Police in Buffalo, New York, have used the controversial stingray surveillance tool 47 times since 2010 but obtained a court's permission only once. They also signed a gag order with the FBI, giving the federal bureau permission to intervene in criminal proceedings where secret details about the device’s capabilities might be revealed, a privacy watchdog said.

Police agencies throughout the U.S. use stingrays, also known as cell site simulators, to replicate the signal that comes from a cell phone tower, tricking area phones into connecting with the surveillance tool rather than the tower. This tactic gives police access to a variety of information about all the phones in the area, from text message data to phone numbers dialed and, in some cases, the owner's billing information.

Use of the stingray has been shrouded in secrecy, with state and federal law enforcement obscuring its use in court, or opting to reduce criminal charges in cases when judges demand an explanation.

The Erie County Sheriff's Office used a stingray 46 times without a court's permission between May 1, 2010, and Oct. 3, 2014.

“These records confirm some of the very worst fears about local law enforcement's use of this expensive and intrusive surveillance equipment,” New York Civil Liberties Union staff attorney Mariko Hirose said in a statement Tuesday. “Not only did the Sheriff's Office promise the FBI breathtaking secrecy to keep information about stingrays as hidden as possible, it implemented almost no privacy protections for the Erie County residents it is sworn to protect and serve.”

Not only do the records contradict Sheriff Timothy Howard's promise that the surveillance would be subject to judicial review, but the police also seem to have misled the judge in the single case when they did obtain a court order. In that case the stingray was identified as a pen register, a device that tracks what phone numbers a target dials. The stingray, on the other hand, tracks a device's location, movement and metadata.