The decision by a Chilean appeal court on Friday to strip former dictator Augusto Pinochet of his immunity, in order to face a new trial for human rights atrocities, was as unexpected as it was welcome. The astonishment was palpable, when lawyers, journalists, and relatives who were awaiting the start of a quite separate human rights hearing first heard the news. The white-haired judge, who had chaired the panel responsible for the decision, was greeted with applause as he walked past. As is from nowhere, demonstrators appeared outside the building. The hallways were filled with jubilant cheers.

General Pinochet, the brutal former dictator whose health problems have repeatedly enabled him to avoid standing trial for torture, murder and kidnapping during his 17-year rule, is expected to appeal. His lawyers may again plead his mental unfitness to stand trial, as they have already done on four previous occasions - once in London and three times in Chile. Friday's verdict will, however, remain a source of enduring comfort to his victims. It shows how tenacity in the cause of justice can still prevail against all the odds. It was a remarkable victory for Juan Guzmán, the judge who came close to convicting Pinochet for murder in 2001. The court's reasoning has not yet been published. According to some reports, however, a decisive factor was an interview Pinochet gave to a Miami television station last year. In that interview, he coolly announced that it was his victims who owed him an apology, and that he considered himself a "good angel."

The crimes Guzmán is investigating were part of "Operation Condor," a clandestine scheme by the military regimes of Chile, Argentina, Brazil, Uruguay, and Paraguay in the 1970s to kidnap and 'disappear' dissidents from each other's countries, or smuggle them back home for torture, interrogation and imprisonment. So far, no one has been held accountable for these crimes, which were planned carefully to cover the state's tracks. Argentine and Uruguayan perpetrators escaped under amnesty laws which were tailored to shield them for trial. But Chilean courts have repeatedly refused to apply the self-amnesty which Pinochet ordered in 1978, to draw a veil over his brutal crusade against the opponents of his regime.

Of more than 200 former officers now facing trials, 15 have received jail sentences, including Pinochet's former intelligence chief, Manuel Contreras. On the same day as the Pinochet decision was announced, the Supreme Court began hearing Contreras's appeal, which challenges the interpretation of the amnesty now current in the criminal courts and calls for the amnesty to be applied immediately.

Contreras faces a 15-year sentence for ordering the kidnapping of Miguel Angel Sandoval, a 26-year-old tailor who "disappeared" in 1975 after being held and tortured in the Villa Grimaldi, a notorious Santiago detention camp. Sandoval was one of 119 people who went missing after their arrest in Chile and were later falsely reported in the press to have been found dead in Argentina, a ruse concocted to cover up their secret execution. It was a good example of the modus operandi of Operation Condor.

If the Supreme Court approves an amnesty for Contreras and his comrades, Chile would be defying fundamental principles of international human rights law, including the principle that crimes against humanity are not subject to statutes of limitation and should not be amnestied. The United Nations Committee against Torture recently urged Chile to abolish the amnesty decree, noting that it "entrenched impunity for those responsible for torture, disappearances and other serious human rights violations during the military dictatorship."

The appeal court decision on Pinochet serves as a good reminder that an increasing number of judges now understand that justice can only be real if those who have committed the worst crimes are not allowed simply to walk free. We must hope that the judges of the Supreme Court, by striking out the amnesty for Contreras and others, will follow the appeal court's lead in this matter. The Pinochet and the Contreras decisions will have implications that go well beyond Chile's borders. In an age of international justice - including the International Criminal Court, whose work is just getting under way for crimes committed since the court's creation in 2002 - brutal rulers must accept that the era where they could expect to avoid accountability for all time is finally over.