Kentucky Republican Senator Rand Paul sent a letter to the Bureau of Alcohol, Tobacco, Firearms, and Explosives seeking information on a program which monitors firearm owners.

The lawmaker asserted in his letter last week to ATF Acting Director Daniel Driscoll that the monitoring program allows agents to request for the FBI to monitor specific individuals using the National Instant Criminal Background Check System without the knowledge of those individuals.

Paul therefore asked Driscoll for unredacted records “showing how many Americans have been subjected to this monitoring, for what reasons, the legal basis for the program, whether it has led to prosecutions, and whether there has been any misuse by ATF personnel or contractors.”