WASHINGTON, Jan. 20 (UPI) -- Radar developed to allow the U.S. military to see into homes has spread to police departments, USA Today reported Tuesday.

At least 50 law enforcement agencies, including the FBI and the U.S. Marshals Service, are using the handheld Range-R devices. The newspaper said some began using them more than two years ago with no public notice.


Since 2012, the Marshals have spent at least $180,000 on the devices, according to federal records. They can determine how many people are in a house and their locations, using radio waves that can detect motion as slight as human breathing.

In December, a U.S. appeals court in Denver upheld the arrest of an alleged parole violator by federal marshals that involved the use of Range-R. But the judges expressed misgivings about the technology, saying there is "little doubt that the radar device deployed here will soon generate many questions for this court."

In 2001, the U.S. Supreme Court ruled police needed a warrant before using thermal imaging to detect heat in a home.

Christoper Soghoian, principal technologist for the American Civil Liberties Union, suggested high-tech surveillance can be more intrusive than police breaking down the door. He added that the secret introduction of technology prevents public debate.

"What happens in your home is supposed to receive the highest level of protection under the law," Soghoian said. "At least if the police kick down your front door or knock on your front door and demand to come in, you know they are looking inside...you can at least voice your opposition. When the police use a device like this, you have no idea that they are doing it."

USA Today reported that other advanced technology is available that allow police to get data from cell phones. "When law enforcement agencies introduce surveillance technology without telling Congress and the courts it short circuits democracy," Soghoian said.