Born in Orange, New Jersey, Mahoney received a Bachelor of Arts degree, magna cum laude, from St. Bonaventure University in 1952.
[2] In 1985, Mahoney represented the National Review and its editor, William F. Buckley Jr., during the magazine's $16 million libel suit against The Spotlight.
Marlin was the Conservative Party mayoral nominee in 1993, having been defeated by the then-liberal Republican Rudy Giuliani.
Mahoney was nominated by President Ronald Reagan on February 7, 1986, to the United States Court of Appeals for the Second Circuit, to a new seat created by 98 Stat.
He was confirmed by the United States Senate on March 27, 1986, and received commission on April 7, 1986.