The Minnesota Senate has passed a measure to restrict the use of cell phone-tracking devices by law enforcement agencies.
The bill, which was approved on a 56-1 vote Tuesday, requires police to obtain a warrant before they can track a person's location by monitoring his or her cell phone, MPR News reports.
The measure was authored by Sen. Branden Petersen, R-Andover, who said he's concerned about law enforcement using so-called “cellular exploitation devices” to pinpoint a person's location without their knowledge, according to MPR.
The devices, sold under names like Stingray, are designed to simulate a cell tower and capture information from cellphones -- including location data -- which can be done even when the phone is not being used to make a call.
Law enforcement agencies often track cellphone locations in real time to target suspects or missing persons — but they also can mine data from hundreds or thousands of unsuspecting people nearby, according to a report by Gannett News.
Stingrays don't intercept the content of the phone calls or text messages, Gannett reports, but they could possibly capture the numbers with which a phone is communicating, according to court records and published reports.
(Graphic: USA Today/Gannett)
Here's an interactive graphic produced by Gannett which illustrates how a Stingray works.
The Minnesota Bureau of Criminal Apprehension and the Hennepin County Sheriff's Office each have one of the devices, the Star Tribune reports.
The bill originally required police to obtain a search warrant to use the device, but Petersen agreed to an amendment that requires a "tracking warrant" instead, which is a bit less stringent and can be authorized for a longer period of time, according to the Star Tribune. The measure also includes a provision that anyone who was targeted for tracking must be notified of that fact within 60 days.
A companion bill in the House is awaiting action.
Debates about cellphone tracking are taking place in other states as well, including Michigan and California. In Wisconsin, the Legislature passed a bill in February requiring warrants to use cell phone tracking in most cases, according to Gannett. The measure has yet to be signed by Gov. Scott Walker.
The American Civil Liberties Union is also campaigning for more restrictions on the use of cellphone tracking devices.