Napoleon Bonaparte defined the examining magistrate as "the most powerful man in France". No French examining magistrate is more powerful than Jean-Louis Bruguiere.
An anti-terrorist judge for more than 20 years, he played a major role bringing to justice the man known as Carlos the Jackal and Libyan officials convicted of blowing up airliners in the 1980s.
In recent years, Mr Bruguiere has rounded up hundreds of suspected militants at home, and earned a global reputation as a key player in the fight against al-Qaeda.
Bruguiere has tracked down terror suspects for two decades
But although his effectiveness is widely admired, his methods - illustrated by the recent clampdown on Iranian exiles - have been questioned by human rights groups.
Mr Bruguiere, who once carried a magnum pistol and is still sometimes nicknamed "the sheriff", has set his sights on Islamic militants for the past decade.
"He has been out in the forefront in the war on terrorism," says Walter Purdy, director of the Terrorism Research Center in Washington.
In the early 1990s the judge focused on what the French called the Afghan networks - Arab veterans of the 1980s war against the Soviets in Afghanistan.
Mr Bruguiere was particularly interested in Algerians who had returned to fight the military-backed government, and were now taking the war to France - a long-time ally of the Algiers regime.
Algerian "Afghans", supported by angry young immigrants in France's bleaker suburbs, carried out a number of attacks in 1994 and 1995 - including the hijacking of an Air France plane and the bombing of a Paris underground station.
Mr Bruguiere became an expert in a new breed of Islamic militants working in loosely-connected local cells around the world.
An anti-terrorist inspector calls
In the late 1990s he alerted foreign governments about their activities - with only limited success.
Canada, for instance, failed to act on the judge's warning about an Algerian asylum seeker living there, Ahmed Ressam.
In 1999 Ressam was arrested in the United States with a car full of explosives, and convicted of planning to blow up Los Angeles airport.
However since the 11 September attacks, security officials everywhere have been keen to tap Mr Bruguiere's knowledge of al-Qaeda.
"He has probably mentored quite a few individuals, giving them insights as to how those groups worked worldwide," Walter Purdy told BBC News Online.
Mr Bruguiere's international standing stems not just from his personality and drive, but also from the unique powers he wields.
Laws approved after a wave of bombings in Paris in 1986 created a group of specialist anti-terror judges - which he now heads.
Suspects can be held for four days, as opposed to two in other cases, before a formal investigation is launched.
People are indiscriminately arrested, often in violent conditions
Human rights lawyer
The legislation also created a new catch-all charge of "conspiracy in relation to terrorism", which has enabled judges the cast their nets wide.
"There is no doubt that [Mr Bruguiere] has used his powers to the full under the penal code," French terrorist expert Olivier Roy says.
The judge's habit of picking up van-loads of suspects in spectacular raids has made France the most hostile environment for militants in Europe.
But the "Bruguiere method" has been criticised by human rights advocates, who accuse the judge of running roughshod over defendants' rights.
"People are indiscriminately arrested, often in violent conditions," says Patrick Baudouin of the Paris-based International Federation of Human Rights Leagues.
The recent targeting of the Iranian People's Mujahideen - who are officially regarded as terrorists by the US and the European Union - is a case in point.
In June Mr Bruguiere ordered a series of raids near Paris, in which 1,200 officers arrested 160 alleged members of the organisation.
Some Iranians staged spectacular protests against the detentions
"Police turned up at six in the morning, and pulled them out of bed," says Mr Baudouin.
Most suspects were released - after spending up to four days in police stations and being subjected to questioning.
"Suspects are placed in a position of weakness compared to policemen who continually harass them," says Mr Baudouin, who represents three of the 17 who have been placed under judicial investigation.
Of these 17, 11 are in preventive detention - and could remain there for a long time.
French justice moves slowly, particularly in terror cases.
In the biggest case ever initiated by Mr Bruguiere, involving 138 people accused of aiding Algerian militants, defendants spent up to four years in preventive detention before their trial in 1998.
In the end 51 were cleared and many others were given suspended sentences.
Besides accusations of heavy-handedness and abuse of preventive detention, critics accuse Mr Bruguiere and his colleagues of not giving defendants a fair chance.
Examining judges are supposed to keep an open mind during their investigations, but according to Mr Baudouin, French anti-terror judges systematically side with the prosecution.
"They prepare extremely long, complicated questions, provide the answers themselves, and then ask - what do you say about this?" he says. "There is no real dialogue with suspects."
Such criticisms, however, are confined to France's small human rights community.
They are occasionally mentioned by left-leaning newspapers like Le Monde, but fail to have an impact with the population at large.
For the overwhelming majority of French people and politicians, Mr Bruguiere is a hero.
And in this post-11 September world, they feel that an erosion of civil liberties is a small price to pay for the sense of increased security that comes with having a powerful "sheriff" around.