The plot deals with Charles Laughton's character recovering from a severe heart attack while defending Tyrone Power's character. In reality, this would be Tyrone Power's last complete film - he would die of a heart attack while on the set of his next film less than one year after release of this one.
Unsure if he could play a man with a heart condition, Charles Laughton (Sir Wilfrid) staged a heart attack in the pool one day at home. His wife, Elsa Lanchester (Miss Plimsoll), and a houseguest panicked and pulled him from the water, at which point he explained his trick. Elsa's reaction has not been recorded.
Marlene Dietrich was so certain she would be nominated for an Academy Award for her performance as Christine Vole that she recorded a new introduction to her Las Vegas show mentioning her nomination. She was not nominated, and was crushed.
When Leonard Vole (Tyrone Power) meets Mrs. French (Norma Varden) for the second time - in the movie theater - Vole tells Mrs. French that the movie is about Jesse James. Tyrone Power starred as the famous outlaw in Jesse James (1939).
While it is generally supposed that Agatha Christie chose the name Vole after the ratlike rodent of the same name, in fact the word has several other meanings also relevant to this character. In cards, a "vole" means the winning by one player of all the tricks of a game. And the expression "go the vole" can mean either to venture everything on the chance of great rewards, or to try one thing after another, usually a variety of occupations - all perfect descriptions of Christie's ingeniously named "Leonard Vole".
Charles Laughton modeled his characterization of "Sir Wilfrid Robarts," including the use of a monocle to intimidate Leonard, on Florance Guedella, an Englishman who was both Laughton's and Marlene Dietrich's lawyer and who was famous for twirling his monocle while cross-examining witnesses.
The film followed the basic story of Agatha Christie's play, but director and co-screenwriter Billy Wilder opened up the story by including numerous scenes that did not take place solely in the courtroom, as the play had, and changed the emphasis from "Leonard Vole" to "Sir Wilfrid Robarts." The character of "Miss Plimsoll" was added to the film, and the name of Leonard Vole's wife "Romaine" was changed to "Christine."
The Tyrone Power character's last name is Vole. Aside from what has already been mentioned, the word "voleur" in French translates in English to burglar, embezzler, housebreaker, intruder, peculator, robber, and thief. Many of which could apply to Power's character.
The press book, reviews and various articles about the production stated that the principal cast members themselves did not even know the ending of the film until the last day of shooting, when the final ten pages of the script were presented to them.
Although originally published as a short story in 1925 with the title "Traitor's Hands" by Agatha Christie, she renamed it "Witness for the Prosecution" when it was reprinted in the 1930's and 1940's in British and American publications. Her play is based on this short story.
All of the comic scenes in the film between Charles Laughton and Elsa Lanchester were added by the screenwriters; they are not in the original play. For the 1982 television remake the adapters followed this 1957 film version nearly word-for-word and retained many of the same scenes.
Less than two months after "Witness for the Prosecution" by Agatha Christie had a London premiere, it opened on Broadway at Henry Miller's Theater on December 16, 1953 and ran for 645 performances. Una O'Connor reprized her role in the movie.