FBI surveillance devices may disrupt 911 calls, senator says

Cellphone tracking devices commonly used by the FBI and other federal and local law enforcement agencies have the potential to disrupt emergency 911 communications, a U.S. senator said this week, raising new concerns about whether the devices are a threat to individuals’ personal safety.

In a letter addressed to Attorney General Jeff Sessions, Sen. Ron Wyden, D-Ore., asked the Department of Justice to be more forthcoming about the potentially disruptive nature of cell tower simulators — also known as IMSI Catchers, or Stingrays — which law enforcement agencies and others use to covertly track suspects’ movements through their cellphones.

Citing conversations with unnamed executives from Harris Corporation, a Florida-based government contractor that makes a widely used cell tower simulator, Wyden wrote that the devices “completely disrupt the communications of targeted phones for as long as the surveillance is ongoing. According to Harris, targeted phones cannot make or receive calls, send or receive text messages, or send or receive data over the internet.”

Harris Corporation director of global public relations Jim Burke declined to answer questions about whether the company’s devices can interfere with U.S. citizens’ emergency call services. A Justice Department spokesman said: “We’re aware of the senator’s letter and will be reviewing it.”

Jonathan Mayer, a Princeton computer science professor who served as a technologist at the Federal Communications Commission (FCC), said the issue deserves close scrutiny.

“Anything that significantly interferes with 911 is a problem,” Mayer said. “And anything that could significantly interfere with 911 deserves a close look.”

The FBI says it primarily uses cell tower simulators to track suspects’ movements in high-stakes cases such as drug trafficking and child kidnapping, and that it does not collect data from the phones themselves. The U.S. government does not have a monopoly on them, however: The devices can be found for sale on Chinese e-commerce sites. And technologists have built their own devices from scratch.

In June the Department of Homeland Security found them deployed near the White House. One mobile security firm claims to have detected them outside major government buildings and embassies across Washington.

The devices’ wide-ranging use — and a web of nondisclosure agreements that limit the public’s view of how they work — has been a continuous point of contention for online privacy advocates.

In 2013 a trove of documents released through a Freedom of Information Act lawsuit revealed that federal investigators failed to fully detail the practice to judges authorizing warrants. Wyden’s letter revived those concerns, claiming that the Justice Department’s warrant applications understate how much the devices disrupt cell services.