The New York Police Department has used cell-site simulators more than 1,000 times between 2008 and May of 2015, according to a new report from the New York Civil Liberties Union. The information comes in response to a Freedom of Information Law request filed by the organization last year.

Commonly referred to by the brand name Stingray, cell-site simulators work by masquerading as 2G cell towers, pulling information from all nearby phones but disrupting cell service throughout the area. The NYPD has never acknowledged using Stingrays, although departments in Baltimore and Chicago have already come clean about using the device, and many have speculated that Stingrays might be in use in the city.

The NYPD has no written policy for the use of cell-site simulators, but according to the FOIL response, they were typically accompanied by a low-level court order rather than a warrant, a practice that is common in police departments throughout the country but has drawn criticism from a number of civil liberties groups. In September, the Justice Department publicly broke with this practice, requiring that all federal law enforcement agencies acquire a search warrant before deploying a cell-site simulator.

Although such devices have been in use for more than a decade, their use was largely unknown until 2011, when a prisoner named Daniel Rigmaiden revealed their use as part of his appeal. In the years since, the devices have been discovered in nearly every corner of law enforcement, including a secret US Marshals program that deployed the devices in airborne planes to locate fugitives while flying over a city.