“Professional courtesy” among police officers refers to the idea that cops should not arrest or ticket other cops for traffic violations. Balko explains how this custom leads to miscarriages of justice and invites serious corruption:
Police officers who fail to extend professional courtesy to fellow officers can face ridicule, shaming and other retaliation. It’s an extension of the “Blue Code of Silence,” the informal admonition that cops refrain from implicating other cops. Several years ago there was even a Web site called “Cops Writing Cops” which provided a forum for police officers to publicly shame fellow cops who had the audacity to ticket them. (The site has since been taken down.) A 2007 Seattle Post-Intelligencer study revealed that off-duty cops put stickers in the windows of their private vehicles to identify themselves to their fellow officers. And then there are outfits like “LEO Pro Cards,” a business that prints up handy, wallet-sized cards that cops and their family members can flash to request professional courtesy from other officers. …
You’ll often see the tradition defended as just a small, insignificant gesture between professionals who share a tough job. But if anything, cops should be held to a higher standard than everyone else. They are after all given the considerable power to arrest, detain and kill. Once cops start letting other cops off for traffic offenses, you begin to instill in some police officers the idea that they’re less beholden to the law than the average citizen, not more. It isn’t difficult to see how that could set the stage for more consequential corruption.
The Dish 