The Missouri Senate has passed a bill requiring law enforcement officers to get a warrant before using cell site simulators to track a suspect's phone.
The bill would require a warrant for officers to use devices that mimic cell phone towers to pinpoint electronic devices in real time. The devices are also identified by their brand name Stingray.
The American Civil Liberties Union says that it has identified 72 law enforcement agencies in 24 states that own Stingrays.
Lawmakers in at least seven other states have introduced related proposals this year putting restrictions on the devices. At least 13 other states have already passed laws requiring police to get warrants to track cellphones.
The bill now goes to the House for final approval.
