Walls of silence.

"Walls of silence", as in, the "blue wall of silence", behind which
it is "alleged" that police officers protect each other from honest
accountability for each others misconduct.

There is a similar "wall of silence" behind which good ol' boys
protect each other from honest accountability for each others'
corruption and/or incompetence.

Which begs a question; what color is their wall?

Brown makes sense; so does green; and yellow does too.