Benjamin Lawsky, the New York regulator who has rocked French bank BNP Paribas with the threat of a $10 billion fine, has a record making the world's largest banks pay dearly for misdoings.
The former prosecutor is tough and ambitious, and that leaves him unpopular on Wall Street, where he is seen as an out-of-control cowboy.
But for Americans who see big banks as behind the deep economic woes of the past six years, Lawsky is a hero.
Lawsky, together with the Justice Department, is negotiating a likely record fine for BNP over allegations it actively moved money for countries like Sudan and Iran through the US banking system in violations of American sanctions on them.
According to reports, the US wants BNP to pay $10 billion to close the case, to admit guilt, and possibly see its crucial New York banking license suspended.
The case has become a diplomatic issue, with French President Francois Hollande taking up the matter with US leader Barack Obama.
On Tuesday, French Foreign Minister Laurent Fabius said the dispute "raises a very, very big problem" and warned it could impact ongoing talks on US-European Union transatlantic free trade treaty.
Lawsky though is hardly one to bow under pressure. As head of New York State's Department of Financial Services since 2011, he can extract fines and grant or remove banking privileges in the world's leading financial center.
Dark-haired, always crisply shaven to a cold elegance, the 44-year-old has taken the lead in going after huge, powerful banks.
His first big impact was threatening to pull the New York banking license of British Bank Standard Chartered in August 2012 for violating US sanctions on Iran, moving while federal investigators were still working their own case.
In the past, state regulators would normally follow the lead of the federal government in such cases.
A dozen days later, Standard Chartered agreed to a deal: it would pay New York a $340 million fine but get to keep the license.
That gave birth to Lawsky's reputation as a tough and courageous defender of the public interest.
Two years later, with a handful of prominent scalps under his belt, he now has his sights on BNP, the largest French bank, with 185,000 employees and 39 billion euros ($53 billion) in revenues last year.
"He does not follow the playbook," said one colleague, unwilling to speak on the record given the outstanding case.
Another emphasized that Lawsky represents New York state, not the country: "He won't take in account what the French president has to say. He will go the full distance."
Michael Greenberger, a former regulator with the Commodity Futures Trading Commission and now professor at the University of Maryland law school, called Lawsky fearless.
"For Main Street, these banks have committed terrible crimes that they deserve to be punished for. Mr Lawsky is just doing that."
- Political ambitions? -
Born in California and a law graduate of New York's Columbia University, Lawsky began his career as a prosecutor in Manhattan, drawing the notice of prominent politicians.
In 2011, New York Governor Andrew Cuomo, with his own reputation for fighting corruption, tapped Lawsky to head of the newly created Department of Financial Services.
That gave him huge power over some 4,400 financial institutions based in the state, including nearly all of the world's largest banks.
After Standard Chartered, there were Bank of Tokyo-Mitsubishi UFJ, accountancy Deloitte, and Credit Suisse, among others, who paid dearly under his enforcement efforts.
Lawsky is unapologetic for his aggressiveness, and for not waiting for Washington's regulators and prosecutors to act. His move arguably made the federal enforcers less timid with the banks.
"We shook things up with Standard Chartered," he said in a 2013 speech.
"A dose of healthy competition among regulators is helpful and necessary to safeguarding the stability of our nation's financial system."
In a state where tough prosecutors are expected to climb the political ladder, some see Lawsky as having his own ambitions, possibly even to follow Cuomo one day as governor.
"His success would lay the ground for his political career," said Greenberger.