The documents don’t describe the quality of tips provided by the NSA, or how often the FBI launched domestic criminal investigations because of the NSA’s information. They do suggest the agency has been active in forwarding investigative suggestions to the FBI. A recent presidentially appointed review of the program found the NSA phone surveillance program had not been essential to preventing attacks. The program’s defenders argue it has been an important counterterrorism tool…

The “three a day” average continued until March 2009, the last time it is referenced in the unredacted portions of the documents. The documents don’t offer any clues as to why officials stopped including that estimate. The same year, a secret surveillance court ordered a major review of the program after learning there were significant differences between what it was doing and what government lawyers had previously told the court.

In 2010, the court authorizations change again, dropping the previous language about the NSA tipping the FBI, and instead refer to it only as “information.”

An FBI spokesman didn’t immediately comment on the documents.