Local and state law enforcement in 15 states use fake cell towers, also known as “stingrays,” according to a map released by the American Civil Liberties Union on Thursday. Stingrays are used to track the location of targeted phones, and can also intercept phone calls and text messages.
According to the ACLU, when these devices are used to track a suspect, stingrays inadvertently track the information of bystanders’ phones. Stingrays can also send electronic signals into private residences, learning data about the owners and locations of phones within the buildings, which worries privacy advocates.
Besides the 15 states named in the ACLU’s report, the ACLU also listed 12 U.S. government agencies that use stingrays, including the National Security Agency and the U.S. Army.
The ACLU’s new map comes just two days after an activist filed a lawsuit against the Chicago Police Department, demanding to know how the city uses its own stingray devices.