Blue Wall Of Silence Meaning

(idiomatic) Strict secretiveness maintained by the members of a police force with respect to information which might be contrary to their interests, especially information concerning questionable police actions.

Example: 1985 June 25, Sydney H. Schanberg, "New York: The Concrete Wall of Silence," New York Times (retrieved 12 Aug 2012):
  We've all heard of the Blue Wall of Silence, the code under which cops stay mum about rogue cops who poison the barrel.
1999 May 25, Frank Pellegrini, "Too Despicable for the Blue Wall of Silence," Time:
  When the blue wall of silence broke, it was all over for New York City police officer Justin Volpe. The witnesses for the prosecution had badges, and they had stories to tell.
2008 July 15, Brandt Williams and Elizabeth Stawicki, "Minneapolis cop indicted on corruption charges," Minnesota Public Radio (retrieved 12 Aug 2012):
  The indictment of officer Michael Roberts also highlights another color barrier that can complicate matters of police discipline—that's the so-called blue wall of silence. Former Minneapolis police officer Mike Quinn says that wall is what keeps some cops from turning in their fellow cops.
2009 June 6, Donald Winkfield, "Manhattan DA’s Keystone Verdict," Black Star News (retrieved 12 Aug 2012):
  On the streets it is called "No snitching." In law enforcement it is called "The blue wall of silence".