Procedural drama in the context of "M (1931 film)"

The police procedural, police show, or police crime drama is a subgenre of procedural drama and detective fiction that emphasises accurate depiction of the investigative procedure of police officers, police detectives, or law enforcement agencies as the protagonists, as contrasted with other genres that focus on non-police investigators such as private investigators (PIs).

However, there is more to the police procedural than simply featuring a police officer as the protagonist. Many mysteries that feature a policeman as the hero, Earl Derr Briggers's series of novels featuring Honolulu Police detective Charlie Chan, Ngaio Marsh's series of novels and short stories about Roderick Alleyn of Scotland Yard, or the TV series Columbo, to use three famous examples, are not meant as authentic depictions of the law enforcement profession, but are merely giving the protagonists an official position so that they have a "franchise," so to speak, from which to work.