The Arrest of the Occupying Protestors

I think it was wrong to arrest the Wall Street Occupiers because, after all, they were on public property. They were not tresspassing. As long as they didn't have any alcohol or weapons on the park the Occupiers were fine. So how can the police ask people to leave public property? The Occupiers have every right to be there. In a conversation with my mother, she asked, "When does the park stop become property of the public?" If it is maintained by public dollars and if the public is assembled in an orderly fashion and no laws are being broken when does public property cease(stop) to become property of the public? Or are they just words being thrown around? Or are these just words that are used for political grandstanding? The Wall Street protestors' rights were violated when they were arrested. The Wall Street protestors were arrested because of the financial inconvience. Occupiers, please don't stop protesting!