A measure requiring cops to get a warrant before using devices to track cell phones overwhelmingly passed the Minnesota Senate 56-1 Tuesday.

Sen. Branden Petersen's bill was authored in response to concern about "cellular exploitation devices" marketed under names like the Kingfish and Stingray, which mimic local phone towers to capture data and location information of cellular phones in a given area. The Minnesota Bureau of Criminal Apprehension has one; so does the Hennepin County Sheriff's Office.

The original bill by Petersen, R-Andover, required a search warrant to use the devices, and requires that people tracked by the devices be notified afterward by law enforcement. The devices are currently used with authorization by court order, which is less stringent than a search warrant.

However, a floor amendment during modified the bill to require "tracking warrants" rather than search warrants. While both require a statement of probable cause and signoff by a judge, a tracking warrant is less specific in its requirements than a search warrant, and in many cases is exempt from case law pertaining to search warrants. A tracking warrant also allows law enforcement to cross jurisdictions and can be authorized for a longer period of time.

Petersen said the provision was a last-minute compromise with the Minnesota Bureau of Criminal Apprehension, and is what resulted in the near-unanimous vote. Sen. Bill Ingebrigtsen, R-Alexandria, was the lone dissenter.

"In the interest of moving the bill, we ceded that part to law enforcement," Petersen said, adding that the bill still makes great strides in protecting citizens' rights.

="We're increasing the privacy threshold, increasing the standard and for the first time requiring that every person be notified after 60 days that they have in fact been searched," Petersen said. "This has a degree of transparency and accountability to it."

The bill's House Companion awaits floor debate.