Talk unreasonable search and seizure, so If I have something metal like a cell phone or a insulin pump under my clothes i'm going to be subject to search because the machine thinks it is a gun? This just goes too far, in Airports I can understand, to get into certain high profile events like new years eve @ time square, or federal buildings I can understand but just to walk down the street is too far. This is a bad idea, because unless it someone JUST sees guns and bomb vests the police are going to be dealing with a lot of false positives and a lot of lawsuits because of it.
If this system ever does go live i would love to organize a protest where about 10,000 people took metal objects vaguely but not really shaped like guns, stuck them in their coats and then walked around NY just causing havoc with police responces. Knowing the NYPD they would probably just open fire, shoot first ask questions later.