Thin blue line 

UK useage.

The police in an area notorius for it's highcrime rate eg Whitechapel in East London, The Barton Hill area of Bristol, Bootle in Liverpool, the cornish town of Bude etc.

So called because said police see themselves as the only thing preventing an out break of anarchy

With 19 muggings, 34 assaults, 4 street fights, 7 car jackings, a rape, a murder and only 6 police the thin blue line is being streached tonight.

Thin blue line by black flag June 2, 2004

thin blue line 

the banding of all cops in any state despite right or wrong. The reason why NYC police only have cameras in their highway cars

All police rely on the thin blue line

thin blue line by Anonymous November 1, 2003

Thin Blue Line 

Thin Blue Line is the symbol pedophiles use to identify each other. Usually worn by racist police and their supporters.

The Thin Blue Line symbol, I would argue, is positive from the Canadian policing perspective and certainly a Calgary policing perspective - Calgary Police Chief Mark Neufeld - 2021

Thin Blue Line by lolwtfbbq42069 March 24, 2021

Thin Blue Liner 

The Law Enforcement equivalent of Black Lives Matter, aka Blue Lives Matter.

A person that is irrationally compelled to defend all law enforcement officers from accusations of criminal activity, regardless of the evidence presented or the facts.

This type of person often owns Blue Lives Matter merchandise and sees law enforcement as "super heroes".

"Be careful not to mention that pedophile cop news story around Steve. He's a Thin Blue Liner, and I will never hear the end of it."

Thin Blue Liner by Aliel of the New Dawn June 14, 2018