He indicted late Chilean dictator Augusto Pinochet on genocide charges and became an instant hero to many around the world. A decade later he launched a similar crimes-against-humanity probe over atrocities by the right-wing victors of Spain's Civil War.
Now Judge Baltasar Garzon is finding himself in the dock.
On Tuesday, Garzon goes on trial for allegedly ordering illegal jailhouse wiretaps in a domestic corruption probe. A week later he appears in court to face charges he overstepped his authority in the Civil War case.
Supporters say he's the victim of a witchhunt by courthouse colleagues jealous of his fame and of arch-conservatives angered by his attempt to revisit Spain's war-time past.
Whatever the motivations, Spain's once high-flying but now-suspended super sleuth may be about to crash and burn definitively.
Garzon doesn't face jail time if convicted in either trial. But he can be removed from the bench for up to 20 years, which at his age _ 56 _ would in effect end his career as an investigating magistrate at the National Court.
The judge _ who also charged Osama bin Laden and probed abuses at the United States' Guantanamo Bay prison for terror suspects _ is separately under investigation over his dealings with a big Spanish bank.
Garzon's lawyer says the precedent set by the trials, plus the probe which could lead to a third trial, will make it virtually impossible for Garzon to take up his post again even if he is acquitted in all three cases.
"Judge Garzon is facing the perfect storm," said the attorney, Gonzalo Martinez-Fresneda.
New York-based Human Rights Watch said the fact that Garzon was even charged for probing killings and forced disappearances by supporters of Gen. Francisco Franco during and after the 1936-39 war is an outrage.
The group's spokesman, Reed Brody, said it is already discouraging judges in other countries from applying the principles of law he championed.
Both sides in the Spanish war _ the Republican side and Franco's rebel right-wing forces _ committed atrocities. But they were addressed by a post-Franco-era amnesty approved by Parliament. Republican atrocities against pro-Franco civilians had already been thoroughly documented by the regime.
The specific charge against Garzon is that he knowingly overstepped the bounds of his jurisdiction with his unprecedented albeit abortive probe of crimes committed by the Franco side.
Garzon, a workaholic from a modest background in Spain's olive-growing south, certainly never expected to find himself in court as a criminal suspect.
Rights advocates in Spain and abroad adore him for his pioneering cross-border justice cases, which apply the principle of universal jurisdiction _ the idea that some crimes are so heinous they can be prosecuted anywhere, not just in the country where they are alleged to have been committed.
Since Garzon had Pinochet arrested in London in 1998 in an ultimately failed bid to put him on trial in Madrid, Garzon and colleagues at the National Court have issued indictments and arrest warrants over crimes in such far-flung places as Tibet and Rwanda.
The effect here in Spain has been largely symbolic. There's been only one conviction _ that of an Argentine 'dirty war' suspect who came to Spain voluntarily to testify and ended up charged and convicted in 2005. And there has been one extradition.
But the arrest of Pinochet inspired victims of abuses, especially in Latin American countries like Argentina, Chile and Guatemala, to challenge and win the repeal of laws giving amnesty to perpetrators of atrocities committed by military juntas, said Brody.
"Garzon changed the world," he said.
Spain's decision to put Garzon on trial before the Supreme Court, he added, "leaves Spain open to the charge of double standards: they are willing to work for justice in so many other countries and yet at home they have problems with a judge who seeks justice."
The second trial begins Jan. 24 with a session due to focus on procedural issues. It picks up again a week later, with Garzon expected to testify just that day. His lawyer says the proceedings will probably take a month altogether, with a verdict possibly coming in late March or April.
Garzon is arguably Spain's most polarizing figure.
Even as he became the darling of human rights advocates, he's made many enemies at home. Conservatives deride him as a limelight addict more interested in fame and front-page photos than justice and doing things by the book. They say his attempt to probe the war atrocities was unnecessary digging at old wounds best left alone.
However, even many Spanish Socialists hold a grudge against Garzon over his indictment of government officials over state-financed death squads that targeted the Basque separatist group ETA in the 1980s.
Jose Antonio Martin Pallin, a judge emeritus at the Supreme Court, said there are many people in Spain who want a piece of Garzon _ and his indictment in 2010 over the Civil War probe opened up the floodgates.
Among other things, he said, that gush stems from envy among judges who are used to discretion and modest salaries and disliked Garzon's glitzy lifestyle of jetting around the world to give well-paid lectures on human rights and attracting gaggles of reporters wherever he went.
The first indictment of Garzon meant "hunting season is now open," Martin Pallin said. He described fellow judges' thinking as "this man is going to get it now, for all his enjoyment, for his speaking fees."
Before dropping the Civil War probe in a dispute over jurisdiction _ it began and ended in 2008 _ Garzon declared he had the right to probe what he estimated were 100,000 killings and forced disappearances of people at the hands of Franco supporters and the regime.
Garzon called this a systematic drive to crush opponents and thus a crime against a humanity. His resolutions essentially amounted to an indictment of the Franco regime itself.
After Franco died in 1975 and Spain moved toward democracy while trying to put behind it a ruinous chapter of the past, Parliament in 1977 passed an amnesty for Civil War crimes.
Garzon did not challenge that law. Rather, he said that under the body of international jurisprudence that has accumulated since then, forced disappearances cannot be covered by the 1977 legislation. He argued that since no bodies have been found in cases of missing persons, the crimes are still ongoing.
Martin Pallin agreed that even if acquitted, Garzon would be so tainted as to be finished at the National Court.
"He would probably have to make a sort of symbolic return. Return, and then leave again," he said.