Prosecutions under the Torture Convention are rare. But in October 2008 a court in Miami convicted Chuckie Taylor, son of the former Liberian President Charles Taylor, and sentenced him to 97 years in prison for torture committed in Liberia.
The Bush administration praised the verdict as a great day for justice. Charles Taylor is currently in the Hague on trial for war crimes.
Judge Garzon's most famous target was Gen. Augusto Pinochet, the former dictator of Chile who was detained in 1998 under the judge's warrant while he was visiting London for medical treatment.
British authorities kept him under house arrest for two years before he was allowed to return home to Chile, because his lawyers said he was too ill and infirm to stand trial. He lived on for eight more years and died peacefully, without ever facing trial.
The case of the six Bush-era officials will almost certainly come up when President Obama meets Spanish Prime Minister Jose Luis Zapatero for a bilateral meeting during the Summit of G-20 leaders in London next week.