A court struck down anti-terrorism laws Friday that had been used to quash rebel movements in the 1990s, in a decision that could bring new trials for many people imprisoned on terrorism charges.
The Constitutional Tribunal's ruling came after an examination of four decrees approved by former President Alberto Fujimori.
The measures, including harsh prison sentences and the use of hooded military tribunals, were initially popular with many Peruvians who had grown tired of more than a decade of bloody rebel insurgencies. But they drew international criticism for their secrecy and lack of due process.
Among other findings, the court declared the use of military tribunals to try civilians unconstitutional. The move could open the way for civilian trials for about 900 people convicted in military courts, including Abimael Guzman, founder of the leftist Shining Path guerrilla group.
Court President Javier Alva said the ruling would not set rebels free or disqualify evidence.
The court also said life sentences for rebels convicted of terrorism are an unconstitutionally excessive punishment.
Fujimori criticized the rulings, which had been expected. He has been living in Japan since he fled Peru amid a corruption scandal that toppled his decade-long regime in 2000.
"It seems the current government has forgotten that hell, has forgotten the 30,000 people killed by barbaric terrorism," he said.
By the early 1990s, guerrillas had driven the Peruvian government virtually to its knees with a campaign of bombings, assassinations and other violence.