The former au pair, long since naturalised, is a judicial scourge of the great and not so good; the best known of the crusading magistrates who have transformed the moral climate of French politics and business in the past five years.
It was Eva Joly who helped to bring down Bernard Tapie, the doubtful businessman turned colourful politician; it is Eva Joly who is currently unravelling the odd financial arrangements of the former foreign minister Roland Dumas. Her life has been threatened scores of times; she rarely appears in public without dark glasses, which add, fetchingly, to her aura of menace.
Now the French establishment - or part of the establishment - is fighting back. Ms Joly, 55, a woman of legendary fierceness and short temper, is the target of four separate legal actions. All accuse her, in effect, of overstepping the considerable independent powers of the juge d'instruction or examining magistrate.
Napoleon, an expert on power, once said that the juge d'instruction was the "most powerful man in France". Ms Joly is generally recognised to be the most implacable of the present generation of investigating judges. Last year, to try to squeeze a confession from Mr Dumas's mistress, Ms Joly had her locked up for three months without charge.
The overall aim of the proliferating legal actions against the judge is clear: to force the French government, or judicial system, to remove her from her most high-profile cases, the investigation of the tentacular political-financial activities of the oil firm Elf in the 1980s and early 1990s, and the related bribery allegation against Mr Dumas. So far Ms Joly is standing firm. So is the French government. The justice minister, another formidable woman, Elisabeth Guigou, has rejected all pleas to sidetrack Ms Joly.
Matters came to a head this month when Ms Joly told a group of American and British journalists that "15 per cent of all the proceeds of crime" in France goes directly to defence lawyers. She also said that "money- laundering could not exist" without the connivance of the unscrupulous wing of the legal profession.
She explained later that she was merely quoting from official studies and a book published by another French magistrate. No matter. Organisations representing French lawyers exploded with (possibly synthetic) fury.
Ms Joly has already shaken the profession by leading a series of raids on the offices of lawyers that she suspected of abetting illegal activities or harbouring information (including the whereabouts of a high-profile fugitive in the Elf case). In one raid, personally conducted by Ms Joly, she ordered police to copy all the files on the office computers, ordered a secretary to empty out her handbag and even examined the contents of the children's computers in the adjoining apartment.
The judge faces two legal actions as a result of this raid, one following her comments on money-laundering lawyers and one by Mr Dumas, accusing her of being biased against him.
Ms Joly was a latecomer to the ranks of the judiciary. Having married her French boyfriend, now a doctor, and produced two children, she trained as an examining magistrate but took a series of less demanding legal jobs as her family grew up. She received her first magistrate's appointment in 1993.
She still speaks with a slight Norwegian accent and occasionally - it is cattily reported - makes grammatical errors, confusing the genders of some nouns. Her foreign background has undoubtedly contributed to the depth of feeling against her. One francophone African president - whose cosy dealings she was disturbing - subjected her to a curious form of anti-Scandinavian racism. Omar Bongo, the President of Gabon, wrote in his personal newspaper column that Judge Joly "smelled of cod".
It is a fact - seized upon by some wayward politicians as evidence of an anti-French conspiracy - that several of the best known examining magistrates have foreign names and backgrounds. Ms Joly's perpetual sidekick - tall and dark where she is short and blonde - is Juge Laurence Vichnievsky, of Russian-Jewish extraction. The two make an odd but effective couple: Ms Vichnievsky is said to be the soft, or softer, cop; Ms Joly is always the enforcer.
What does drive Juge Joly? Colleagues say she is inspired by a northern European distaste for the kind of anti-democratic insider dealing and cronyism which infested French politics up to the late 1980s. She regards herself not so much as slayer of giants as a crusader for the rights of little people.
The increasingly peremptory behaviour of Ms Joly and other investigating judges has led to fears that France might be exchanging one form of tyranny for another: moving from an unaccountable politico-bureaucratic elite to a judicial one. She rejected such charges in a rare TV interview last year. "The sense that judges are usurping parliament is due to one fact," she said. "People who have been used to explaining their misdeeds to no one find, abruptly, that they are being brought to public account."