1964 marked the beginning of the Military Regime in Brazil. From that moment onwards, a series of restrictive measures on the liberty of citizens was implemented, including laws of exception and the proscription of political rights. But 20 years later, in 1985, the “transition into democracy” was launched. Starting in the 1990s, a discussion in favour of the opening of archives due to their importance and significance for human rights arose in many countries. Possibly influenced by these discussions, Brazil passed Law No. 8.159, known as the “Law of Archives” in 1991. From 2008, the Brazilian media began to use the term “transitional justice” more frequently, something which highlights the role of archival documents as a necessary source in the process of reconciliation. In 2011, Law No. 12.527, the Law of Access to Information, was passed. Besides determining that the State shall adopt a more open policy on information, this Law is also innovative in terms of its comprehensiveness, since it applies to organizations and entities of all three branches of government, at all levels of the Federation. This study shows that all legal instruments prior to the Law of Access to Information of 2011 tended toward secrecy and opacity. A table of laws and decrees relating to the archives in the 75 years from 1936 is included.