There is virtually zero command and control in New Orleans, particularly with their police force. Up to 2/3rds just up and dissapeared, either dead, evacuated, or just aren't reporting in. The few that are left are desperately short on radios. Most of the various police headquarters around the city are either underwater or are just unoccupied and not working. Many of the remaining officers have received no orders whatsoever in up to three days, and have received no rules of engagement so they can't really do anything. Shooting someone would only get the other 500 looters/rapists/criminals shooting back at you, with no hope of receiving any backup. Even if they arrested someone there's nowhere to take them. All they really can do is sit back and watch and maybe do something if something gets really out of hand. As time goes on and people learn that the police have no power aside from the simple deterrence of them being there the criminals will get more brazen, and we're seeing just that.
