The path is now clear to establish his share of responsibility in Operation Condor, the strategy by which South American de facto military regimes coordinated the repression of political opponents in the 1970s and 1980s.
The nine-to-eight Supreme Court decision was received with joy by the families of victims of the dictatorship, while the centre-left coalition government took a cautious stance.
The followers of Pinochet criticised the ruling, and predicted that the trial would not prosper.
"This is a historic day, because this ruling opens a window of opportunity for us to try all of the human rights violators," said Lorena Pizarro, president of the Group of Families of the Detained-Disappeared (AFDD).
Pizarro led a group of around 100 AFDD members and other human rights activists holding a vigil outside the court building, who broke out in shouts of joy when the Supreme Court secretary announced the decision.
Pinochet, 88, enjoys special immunity from prosecution under a "statute on ex-presidents" that was passed to protect the former dictator when he stepped down as life senator in 2001.
The former army chief had already been stripped of immunity in 2000 on the request of Judge Juan Guzmán, who was investigating 57 homicides and 18 "kidnappings" (actually forced disappearances) blamed on the "caravan of death", a special military mission that travelled around the country in October 1973 eliminating key political prisoners.
Pinochet had seized power shortly before that, in a bloody Sep. 11, 1973 coup d'etat that overthrew the democratically elected government of socialist President Salvador Allende.
But before Guzmán was able to hand down a verdict in the case involving the "caravan of death", the Supreme Court ruled on Jul. 1, 2001 that the former dictator was mentally unfit to stand trial, based on controversial exams that found he was suffering from mild dementia.
The same argument, combined with humanitarian reasons, had been cited by the British government to release him in March 2000. Pinochet had been under house arrest in London since Oct. 16, 1998, after he was arrested there on the basis of an international warrant issued by Spanish Judge Baltasar Garzón.
Since 2001, the Chilean courts have rejected two other requests for stripping Pinochet of immunity.
But Guzmán, who is now investigating a case brought by families of victims of Operation Condor, presented a new request this year, which was approved by the Santiago appeals court on May 28.
According to documents from that era, Operation Condor first emerged in 1975 on the initiative of then-colonel Manuel Contreras, director of the Dirección de Investigaciones Nacional (DINA), the dictatorship's secret police, which answered directly to Pinochet.
Through that plan, the secret police of the Southern Cone dictatorships coordinated their activities, making it possible to pursue, kidnap, kill and "disappear" opponents of the de facto regimes ruling Argentina, Brazil, Chile, Paraguay and Uruguay at the time.
Over the past year, Pinochet himself has provided elements contradicting claims that he was going senile.
The first was a lengthy interview he gave in late 2003 on a Miami TV station, in which he argued his innocence, denied having violated human rights, and described himself as a good man persecuted by the left for defeating communism. The interview played a key role in the May 28 ruling issued by the appeals court.
In July, the former dictator once again gave signs of lucidity and mental clarity when he was seen buying books along one of Santiago's busiest streets.
That occurred on the eve of the release of a report by a U.S. Senate committee that detected secret accounts belonging to Pinochet in the Washington-based Riggs Bank, which may contain around eight million dollars.
Facing questions now not only as a human rights violator, but also for corruption and illicit enrichment, the former dictator will go to a new trial that could shed light on the obscure chapter of South American history involving Operation Condor.
José Miguel Vivanco, executive director of the Americas Division of Human Rights Watch, said in a statement Thursday that the Supreme Court decision "is an important step toward holding Pinochet accountable for the abuses his regime committed. He can no longer use his status as a former head of state to shield himself from justice."
The human rights organisation Amnesty International also applauded the Supreme Court ruling, stating in a communique that Chile had made a great stride towards justice.
Amnesty's Neil Durkin said "We absolutely welcome this decision. It is long overdue as far as we are concerned. This is the first real opportunity to ensure that those who commit human rights abuses" are brought to justice.
The London-based rights group also said the Supreme Court decision is an important step towards restoring confidence in the Chilean judiciary after a two-decade wait.
But Pinochet's supporters complained about the verdict.
Parliamentary Deputy Patricio Melero, secretary-general of the Independent Democratic Union, a right-wing party closely identified with the former dictator, said the ruling was "contradictory and useless," since "it is obvious that these kind of problems (senility) only get worse in time, not better."
Because of the Supreme Court ruling, Judge Guzmán can now restart his investigation into Pinochet's responsibility with regards to Operation Condor. But it is not yet clear whether he will first move to clarify the state of the elderly retired general's health.
Two of the nine judges who voted in favour of stripping the ex-dictator of immunity said Guzmán must first order new medical exams for Pinochet, before taking any other steps.
© 2004 IPS