He tried to extradite General Pinochet, ordered the arrest of Osama bin Laden, put notorious members of the Argentinian junta, such as Adolfo Scilingo, behind bars and investigated the mass executions of nearly 150,000 Spanish Republicans under General Franco. But yesterday, in the first of three cases, Spain's crusading high court judge, Baltasar Garzon, went on trial himself.
Garzon, who is viewed by many as Spain's most courageous legal watchdog and the scourge of bent politicians and drug warlords the world over, faces up to a 17-year suspension from his job in the initial case alone.
The hearing, into whether the judge abused his powers, will investigate claims he ordered illegal police recordings of conversations between suspects in a massive corruption case in Valencia, involving high-profile figures from Prime Minister Mariano Rajoy's Partido Popular Party.
Yesterday, dozens of Garzon's supporters, including Communist Party deputy Gaspar Llamazares, stood outside a packed courtroom in central Madrid and cheered the judge as he picked his way through the throngs of journalists.
"Fine, just fine," he answered, when asked how he was feeling.
Llamazares told reporters the 56-year-old judge was the victim of a political witch-hunt for his human rights work, which in Spain has concentrated on the mass murders of Republicans during the Civil War and the early part of Francisco Franco's dictatorship.
Garzon was suspended from his duties in May 2010, and even if he is cleared in this case - an outcome widely believed to be unlikely - next week a second, more controversial, case means he will be back in court for alleged professional misconduct during his Civil War investigations.
And a third trial, as yet unscheduled, will see him charged with accepting illicit payments from Spain's biggest bank, Santander.
Now working as an adviser at the International Criminal Court in The Hague, Garzon entered the Madrid courtroom yesterday in apparent good spirits and wearing his judge's robes in for what could be the last time.
He came to prominence on the back of Spain's principle of universal justice - which allows suspects in international cases to be tried in Spain, even if there is no immediate connection to the country - but was the first judge to exploit it fully when he ordered the arrest of Chile's former dictator, General Augusto Pinochet, in Britain in 1998.
Seeking justice the targets
General Augusto Pinochet
The spotlight first shone on Judge Baltasar Garzon in 1998 when he requested the arrest of Pinochet in London. Spain tried to extradite Pinochet for crimes committed during the coup he led as head of the Chilean military in 1973 (before he installed himself as President ). The President he toppled was killed along with more than 3000 supporters. Thousands more disappeared. Pinochet was detained for 18 months before British Home Secretary Jack Straw deemed him too unwell to stand trial and he was allowed to return to Chile.
Garzon was also behind the trial of the ex-navy officer Adolfo Scilingo for crimes against humanity committed during Argentina's "Dirty War" (1976-1983). Scilingo was found to have been on an aircraft from which 30 people were thrown, among other atrocities. He was sentenced to 640 years in prison in April 2005.
18 al-Qaeda members
In 2003, Garzon indicted a list of suspected terrorists, including Osama bin Laden. Eighteen were convicted and received long prison sentences.
In 1998, Garzon was behind the trial of Spain's Interior Minister Jose Barrionuevo and his security chief. They were jailed for involvement in anti-terror "death-squads", and for financing the kidnap of alleged Eta activist Segundo Marey. They were pardoned in 2001.