A recent court ruling just made it harder for police to track down your cell phone. An Illinois district court judge issued new requirements earlier this month to better protect innocent bystanders from Stingray devices deployed in their vicinity. The cell-site simulators, whose constitutionality remains murky, are used to gather suspected criminals' cell phone information and location, but often pick up innocent people’s data in the process.

The new ruling instates three prerequisites before a Stingray can be used. The first is that law enforcement must "make reasonable efforts" to minimize the capturing of innocent people’s cell phone data. Police and federal agents could try to direct the cell-site simulator’s signal, for instance, or opt to use the device when fewer innocent people are near the target. This step could even help law enforcement cut back on time and effort, the judge said, since collecting fewer data points will make it simpler to identify the correct cell phone. The devices can pick up signals from hundreds of devices once deployed, which privacy advocates argue violates bystanders’ Fourth Amendment rights.

The second rule requires all data not relating to the pertinent cell phone be deleted within 48 hours of being collected. Just saying the data was deleted isn’t good enough, either; proof must be provided with the return of the issued warrant. Finally, officers cannot use any data it acquires during the Stingray’s use for anything other than identifying the target’s cell phone information. While there isn't much public information on the simulators' exact capabilities, it's known that they can provide law enforcement with more than a precise location and identifying cell phone information. They can also expose who is being called when, and with some devices, even the contents of a conversation. "A cell-site simulator is simply too powerful of a device to be used and the information captured by it too vast to allow its use without specific authorization from a fully informed court," the judge wrote in his opinion.

These new requirements follow the enactment of policies surrounding the devices by both the Justice Department and the Department of Homeland Security earlier this year. The agencies now explicitly require search warrants be issued before the simulators are deployed. While many privacy groups applauded the warrant requirements, they also said the rulings made exceptions and allowed for loopholes that still put innocent people's Fourth Amendment rights at risk. The requirements also don’t apply to many state and local police departments, which makes this recent hyper-local ruling relevant. California and Washington also both recently enacted state laws requiring warrants before police can deploy the devices.

These rulings attempt to rein in apparent Stingray abuse and overuse. Take police in Baltimore as an example when they used the device to hunt down a man accused of stealing a cell phone. The department also admittedly said it's used the devices "thousands" of times, The Baltimore Sun reported. The IRS has also used the devices to investigate money laundering operations related to drugs.