As previously reported, Tony Award winners Christopher Plummer (Cyrano, Barrymore) and Frank Langella (Seascape, Fortune's Fool, Frost/Nixon) will star in the film directed by Stephen Frears, which "details the legal fight between Ali and the U.S. government when the fighter became a conscientious objector to the Vietnam War." Also in the cast is Benjamin Walker (Bloody Bloody Andrew Jackson). The film features Plummer as Supreme Court judge John Marshall Harlan, Chalfant (Angels in America) as Ethel Harlan, Langella as Chief Justice Warren Burger, Glover ("Master Harold"…and the Boys) as Justice Thurgood Marshall, Levinson as Justice Potter Stewart, Begley Jr. as Justice Harry Blackmun, Balaban (The Inspector General) as an advocate for Vietnam veterans, Schreiber (Awake and Sing!) as Covert Becker and Walker as Kevin Kennedy.

According to Variety, the film will utilize actual footage of Ali and not cast an actor to play him.

Frank Doelger, Tracey Scoffield, Jonathan Cameron and Frears are the executive producers of the film, which features a screenplay by Shawn Slovo.