At long last, the U.S. Department of Justice (DOJ) has announced a slew of much-needed policy changes regarding the use of cell-site simulators. Most importantly, starting today all federal law enforcement agencies—and all state and local agencies working with the federal government—will be required to obtain a search warrant supported by probable cause before they are allowed to use cell-site simulators. EFF welcomes these policy changes as long overdue.

Colloquially known as “Stingrays” after Harris Corporation’s brand name for a common model, cell-site simulators masquerade as legitimate cell phone towers, tricking phones nearby into connecting to them. This allows agents to learn the unique identifying number for each phone in the area of the device and to track a phone’s location in real time. But Stingrays can get a lot more than just identifying numbers and location data—by virtue of the way they work, all mobile traffic (voice, data, and text) from every phone in the area could be routed through the Stingray, giving the operator the option to do anything from recording entire calls and texts, to selectively denying service to particular phones.

Until recently, law enforcement’s use of Stingrays has been shrouded in an inexplicable and indefensible level of secrecy. At the behest of the FBI, state law enforcement agencies have been bound by non-disclosure agreements intended to shield from public scrutiny all details about the technical capabilities and even model numbers of the devices. Law enforcement has gone to extreme lengths to protect even the most basic information about them, even dropping charges rather than answering judges’ questions about them. Although today’s policy changes don’t directly affect the non-disclosure agreements already in place, the tone of the announcement, along with a clarification from May, gives us hope that more transparency is on the way.

What today’s changes do:

Federal law enforcement agents will be required to obtain a search warrant supported by probable cause prior to using a cell-site simulator in a law enforcement context. A search warrant requires a showing by the agent, under oath, that meets one of the highest standards in federal law. This incredibly important change is precisely what EFF has been asking for.

to using a cell-site simulator in a law enforcement context. A search warrant requires a showing by the agent, under oath, that meets one of the highest standards in federal law. This incredibly important change is precisely what EFF has been asking for. Agents will only be allowed to use Stingrays in “pen register” mode, meaning the devices will collect only the basic location of the phone and the numbers of incoming and outgoing calls and texts. Agents will not be allowed to collect the content of your communications -- like your emails or text messages -- even if the cell-site simulator is capable of such collection.

Finally, Agencies must delete data on users not targeted in either 24 hours or 30 days, depending on context.

What today’s changes don’t do:

The new policy isn’t law and doesn’t provide any remedy to people whose data is swept up by Stingrays operated without a warrant. Indeed, it won’t even act to keep evidence collected in violation of the policy out of court (this is known as suppression).

The policy doesn’t apply to the use of Stingrays outside of the criminal investigation context. For instance, when federal agents use cell-site simulators for “national security” purposes, they won’t be required to obtain a warrant by the terms of this policy.

There are two enumerated exceptions to the warrant requirement in today’s guidance. The first is the traditional “exigent circumstances” exception, common to all warrant requirements and not particularly worrisome. But the second exception listed in today’s policy for undefined “exceptional circumstances” is potentially problematic. We have no idea what that means, so we’re waiting to see if and how the exception will be used.

What more is needed:

While we’re pleasantly surprised by this long-needed first step to bring Stingrays out of the shadows and into compliance with the Fourth Amendment’s warrant requirement, more is needed.

First and foremost, without a statute or court decision giving this voluntary policy the force of law, there will be no consequences if law enforcement agents flout its terms and continue using Stingrays as they have—without warrants. With only this policy shielding us, there’s nothing keeping warrantless Stingray evidence out of court, and therefore nothing to deter agents from behaving badly.

And finally, we need to extend this warrant requirement to all state and local law enforcement agencies around the country. Some states (such as Washington) already have such laws in place. It’s time to make the message clear to cops in all 50 states: if you want to use a Stingray, get a warrant!