This dissertation s objective is to investigate the Ministério Público da União s trajectory alongside the Justiça do Trabalho in the formation of citizenship within the sphere of labour at Brazil s very first democratic experience and, therefore, it is of interest to follow its developments during the broadened year of 1963. Our charge is to understand how this institution, conceived at the imago of Brazilian corporativism, acted vis-à-vis the urban proletarian movements which sought not only maintaining and actualizing the judicial labour order, but primarily conquering novel rights, elevating welfare and social justice standards. We have presupposed a new type of Legal process destined to theoretically break the individual s paradigm of abstraction, a collective process capable of agglutinating several voices and give them meaning within discussions, negotiations and decisions happening in an extremely specific arena: the Justiça do Trabalho, which, renovated, became one of the republican powers. We seek to understand the social actors experiences at the handling of these structures springing from singularities, searching for the answer on how a branch of the Ministério Público crafted during the Vargas Era would hear those voices and give them meaning. A Ministério Público capable of exercising swift vigilance in the name of the Executive Power inside tribunals, either paving the way to a consolidation of decisions or acting with certain independence along the workers plight for new rights through normative power.