The long speeches written for Bock and other characters by Chayefsky, later praised by critics, met resistance from United Artists executives during the making of the film. The script was described as "too talky" and containing excessive medical terminology. But Chayefsky, as producer, prevailed. He also vetoed the studio's suggestion that Walter Matthau or Burt Lancaster be hired for the lead role, insisting on Scott. Chayefsky worked on the dialogue with Diana Rigg, the female lead, but Scott rejected his input.