A crime film, in the most general sense, is a film that involves various aspects crime and the criminal justice system. Stylistically, it can fall under many different genres, most commonly drama, thriller, mystery and film noir. Films focused on the Mafia are a typical example of crime films.

Plays and films

Films dealing with crime and its detection are often based on plays rather than novels. Agatha Christie's stage play Witness for the Prosecution (1953; based on her own short story, published in 1933) was adapted for the big screen by director Billy Wilder in 1957. The film starred Marlene Dietrich and Charles Laughton and is a classic example of a "courtroom drama." In a courtroom drama, a charge is brought against one of the main characters, who says that they are innocent. Another major part is played by the lawyer (in Britain 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. But 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.