Too old? The 92-year-old US judge handling Maduro case
But as one of the oldest US federal judges -- born in 1933 -- some are unsure he is best suited to preside over what could be a prolonged trial for Maduro on drug trafficking charges.
"The issue of age cannot be ignored," Shira Scheindlin, a former federal judge in New York, told AFP.
Still, she praised Hellerstein as a "very smart and savvy" courtroom operator.
His lengthy career includes overseeing the civil cases arising from Al-Qaeda's September 11, 2001 terror attacks on New York and Washington, often rejecting deals he saw as unfair to complainants.
Hellerstein has also tangled with Donald Trump, rejecting a request by the US president to have his New York hush money case moved to federal court.
And last year, he blocked the Trump administration from deporting alleged Venezuelan gang members without a court hearing.
"Hellerstein possesses a well-deserved reputation for seeking to do justice in every case and for being independent and fair-minded," said law professor Carl Tobias of the University of Richmond.
In a noteworthy 2015 ruling, Hellerstein ordered the US government to release a trove of photos depicting abuse of detainees in Iraq and Afghanistan.
He also presided over a trial last year in which a jury found French banking giant BNP Paribas's work in Sudan had helped prop up the regime of former ruler Omar al-Bashir, awarding $20.75 million in damages to three plaintiffs from Sudan.
Hellerstein has handled the sprawling drug trafficking case linked to Maduro for over a decade, which has already seen the conviction of Venezuela's former intelligence chief, Hugo Armando Carvajal.
Maduro's stunning arrest in January following a US raid on his compound in Venezuela has drawn public eyes to the case -- and the aging judge in charge.
According to The New York Times, Hellerstein was seen falling asleep during a trial last year and needed to be roused by his colleagues.
His attentiveness will be closely watched in the Maduro case, as tussling between the defense and prosecution has already threatened to draw out proceedings.
"This case may not go to trial for at least a year and maybe two years. By that time, he would be either 93 or 94," said Scheindlin.
"I have no doubt that he would be fit to try the case tomorrow. But the case will not be tried tomorrow," she added.
A graduate of Columbia University law school, he served as a lawyer in the US Army from 1957 to 1960 before entering private practice.
He was nominated by former president Bill Clinton in 1998 to be a district court judge for the Southern District of New York.
Maduro's next scheduled court appearance is Thursday, when he is due before the judge, along with his wife who has also pleaded not guilty.