The director of the National Security Agency revealed Wednesday that the government collected Americans' cellphone location data in bulk as part of a secret pilot program in 2010 and 2011.
The program tracked the locations of an unknown number of people in the United States who were under no suspicion of wrongdoing.
At a Senate Judiciary Committee hearing, NSA Director Gen. Keith Alexander said the agency "received samples in order to test its systems" but that the cellphone location data was not used for any intelligence analysis.
"This may be something that would be a future requirement for the country, but it is not right now because when we identify a number, we can give that to the FBI," Alexander said. "When they get their probable cause, they can get the location data they need."
He said the NSA would have to receive permission from the Foreign Intelligence Surveillance Court to resume the indiscriminate collection of U.S. cellphone data.
Leaks by Edward Snowden revealed earlier this year that the NSA is using Section 215 of the Patriot Act to collect records on all U.S. phone calls. Those records include phone numbers, call times and call durations — but whether the NSA also collected cellphone location information had remained unclear.
At a Senate Intelligence Committee hearing last week, Sen. Ron Wyden (D-Ore.) asked Alexander about the existence of a location data program.
Alexander responded that the NSA is not currently collecting cellphone location data in bulk, but Wyden pressed the NSA chief on whether the agency had "ever" collected such information.
“What I don't want to do, senator, is put out in an unclassified forum anything that's classified here,” Alexander said at the time.
In a statement Wednesday, Wyden, who has access to classified information as a member of the Intelligence panel, said Alexander is still concealing information about the NSA's tracking of U.S. cellphones.
“After years of stonewalling on whether the government has ever tracked or planned to track the location of law abiding Americans through their cell phones, once again, the intelligence leadership has decided to leave most of the real story secret — even when the truth would not compromise national security,” Wyden said.
Whether the government needs a warrant to collect cellphone location data remains an open legal question. Police routinely collect other records from phone companies using only a subpoena.
But the Supreme Court ruled last year in United States v. Jones that planting a GPS tracking device on a suspect's car qualifies as a search under the Fourth Amendment.
“The NSA’s attempt to collect this data shows the need for stronger legislative oversight of the agency’s activities, but the fact is that federal, state, and local law enforcement are already regularly collecting cell phone location information without a warrant," Chris Calabrese, a lobbyist for the American Civil Liberties Union, said in a statement. "Last year a majority of the Supreme Court recognized that location information is sensitive, and we need legislation that respects privacy rights when it comes to Americans’ movements.”
—Updated at 3:48 p.m.