International law, which main sources are agreements and international conventions, is increasingly present in internal affairs in such way that it is difficult to imagine an area of national law which has not been affected in some way by standards imposed by agreements. But how and to what extent international law will be applied internally will depend on the way in which States comply with their international obligations. Therefore, it is essential to know how States bestow domestic legal effect to their agreements. The theoretical question about the relationship between domestic law and international law is usually presented on the basis of dualistic (or pluralistic) and monistic theories, that can not, however, comprehensively cover all aspects of this relationship. The Constitution of the Federative Republic of Brazil recognizes, yet indirectly, international agreements as part of domestic law, but left important aspects related to its application without answers. Thus, the Brazilian judiciary has faced critical issues relating to the impact of agreements in domestic law, particularly regarding its duration, effects and hierarchical position. Despite the Brazilian judicial performance, legal uncertainties regarding the matter persist, which will be exposed in this article.