The court’s 20 judges voted 14-6 to revoke Pinochet’s shield from prosecution as a senator in the upper house of Chile’s Congress.
The decision was reached last week, but the court waited to reveal the ruling until it was written and signed by all the justices.
Despite the high court’s decision, Pinochet’s foes say a quick trial is unlikely given his age, his medical problems and his other legal privileges.
Putting Pinochet on trial “could take up to eight years,” said Eduardo Contreras, a communist anti-Pinochet lawyer.
Pinochet allegedly was involved in a “Death Caravan” that killed leftists after his forces ousted elected socialist president Salvador Allende in a bloody 1973 coup.
During his reign from 1973 to 1990, more than 3,000 people died or disappeared. But his supporters say he stopped Chile from turning into a Marxist state under Allende.