In a 9-8 vote, Chile's highest court on Thursday lifted Pinochet's immunity, clearing the way for him to face criminal charges over the killings of thousands of political opponents during his 1973-1990 rule.
Relatives of 3000 political opponents who died during the dictatorship argue that Pinochet, 88, bears responsibility for their family members, many of whom disappeared while in custody and are presumed to have died.
Thursday's ruling allows Pinochet to stand trial for his part in Operation Condor, a collaborative effort among the 1970s and 1980s dictatorships in Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay, who killed opponents to their regimes and dumped bodies in each others' countries.
"For us, it's incredibly important that they have ruled to lift Augusto Pinochet's immunity. There could be no other ruling," said Lorena Pizarro, president of a group of families of the detained and disappeared (AFDD).
"This is a historic day, because it opens a window for us to get justice for all of the human rights violations," Pizarro, whose group represents thousands of families, said.
"We're very happy with the ruling. The country is now more democratic than it was yesterday," said Eduardo Contreras, one of the lawyers who is pursuing Pinochet for alleged rights violations.
Pinochet's supporters, however, rallied around the ex general and said he remains unwell.
"We profoundly disagree and are surprised" at the ruling, retired general Guillermo Garin, a spokesman for Pinochet, said.
Garin said nothing had changed since previous legal challenges against Pinochet were blocked on health grounds. Pinochet's lawyers claim he suffers from a mild dementia that prevents him from testifying.