The script for The Defiant Ones was brought to Kramer's company by two relative unknowns - Harold Jacob Smith and Nathan E. Douglas. Smith had one previous film to his credit - his novel The Highest Mountain had been adapted for the screen as The River's Edge (1957), a crime thriller starring Ray Milland and Anthony Quinn. Nathan E. Douglas had no film background at all...or so it was thought. But his real name was Nedrick Young, and he had been blacklisted for refusing to name names to Congress during the anti-Communist witch hunts of the early fifties. His last credit had been for story only (as Ned Young) on the Elvis Presley movie Jailhouse Rock (1957). Before that he had fronted for another blacklisted writer, Alvah Bessie, on Passage West (1951), and had a handful of B-movie screenplays to his credit. As Ned Young, he also acted in a number of films, including the cult classics Gun Crazy (1950) and House of Wax (1953). It was risky for Kramer to consider producing a blacklisted writer╒s work, but it was exactly the kind of risk the producer-director was most likely to take, especially for a script he found as "interesting and refreshing" as The Defiant Ones.

Prior to The Defiant Ones, Sidney Poitier had been gaining more and more recognition through his work in such films as Cry the Beloved Country (1952), The Blackboard Jungle (1955), and Edge of the City (1957). He had been called to Hollywood to meet with Sam Goldwyn concerning the role of Porgy in the film version of Porgy and Bess (1959), and while there his agent suggested they go see Stanley Kramer. Poitier greatly admired Home of the Brave (1949), the racial-themed film Kramer had produced, and Kramer's commitment "to address head-on those issues other producers were inclined to dance around." According to his autobiography, This Life (Knopf, 1980), Poitier read the script immediately "in a state of sweaty-palmed excitement." Then Poitier, Kramer, and the two writers quickly organized script meetings to kick around ideas and strengthen the piece. There was one hitch. Poitier wanted out of the Goldwyn picture which he felt lacked the acting challenges of The Defiant Ones. Poitier wrote that Kramer's film was "a rare look at a movie character exemplifying the dignity of our people, something that Hollywood had systematically ignored in its shameless capitulation to racism." But he knew if he backed out of Porgy and Bess, he could ruin his ruin in Hollywood, and Kramer was not willing to incur the wrath of the big studios either. He told Poitier that unless he went through with the Goldwyn picture or obtained an absolute firm release from the producer, Kramer would not sign him to do his picture. The release never came. As much as Poitier wanted out, he decided not to buck the system and anger Goldwyn. Still, the actor says Porgy is a role he regrets to this day.