"KASTE: Stephanie Pell has been researching this at the Army Cyber Institute at West Point, though her views here are not necessarily those of the Army. A former prosecutor, Pell says the devices are a legitimate tool for the police, but she's dismayed by the continued secrecy. It's no longer hiding what the devices can do, she says. It's just hiding how they're used.
PELL: The only person or people who know what was collected is the IMSI catcher operator. It makes after-the-fact oversight very difficult."
http://www.npr.org/2014/10/22/358120429/should-police-be-able-to-keep-their-devices-secretListen to the full interview at NPR.