In my vast experience on American soil for which the better part of two decades I was an outlaw of sorts (non-violent of course) I've never personally seen the police misbehave, quite the contrary, I've only ever seen the police doing their job in a professional manner. Much less have I experienced any type of "police state." In fact, there have been several times in my life when I wished there were lots of head bashing authoritarian types of cops around to put some thugs in their place.
My hypothesis, which bears fruit from 50+ years of anecdotal experience on American soil, is that if you have a valid drivers license, a decent looking car that is insured, have no warrants out for your arrest, aren't out in public running your mouth and looking for trouble, and pay your taxes, that the police are your friends not your enemies. And you can never have too many friends. We need more police in America that are tougher on perps.