Federal agencies and local police are using a new device to look inside homes and buildings, reports USA Today.
The device, called the Range-R, operates like a stud-finder except instead of detecting studs inside a wall, it detects motion beyond the wall, including breathing as far as 50 feet away.
The U.S. Supreme Court has previously ruled that police may not use high-tech devices to see inside people's homes without a warrant, raising questions about how this device has so far been used.
"The idea that the government can send signals through the wall of your house to figure out what's inside is problematic," Christopher Soghoian, the American Civil Liberties Union's principal technologist, told USA Today. "Technologies that allow the police to look inside of a home are among the intrusive tools that police have."
The FBI did not respond to NPR's request for comment. The US Marshals referred questions about their use of the device to the U.S. Justice Department.
Justice Department spokesman Patrick Rodenbush declined to say how and how often the device was being used but said in a statement that the department is looking over an appellate court ruling out of Denver that questioned the use of the device.
"While it is our position to not discuss or disclose any investigative techniques, the Department of Justice is currently reviewing the 10th Circuit Court of Appeals ruling," Rodenbush said.
The Radar-R is made by L-3 Communications, which develops military and police equipment.
A spokesman for L-3 Communications also declined to answer questions about the device including how many of them the company has sold or which agencies it has sold them to.
According to USA Today, the company has sold 200 of the devices to 50 law enforcement agencies.
The company's website says the Range-R is a "highly sensitive handheld radar system" that can sense movement through walls constructed of "common building materials."
It says the device works in seconds with "continuous wave radar technology." CyTerra suggests it would be useful for firefighters, search and rescue teams, and police and swat teams.
The Denver federal appeals court cited an instance the device was used in a ruling last month. In that case, officers used the Radar-R to locate a parole violator inside a home. The officers had a warrant for the arrest of the man but did not have a warrant to search the home.
The judges wrote: "The government's warrantless use of such a powerful tool to search inside homes poses grave Fourth Amendment questions."