The premise of the film, that the protagonist must tell the truth for the next 24 hours, is based on a play of the same name written by James Montgomery, itself loosely adapted from the novel by Frederic S. Isham. The book and play had previously formed the basis of an earlier movie, also called "Nothing But the Truth", starring Richard Dix and Wynne Gibson. The 1941 film follows the plot of the play much more closely than the 1929 version. The same premise was used for a 1997 Jim Carrey movie, "Liar Liar".