A covert government initiative, known as Data Analytical Services, has been granting federal, state, and local law enforcement agencies access to the phone records of U.S. citizens, even those not suspected of any criminal activity, according to a letter from Senator Ron Wyden to the Department of Justice. The DAS program, previously known as Hemisphere, has been operational for over a decade, in collaboration with telecom giant AT&T. The program uses a technique called chain analysis to scrutinize not only the phone records of those in direct contact with a criminal suspect, but also anyone those individuals have communicated with.

The White House has reportedly funded the program with over $6 million in the past decade, enabling the targeting of any calls made using AT&T’s infrastructure. Wyden has expressed serious concerns about the legality of the DAS program, citing “troubling information” that he believes would outrage many Americans and members of Congress.

AT&T has declined to comment on the program, stating only that the company is legally obliged to comply with a lawful subpoena. However, there is no law mandating AT&T to store decades of Americans’ call records for law enforcement purposes.

The DAS program, which is managed under a program dedicated to drug trafficking, has been used by local police agencies for unsolved cases seemingly unrelated to drugs. The program was first disclosed by The New York Times in 2013 and has largely remained under the radar since then.

The White House has yet to comment on the issue.

Read more at Wired.