The Western Hemisphere's top human rights court says that Brazil must throw out an amnesty granted for crimes committed during its two decades of military dictatorship.
The ruling issued Tuesday by the Inter-American Court of Human Rights held the Brazilian government responsible for the forced disappearance of 62 alleged members of the Araguaia guerrilla movement-- a small armed band of communists crushed by military operations between 1972 and 1975.
Only about 20 members of the group survived. One of them is Jose Genoino, who later headed the ruling Workers' Party of President Luiz Inacio Lula da Silva and President-elect Dilma Rousseff, herself a survivor of torture in the dictatorship's prisons.
Brazil's amnesty law, passed in 1979, barred prosecution of both government agents and leftist militants who committed politically related crimes during the 1964-1985 military regime. The law was recently upheld by Brazil's supreme court.
The Costa Rica-based court found the law incompatible with Brazil's commitments under the American Convention on Human Rights.
The head of the government's National Human Rights Secretariat, Paulo Vannuchi, said in a press conference Wednesday that authorities understand the ruling must be obeyed.
The country is also taking other steps to clarify what happened under military rule, Vannuchi said, noting that Congress is considering a bill to create a truth commission.
The court found the amnesty law "impedes the investigation and punishment of serious violations of human rights," and said it "cannot continue to be a hurdle to the investigation" of the fate of the suspected Araguaia guerrillas.
The Brazilian government must investigate, prosecute and punish the perpetrators involved in the Araguaia case, find and identify the bodies of the disappeared, and make amends to their surviving relatives, the court concluded.
It also said authorities should release archived information about Araguaia, and information on other human rights violations that took place during the military regime.
"I hope this ruling can be a tool for change," said Beatriz Affonso, director of the independent Center for Justice and International Law, which advocates prosecution of military human rights violators. "The Brazilian state has a duty to fulfill (as a signatory of the American Convention on Human Rights.)"
Earlier this week President Luiz Inacio Lula da Silva asked the Defense Minister, Nelson Jobim, for an update on the search for bodies of those who disappeared in Araguaia. The army has not revealed their location.
Jobim has not commented to the media about the court's decision.