WASHINGTON — The Justice Department is scooping up data from thousands of cellphones through fake communications towers deployed on airplanes, a high-tech hunt for criminal suspects that is snagging a large number of innocent Americans, according to people familiar with the operations.
The U.S. Marshals Service operates Cessna aircraft from at least five metropolitan-area airports, with a flying range covering most of the U.S. population, according to people familiar with the program.
Planes are equipped with devices — some known as “dirtboxes” to law-enforcement officials because of the initials of the Boeing Co. unit that produces them — that mimic cell towers of large telecommunications firms and trick cellphones into reporting their unique registration information.
The technology in the 2-foot-square device enables investigators to scoop data from tens of thousands of cellphones in a single flight, collecting their identifying information and general location, these people said.
People with knowledge of the program wouldn’t discuss the frequency or duration of such flights but said they take place on a regular basis.
A Justice Department official would neither confirm nor deny the existence of such a program. The official said discussion of such matters would allow criminal suspects or foreign powers to determine U.S. surveillance capabilities. Justice Department agencies comply with federal law, including by seeking court approval, the official said.
The program is the latest example of the extent to which the United States is pointing its surveillance lens inside the United States.
It is similar in approach to the National Security Agency’s program to collect millions of Americans’ phone records.
Christopher Soghoian, chief technologist at the American Civil Liberties Union, called it “a dragnet surveillance program. It’s inexcusable and it’s likely — to the extent judges are authorizing it — (that) they have no idea of the scale of it.”
Cellphones are programmed to connect automatically to the strongest cell tower signal. The device being used by the Marshals Service identifies itself as having the closest, strongest signal, even though it doesn’t, and forces all the phones that can detect its signal to send in their unique registration information.
Even having encryption on one’s phone doesn’t prevent this process.
The technology is aimed at finding cellphones linked to individuals under investigation by the government, including fugitives and drug dealers, but it collects information on cellphones belonging to people who aren’t criminal suspects, these people said. They said the device determines which phones belong to suspects and “lets go” of the non-suspect phones.
The device can briefly interrupt calls on certain phones. Authorities have tried to minimize the potential for harm, including modifying the software to ensure that the fake tower doesn’t interrupt anyone calling 911, one person familiar with the matter said.
The program cuts out phone companies as an intermediary in searching for suspects.
Rather than asking a company for cell-tower information to help find a suspect, which law enforcement has criticized as slow and inaccurate, the government can now get that information itself.
People familiar with the program say they do get court orders to search for phones, but it isn’t clear whether those orders describe the methods used because the orders are sealed.
Also unknown are the steps taken to ensure data collected on innocent people isn’t kept for future examination by investigators.
A federal appeals court ruled this year that over-collection of data by investigators, and stockpiling of such data, was a violation of the Constitution.
By taking the program airborne, the government can sift through a greater volume of information and with greater precision, these people said. If a suspect’s cellphone is identified, the technology can pinpoint its location down to a specific room in a building.
Newer versions of the technology can be programmed to jam signals and retrieve data from a target phone such as texts or photos.
Within the Marshals Service, some have questioned the legality of such operations and the internal safeguards, these people said.
It is unclear how closely the Justice Department oversees the program.
A Verizon spokesman said the company was unaware of the program. An AT&T Inc. spokeswoman declined to comment, as did a spokeswoman for Sprint Corp.
