All this police activity about and against “Occupy” encampments is in the news. The NYPD (after a false start a few weeks ago) seem to have done a good job. They conducted a couple of rehearsals and then bussed in a lot of policemen who (largely) handled it well. The protestors sat down, linked arms and a policemen or two picked them up and handcuffed them and took them someplace for some sort of procedure.
In Seattle, the police got policemen (on bikes!) to line up and doused the crowd with tear gas. You may have seen the photo of the Little Old Lady who was zapped. But note this, she was being led away by fellow protestors. It does not seem she was arrested.
*When do police departments decide to arrest, and when and why do they sometimes just want to disperse crowds? *