The Senate Judiciary Committee is pressing the FBI and the Obama Administration to offer them assurances on recent changes to their legal policy with respect to the use of spyplanes to collect Americans’ cellphone data.

Revealed last month, the program has been active since 2007, and sees Boeing-made “dirtbox” planes flying over major US population centers, pretending to be cellphone towers to trick Americans’ cellphones into giving them data.

The FBI is said to have significantly changed the restrictions in recent months, centering around the “no assumption of privacy in public places” legal argument, and the committee is pushing for reassurances.

With the Judiciary Committee’s leadership changing next week it isn’t clear how much the committee’s stance will change, though presumptive incoming chair Sen. Chuck Grassley (R – IA) signed the letter seeking more information on the policy’s privacy ramifications.