This paper discusses the importance of conventionality control for the unity of the Brazilian legal system and for the validity of internal normative acts set in accordance with human rights. Unfortunately, Amnesty Law no. 6683/79 has served as an obstacle for the investigation of past human rights atrocities in Brazil’s military dictatorship past and the identification and punishment of those responsible for it. This paper concludes that this law is incompatible with the American Convention on Human Rights, which is an important part of the Brazilian legal system. Moreover, this law is not immune to the double control of the validity of state normative acts, because it was declared inconvenient in a ruling of the Inter-American Court of Human Rights in the Gomes Lund case, and should therefore be declared invalid by Brazilian courts.