Fundamental rights are the supporting basis of democratic states that follow the rule of law. The appliance of these rights does not happen in an equal way in all societies that proclaim them, nor to all the people within these societies. The divide between civil and political rights on one hand, and economic, social, cultural, and environmental rights on the other is defended by the very own essence of these rights, and by the principles of the international normative that considers them indivisible, interdependent, and inter-related. Because of that, I proposed that the interconnection between fundamental rights be rethought through a theoretical substrate capable of making these principles clearer and operative and taking into consideration the inequality in the enjoyment of these rights and the root of this unequal division. With that in mind, it unites debates about the capability theory presented by Amartya Sen and Marta Nussbaum to the social tensions identified by Nancy Fraser. Moreover, within the several arenas through which it is possible to search for the effectiveness of these rights I tried to focus on the contribution made by the justice system to this process. For that, I needed to highlight that the justice system does not act alone, it is part of a network that I named Fundamental Rights Assurance System (SGDF), which is formed through the articulation and integration of state functions (public administration, legislative offices, and judiciary offices) in the three federative levels, with organized civil society and citizens in an individual manner or through groups of interest. The SGDF should act through three paths, in favor of the effectiveness of fundamental rights: promotion, defense, and control. Although I have emphasized that the SGDF structures itself materially and not through individuals, I highlighted that the epistemological frame of this thesis focuses on the groups historically denied rights in these three societies due to the fact that they are not only the neediest in the enjoyment of rights, but also in the access to justice. The three axes are interconnected, but the justice system has the main role in the defense field. In such area I have analyzed the role of Constitutional Courts in India, Brazil, and South Africa in the appliance of these rights for those people with a significant historical deficit of access to fundamental rights. The data coming from India and South Africa were used with the intent of obtaining a more inspired insight on the Brazilian context. The intent was not to compare these countries, but value the exchange of experiences among countries in the south with similar issues to face. The conclusion that the access to the Supreme Federal Court by underprivileged groups remains with a large deficit, even with the huge effort the Court makes in judging a large number of cases, lead to the outline of two proposals with clear inspiration in the South African and Indian context: the direct access to a Constitutional Court and the creation a new way to decide about social rights.