Abstract
The “blue wall of silence” -- the rule that police officers will not testify against each other -- has its roots in an important associational virtue, loyalty, which, in the context of friendship and familial relations, is of central importance. This article seeks to distinguish the worthy roots of the “blue wall” from its frequent corruption in the covering up of serious criminality, and attempts to offer criteria for determining when to testify and when to respond in other ways to the flaws of fellow officers.