It's purely my experience; and I suppose it's advice that I personally follow.
I'll be the first to admit that no instance in my life has ever put me in a position to ever need to follow that advice.
I've never experienced or personally witnessed (obviously, I'm not counting videos on the news, etc.) anything remotely resembling police brutality or abuse of authority (by law enforcement), and I've never met anyone who themselves personally witnessed or experienced the same--I'm not trying to imply that it doesn't happen, only to indicate that I have a very, very limited frame of reference.
With this in mind, I can have an opinion but I can't contextualize that opinion or qualify it: I never meant anyone to understand that I believe the victims of police violence or abuse of authority caused their own problems.