The ownership of Zuccotti Park, Brookfield, would have had the denizens there formerly residing to lay siege to Wall Street removed without delay, and with no need for discretion (if you know what I mean, Commissioner).
However, and without a doubt known all along by at least some organizers and occupiers, Zuccotti Park was an area within a municipality known as public easement, a space heavily trafficked by the public and generally considered a provision for public use.
Police cannot arrest a group of people for infractions perpetrated by individuals. The only way that the Occupy Wall Street squatters could be removed en masse is for the crime of trespassing - impossible for otherwise lawfully present members of the public with a space designated as an easement. They had to wait and allow the circumstances to fester. Anyone as Joanne and I were present during the first week will easily remember the petty and ceaseless employment of tactical intimidation - vans full of cops lining the blocks in every direction. They and we both contributed to an escalation that led to the eventual violent and illegal crackdown on November 15th under a media blackout.
Occupy Birmingham has taken up a method that seems to be a possible static employment of public space common law - a modular, internally resourced camp that moves and expands according to the civic ecology.
Eventually, law enforcement, no matter how friendly, will likely be compelled from above, after increased pressure from corporate philanderers, to choose between people at a disadvantage and those who have put them in their disadvantaged state. Then it won't matter who knows and can cite building code or file a brief. But it's the path of least resistance for now - passive non-violence and fearless association with outlawed convictions.