Thin lines: You're doing it wrong.
During the Crimean War, on October 25, 1854, 'wayyyyy out on the southwestern tip of the Crimean Peninsula, the British Army had a little fight on their hands. Pulling back repeatedly, the Brits held the port of Balaclava, but their forces were meager, and they were in no state to fight.
Placed in charge of the port's security was the 93rd Highland Regiment, with some help from the Royal Marines. They were In Grave Trouble. The Russian forces were coming hard and fast, and vastly outnumbered the British defense force. The Brits had already pulled back, spiking their guns before the oncoming Cossacks, and now found themselves with nothing behind them but Balaclava and the cold Black Sea, as a force of 2500 Russian cavalry advanced hard upon them.
Sir Colin Campbell, a man who thought of his men like family, spread his forces in a line two deep, between the oncoming Russian mounted force and the port that they were charged with defending. He told them that there was no retreat. He told them that they would die where they stood, if need be. The message was clear: hold the line.
Now, standard doctrine would be to place the men four deep, so that there was some redundancy. But Campbell didn't haven many men (a bare few hundred), and if he were to put up a proper defensive line without being flanked immediately, he had to spread them thinner. If any man fell, or ran away, he left a hole in the line that would allow the oncoming cavalry to penetrate the line and overwhelm his comrades. They depended on each other to each do his own part, to prevent the enemy from overrunning the port.
The men held. They fired three volleys at the fast-moving Russian cavalry. British Journalist William H. Russell, watching from a nearby high point, later wrote that the only thing between Balaclava and the rapidly-approaching Russian cavalry was "a thin red streak tipped with a line of steel," meaning the 93rd Regiment (wearing the red uniform jackets of the era).
The Russians checked their charge, and turned back. Some have said that they thought that it must be a trap, because their apparent opposition was so thin. Others have claimed that the fierce fighting of the 93rd stopped them. The truth probably falls somewhere in between, but it is clear that without the courage of the men to stand their ground and fight, maintaining their Thin Red Line, they would not have carried the day.
The term "Thin Red Line" took on the meaning of that vastly-important role that sheer grit and determination, even when unsupported by much tangible substance, plays in preventing civility from being overrun by the barbarians at the gate.
The term was, at some time in the late 20th century, applied to the force of police officers who serve to prevent crime and anarchy in our society. As the police traditionally wear blue, this application of the term became known as "The Thin Blue Line."
All well and good. I like the concept. Often our job, as police officers serving our society, is simply to patrol, and be seen, and stand by, being ready, should it come to it, to intervene. It is appropriate that in a free society the line of police be thin, as this is not a police state. The important thing is not to let your society down, by letting the "fight" against crime and anarchy go unserved. Skip patrols, fail to perform investigations and make important arrests, and the line is broken; the criminals break through, and society can become overrun. We are there to protect our society.
But it's true that among society are an officer's fellow police officers. If police fail to take action against dangerous criminals, then it is certainly true that they put their fellow officers at greater risk. To that extent, the concept of the Thin Blue Line also means protecting your fellow police.
THE "THIN BLUE LINE" DOES NOT MEAN THAT WE COVER UP FOR EACH OTHER.
There seems to be a fairly common public perception that "The Thin Blue Line" is a code of protection at all costs, by the police and for the police. This perception often seems to include the belief that most if not all officers are wrapped up in a cult-like fraternity that demands allegiance to the badge at all costs, which includes lying for a "brother officer," or tampering with evidence, to prevent other officers getting in trouble.
That's not the case.
An officer who knowingly breaks the law is not a police officer; he's a criminal who happens to have a badge. He's not my "brother," he's someone that we need to get shed of our professional association. The Thin Blue Line concept doesn't mean that I should protect a criminal officer; it means that I should take firm action against him.
If you're a cop, and you've been putting "Thin Blue Line" decals on your car, or images up on your website, or tattoos on your arm, or pins on your lapel, or whatever, consider what the meaning is for you, and what meaning the public at large thinks you're portraying.
While I do very much enjoy the camaraderie of my friends (and family) among the the law enforcement community, I'm not willing to let myself be thought of as intimidating others with my status, or as someone who's trying to be excused from a personal responsibility to abide by the law.
If you're using the term "Thin Blue Line" to mean a code of covert mutual protection among the law enforcement community, I submit that "You keep using that term. I do not think it means what you think it means."