A magistrate has placed significant restrictions on the use of the “Stingray” cell phone tower spoofer:

A federal judge in Illinois has recently taken the unusual step of issuing three new stringent requirements for the government when it wants to deploy cell-site simulators. The move aims to protect the Fourth Amendment rights of innocent bystanders against unreasonable search and seizure.

Of course, for now, this order only applies to this one judge in the Northern District of Illinois.

These new stingray requirements come just about a month after the Department of Homeland Security imposed its own warrant requirement, following a similar move by the Department of Justice.


Not only can stingrays be used to determine location by spoofing a cell tower, but they can also be used to intercept calls and text messages. Once deployed, the devices intercept data from a target phone as well as information from other phones within the vicinity.

As part of an ongoing drug case, US Magistrate Judge Iain Johnston told prosecutors recently that they will now have to fulfill three distinct requirements before he will sign off on the use of the invasive surveillance devices, as a way to protect the privacy of those who happened to be near a surveillance target. The memorandum opinion came down earlier this month as part of a largely sealed ongoing drug investigation, the details of which the judge described as “unsurprising.”

What is surprising is Judge Johnston’s order to compel government investigators to not only obtain a warrant (which he acknowledges they do in this case), but also to not use them when “an inordinate number of innocent third parties’ information will be collected,” such as at a public sporting event.

This first requirement runs counter to the FBI’s previous claim that it can warrantlessly use stingrays in public places, where no reasonable expectation of privacy is granted.

Second, the judge requires that the government “immediately destroy” collateral data collection within 48 hours (and prove it to the court).

Finally, Judge Johnston also notes:

Third, law enforcement officers are prohibited from using any data acquired beyond that necessary to determine the cell phone information of the target. 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. Minimizing procedures such as the destruction of private information the United States has no right to keep are necessary to protect the goals of the Fourth Amendment.

I’m thinking that if someone could come up with an app that could detect when it is likely that one of these devices is in use, they sell it for a significant chunk of change.

I think that you could do that with an algorithm involving ping times to a cell tower.