I agree with FMJ. You can't push and not expect to be pushed back. It goes both ways.
While a lot of cops are dirty fucking assholes, there are guys out there just doing their job. I mean, if I see my buddy get beaned with a rock...I'm gonna be pissed and lash out.
I'm not saying it's right, but it's just the way it goes. The cops aren't the problem, it the couple of guys telling them what to do. Those are the ones that are the real problem. Police are juste a product of this fucked up system.