NYC Police Pursuing Technology To Scan Pedestrians For Guns The New York Police Department is working with the Department of Defense to further crack down on illegal guns in the city by researching technology that could detect concealed weapons on people as they walk down the street. Infrared rays would scan a "form of radiation emitted from the body" on a person carrying a gun on the city's streets, New York Police Commissioner Raymond Kelly said Tuesday at a State of the NYPD event, the New York Post reports. The technology, known as terahertz imaging detection, works on the basis that the rays cannot pass through metal, thereby creating a digital outline of where a gun is hiding on someone. And it can measure energy radiating off a body from up to 16 feet away, CBS New York reports. Kelly told the audience that the scanner would be used only when reasonable suspicious circumstances called for it and could decrease the instances of stop-and-frisks on the street, according to the TV station. But the news also has raised privacy concerns. It's worrisome. It implicates privacy, the right to walk down the street without being subjected to a virtual pat-down by the Police Department when you're doing nothing wrong," the New York Civil Liberties Union's Donna Lieberman told CBS New York. The Post reports the scanners would be mounted on NYPD vans, with the rays aiming at people on the street.