Moriarty is also known for his roles in films such as Bang the Drum Slowly, Who'll Stop the Rain, Q: The Winged Serpent, The Stuff, Pale Rider, Troll, Courage Under Fire, and Shiloh.
[7] In 1973, Moriarty was cast as the egocentric baseball player Henry Wiggen in Bang the Drum Slowly opposite Robert De Niro as a slow-witted, terminally ill catcher.
Coincidentally, the film also featured Sam Waterston, who later replaced Moriarty as the Executive Assistant District Attorney on Law & Order.
Moriarty's role in The Glass Menagerie (as Jim, the Gentleman Caller; Waterston played the son Tom) won him an Emmy Award for Best Supporting Actor.
He left the show in 1994, alleging that his departure was a result of his threatening a lawsuit against then-Attorney General Janet Reno, who had cited Law & Order as offensively violent.
Moriarty criticized Reno's comment and claimed that she wanted to censor not only shows such as Law & Order, but also such fare as Murder, She Wrote.
Moriarty published a full-page advertisement in a Hollywood trade magazine calling upon fellow artists to stand up with him against attempts to censor TV show content.
The February 7, 2018, episode of Law & Order: Special Victims Unit shows Sam Waterston's character, Jack McCoy, delivering a eulogy at Stone's funeral.
Law & Order producers claim they were forced to remove Moriarty from the series because of "erratic behavior", an example of which reportedly happened during the filming of the episode "Breeder", when, according to the episode's director Arthur Forney, Moriarty began muttering to himself with a vacant look in his eyes, was unable to deliver his lines with a straight face, and had to be taken to a doctor.
[11] Moriarty acted in The Last Detail, Courage Under Fire, Along Came a Spider, Shiloh, Emily of New Moon, and James Dean, for which he won his third Emmy.
[13] Moriarty announced his intention to run for the presidency in 2008 in an interview in the November 2005 issue of Northwest Jazz Profile, but he never formally declared his candidacy.