By Daniel Schweimler
BBC News, Buenos Aires
Argentina's Supreme Court has revoked a pardon granted to a former general accused of human rights abuses.
The ruling against Mr Riveros is seen as a test case
Santiago Omar Riveros is accused of more than 40 crimes against humanity which were committed during the military rule of 1976-1983.
The ruling opens the way for all of those accused of involvement in the "Dirty War", in which an estimated 30,000 people were killed, to be tried.
Mr Riveros was pardoned in 1989 by the then President Carlos Menem.
Hundreds of other military leaders and policemen were also pardoned at the same time.
They hoped to live the rest of their lives in peace but the survivors and the families of the victims of seven years of military rule, in which an estimated 30,000 people were kidnapped and killed, continued their fight for justice.
They found a strong ally in President Nestor Kirchner and, one by one, the pardons and amnesties granted in the early days of democratic rule have been overturned.
The ruling against Mr Riveros was a test case.
The decision means the door is now open for other military leaders, such as Jorge Videla and Emilio Eduardo Massera, to be tried.
They are old men now, but human rights activists believe justice must be done before Argentina can begin to put one of the darkest periods of its history behind it.