<P> It is unknown when the term was first used to refer to police . In the 1950s, LAPD Chief Bill Parker used the phrase in the department - produced television show of the same name . Parker coined the term thin blue line to further reinforce the role of the LAPD . As Parker explained, the thin blue line, representing the LAPD, was the barrier between law and order and social and civil anarchy . The phrase is also documented in a 1965 pamphlet by the Massachusetts government, referring to its state police force, and in even earlier police reports of the NYPD . By the early 1970s, the term had spread to police departments across the United States . </P> <P> Use of the term became especially widespread following the release of Errol Morris' 1988 documentary film The Thin Blue Line, about the murder of a Dallas Police officer Robert W Wood . Judge Don Metcalfe, who presided over the trial of Randall Adams, states in the film that prosecutor "Doug Mulder's final argument was one I'd never heard before: about the' thin blue line' of police that separate the public from anarchy ." The judge admitted to being deeply moved by the prosecutor's words, though the trial resulted in a wrongful conviction and death sentence . </P> <P> Proponents say that the idea behind the various graphics that incorporate a thin blue line is that law enforcement is a Thin Blue Line that stands between chaos and order or between criminals and the potential victims of crime, and it is primarily used to show solidarity with police . Opponents note that the representations of the public and the criminals as black bars on either side of the blue line are identical, and suggest that the symbology represents a police vs. everyone else mindset . </P> <P> The Blue Line Identifier TM, consisting of a single horizontal blue line on a black field, is a registered trademark of Blue Line Productions, Inc . The Blue Line Identifier was developed by Blue Line Productions, Inc., in 1993 and used to identify authentic Blue Line Productions, Inc., goods sold only to certified law enforcement officers . The trademark applies to only the graphic, and not to the concept of the "Thin Blue Line" discussed in this article . </P>

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