The Thin Blue Line" is a 1988 documentary film directed by Errol Morris, which investigates the case of Randall Dale Adams, a man who was sentenced to death for the murder of a police officer in Dallas, Texas. The film presents evidence that suggests Adams was wrongfully convicted and that another man, David Harris, was actually responsible for the crime.

The thesis of "The Thin Blue Line" is that the criminal justice system can make mistakes and that the power of the law can sometimes be abused by those who are supposed to uphold it. Morris argues that the investigation and trial of Adams were flawed and biased, and that Harris, who had a history of violence and had been stopped by the police on the night of the murder, was the real perpetrator.