Oh NYPD. Fourth Amendment anyone? Kyllo? Common use?

The NYPD is developing a new device that can detect whether a perp is carrying heat without frisking him, Commissioner Ray Kelly announced today.

The large mechanism uses infrared rays to scan a “form of radiation emitted from the body” of someone who is concealing a gun on the streets of the Big Apple, Kelly said at the Police Foundation’s State of the NYPD breakfast.

Since the infrared rays cannot pass through metal, the device provides officers with a digital outline of exactly where the firearm has been tucked away on the subject’s body, Kelly said.