Long article at source - required reading...

The public has an legal obligation to let the government know when they are displeased, and the only part that armed thugs in police uniforms need to play in this is to insure that the traffic flow continues (around the demonstrations), and that property is not destroyed. That's what they get paid to do. It is not the job of "police" to censor or to silence whatever the public has come out to say-to the so-called powers-that-be.

EXACTLY! Every cop in Pittsburgh involved in the G20 actions should face charges for hindering Constitutionally assured expression, at the very least.