At least 50 U.S. law enforcement agencies have secretly equipped their officers with radar devices that allow them to effectively peer through the walls of houses to see whether anyone is inside, a practice raising new concerns about the extent of government surveillance.
The radars work like finely tuned motion detectors, using radio waves to zero in on movements as slight as human breathing from a distance of more than 50 feet. They can detect whether anyone is inside of a house, where they are and whether they are moving.
HOW IT WORKS
“The idea that the government can send signals through the wall of your house to figure out what’s inside is problematic,” said Christopher Soghoian, the American Civil Liberties Union’s principal technologist. “Technologies that allow the police to look inside of a home are among the intrusive tools that police have.”
Agents’ use of the radars was largely unknown until December, when a federal appeals court in Denver said officers had used one before they entered a house to arrest a man wanted for violating his parole. The judges expressed alarm that agents had used the new technology without a search warrant, warning that “the government’s warrantless use of such a powerful tool to search inside homes poses grave Fourth Amendment questions.”
By then, however, the technology was hardly new. Federal contract records show the Marshals Service began buying the radars in 2012, and has so far spent at least $180,000 on them.