Crime films are often based on or are adaptations of plays or novels. For example, the 1957 film version of Witness for the Prosecution is an adaptation of a 1953 stage play of that name, which is in turn based on Agatha Christie's short story, originally published in 1933. The film version was remade in 1982, and there have been other adaptations. However, each of these media has its own advantages and limitations, which in the case of cinema is the time constraint.
Witness for the Prosecution is a classic example of a "courtroom drama". In a courtroom drama, a charge is brought against one of the main characters, who claims to be innocent. Another major part is played by the lawyer (in England a barrister) representing the defendant in court and battling with the public prosecutor. He or she may enlist the services of a private investigator to find out what really happened and who the real perpetrator is. However, in most cases it is not clear at all whether the accused is guilty of the crime or not—this is how suspense is created.
Often, the private investigator storms into the courtroom at the very last minute in order to bring a new and crucial piece of information to the attention of the court. This type of literature lends itself to the literary genre of drama focused more on dialogue (the opening and closing statements, the witnesses' testimonies, etc.) and little or no necessity for a shift in scenery. The auditorium of the theatre becomes an extension of the courtroom. When a courtroom drama is filmed, the traditional device employed by screenwriters and directors is the frequent use of flashbacks, in which the crime and everything that led up to it is narrated and reconstructed from different angles.
In Witness for the Prosecution, Leonard Vole, a young American living in England, is accused of murdering a middle-aged lady he met in the street while shopping. His wife (played by Marlene Dietrich) hires the best lawyer available (Charles Laughton) because she is convinced, or rather she knows, that her husband is innocent. Another classic courtroom drama is U.S. playwright Reginald Rose's Twelve Angry Men (1954), which is set in the jury deliberation room of a New York Court of Law. Eleven members of the jury, aiming at a unanimous verdict of "guilty", try to get it over with as quickly as possible. And they would really succeed in achieving their common aim if it were not for the eighth juror (played by Henry Fonda in the 1957 movie adaptation), who, on second thoughts, considers it his duty to convince his colleagues that the defendant may be innocent after all, and who, by doing so, triggers a lot of discussion, confusion, and anger.
Crime films may fall under several different subgenres. These include: