Brad Heath reports at USAToday:
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.
Those agencies, including the FBI and the U.S. Marshals Service, began deploying the radar systems more than two years ago with little notice to the courts and no public disclosure of when or how they would be used. The technology raises legal and privacy issues because the U.S. Supreme Court has said officers generally cannot use high-tech sensors to tell them about the inside of a person's house without first obtaining a search warrant.
"Current and former federal officials say the information is critical for keeping officers safe if they need to storm buildings or rescue hostage," Heath writes. "But privacy advocates and judges have nonetheless expressed concern about the circumstances in which law enforcement agencies may be using the radars -- and the fact that they have so far done so without public scrutiny.
"The idea that the government can send signals through the wall of your house to figure out what's inside is problematic," USAToday quotes Christopher Soghoian of the ACLU as saying. "Technologies that allow the police to look inside of a home are among the intrusive tools that police have."
The Supreme Court in 2013, "limited police's ability to have a drug dog sniff the outside of homes. The core of the Fourth Amendment, Justice Antonin Scalia wrote, is 'the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion'," USAToday reports.