The beginning of 20th Century was a moment of great transformations, amongst which the first impulse in institutionalize a field of knowledge of International Relations. A structural change that happened 30 years after the abolition of slavery in Brazil. Despite the fact of being unrelated historical phenomena in objective terms, I argue that the possibility of analyzing them in tandem widens the critique to the racist premises of liberalism, a powerful ideological motivator in both events. The vitality of critical studies in IR has helped denounce the premises upon which the discipline is grounded and the definition of what is within the scope of its interest. The disciplinary critique is reconstructed in the first section and, in the second, I present the marginalization inscribed in legal norms of late 19th and early 20th Century Brazil. The technique of developing conditions for the segregation of a sector of the population disguising it from full-citizens by granting conditional-citizenship to former enslaved people is a sophisticated use of liberalism. Such use not only presents in full the critique of structural racism developed by the critique to this political project, already advanced by IR scholars, it also presents another discussion that has yet ground to cover in the field: the unchallenged premise of homogeneity within political communities.