’s control consummated for Supreme Court of Judicature. It searches the advantage and repercussion of its participation in a process marked for objectivity characteristics. For in such a way, it uses as methodology the deductive method, the process of bibliography comparison with the exposition of thought from variously teachers and its admittance at Supreme Court. At a first moment, consideration are made as respect the Latin expression and exposed succinctly the reason why translate in the vernacular expression is not used, as well as notice of the starting of the institute in other juridical systems and the doctrinal discussion as much as the true origin of amicus curiae. After this, it studies the juridical nature of amicus, analyses the concept of component and third part, as well as the modalities of third intervention in civil process and other process components, it has seen that the Brazilian doctrine is not unison for the question of juridical nature of amicus curiae. The third chapter presents one general theory of amicus curiae, it has starting of the beginning in Brazilian Law, it is passing by the correlates principles, the admittance requirements, the legitimated components, the process for intervention, the terms, the possibility oral sustentation and the plurality of amicus curiae. Subsequently, it analyses the amicus curiae in the scope of the abstract control of constitutionality with eminence for the general characteristics of the abstract control of constitutionality, the necessary action, the proceeding opening of constitutionality’s control and, finally, as legitimation factor, democratization and improvement of the judicial decision.