The longest-serving judge in Louisiana fired back Thursday at a legal challenge over whether he can hold onto the title for another six-year term.

Orleans Parish Criminal District Court Judge Frank Marullo argued in a legal brief that he should remain on the ballot, dismissing a challenge by three voters who filed a lawsuit Monday arguing that, at 74, he should be barred from running again.

A hearing set for Friday in front of Orleans Parish Civil District Judge Kern Reese sets up as a legal bout pitting Marullo, a former New Orleans Athletic Club boxer, against Father Time and supporters of an opponent four decades his junior.

Marullo faces four opponents in the race for the Section D seat he has held for 40 years, but many political watchers think he’s a clear favorite if he can win in court.

The lawsuit, filed by backers of former Orleans Parish prosecutor Graham Bosworth, claims that by any measure, Marullo is too old to run again.

The state constitution, which went into effect 106 days after Marullo first took office, sets an age limit of 70 for all judges in the state, though it allows them to serve out their term of office if they reach that age during their term.

The old constitution, in place at the time Marullo first took office, set a hard, 75-year age limit, forcing judges to retire upon reaching that age.

Marullo, who turns 75 on Dec. 31, argued in an 11-page brief filed Thursday that he is entitled to the best of both worlds: the 75-year limit under the 1921 constitution and the permission to finish a term that was added to the current constitution in 2003.

Marullo says his New Year’s Eve birth date doesn’t matter because he would start his new term in office before the first of the year, should he win re-election. What’s important, he argues, is that he qualified last week to run for office at a spry 74.

A frequent thorn in the side of Orleans Parish District Attorney Leon Cannizzaro, Marullo has said he intends to serve out his term if he wins.

Marullo also claims that a constitutional amendment on the Nov. 4 ballot that would abolish the age limit for judges would make his opponents’ arguments moot.

In their lawsuit, voters Marian Cunningham and Lisa and Robert Amoss take a different tack, claiming that Marullo is ineligible to run under either constitution.

Marullo is the only active judge in the state to whom the 1921 constitution might apply, and he cites legal precedents in favor of letting people run when there’s doubt over their eligibility.

As recently as last year, Marullo seemed inclined to leave office, if only because he wasn’t sure his candidacy would pass legal muster. Bosworth, 35, said he initially sought Marullo’s blessing and that the judge told him he was hanging up his robe.

But Marullo had a change of heart.

“I just don’t know what I would do with myself if I wasn’t there” at court, he said recently.

Appointed by then-Gov. Edwin Edwards, Marullo faces opposition on the ballot from Bosworth, former prosecutor Brigid Collins, former Magistrate Commissioner Rudy Gorrell and attorney Marie Williams.

At least some of the challengers are likely to drop out if Marullo’s candidacy is upheld.

Follow John Simerman on Twitter, @johnsimerman.