Thanks to EFF and the ACLU, the government has finally admitted it secretly used a Stingray to locate a defendant in a Wisconsin criminal case, United States v. Damian Patrick. Amazingly, the government didn’t disclose this fact to the defendant—or the court—until we raised it in an amicus brief we filed in the case. In the government’s brief, filed late last week, it not only fails to acknowledge the impact of hiding this fact from the defendant but also claims its warrantless real-time location tracking didn’t violate the Fourth Amendment.

We first learned about this case when it was already on appeal to the Seventh Circuit Court of Appeals and filed an amicus brief arguing the Fourth Amendment protects all of us from warrantless, real-time location tracking. The government suggested to both Patrick and the trial court that it had relied on location information obtained directly from Sprint. However, we suspected they had instead used a Stingray.

Stingrays Allow Indiscriminate Dragnet Searches of All Cell Phones in an Area

Stingrays, otherwise known as cell-site simulators, act as a fake cell-phone tower. They can be small enough to fit in a car and allow the government to direct all cell phones in the area to connect to it instead of the real tower. In doing so, the government can get a very precise picture of exactly where those phones are located—much more precise than many other types of location tracking technologies.

Stingrays are especially pernicious surveillance tools because they collect information on every single phone in a given area—not just the suspect’s phone—this means they allow the police to conduct indiscriminate, dragnet searches—in some cases on up to 10,000 phones at one time. They are also able to locate people inside traditionally-protected private spaces like homes, doctors’ offices, or places of worship and can be configured to capture the content of communications.

The Milwaukee Police Department Tried to Hide its Use of a Stingray

In this case, the police first told Patrick they’d relied on “information obtained from an anonymous source” to find him sitting in the passenger seat of a car parked in an alley in Milwaukee.  It wasn’t until six months after his arrest that they revealed they’d tracked him through his cell phone, and even then they implied they’d gotten location information directly from the cell phone service provider. The government never got a search warrant to use any kind of technology to find Patrick in real time.

As we’ve seen in other cases involving Stingrays, the government did everything it could in this case to hide the fact that it used a Stingray—from the court that issued the pen register/trap and trace order, the court that heard Patrick’s motion to suppress the evidence, and even from Patrick, himself. In police reports, the officers said only that they “‘obtained information’ of Patrick’s location; . . . had ‘prior knowledge’ that Patrick was occupying the vehicle; . . . [and] ‘obtained information from an unknown source’ that Patrick was inside the vehicle at that location.” And even at an evidentiary hearing where officers admitted to cellphone tracking, they would only acknowledge, cryptically, that they’d received “electronic information” confirming Patrick was in the vehicle. When Patrick’s attorney asked what “electronic information” meant, the officer on the stand would say only that it involved “tracking [a] cell phone.” The judge cut off any further questioning at that point.

Luckily, in our amicus brief we were able to point the court to Milwaukee Police Department logs showing the police had used a Stingray on the very same day Patrick was arrested, under strikingly similar circumstances.1 We also directed the court to a non-disclosure agreement, which the Milwaukee police signed just months before Patrick was arrested. In this standard FBI-issued NDA, signed by many other state and local agencies across the country, the police department agreed not to tell anyone (even the judge) in any civil or criminal proceeding that it had used a Stingray. It also agreed to dismiss any case—at the FBI’s request—if the court tried to force it to reveal anything about the device.

Once we presented these facts to the appellate court, the government finally admitted it used a Stingray but would not concede this should have any impact on the legal analysis in this case. In a footnote to the brief the government filed last week, it even appeared to blame Patrick for failing to raise this at the trial court.

The Government Admits it Needs a Probable Cause Warrant to Conduct Real-Time Location Tracking

Interestingly, even though the government doesn’t think it’s secret use of a Stingray impacts this case, it admits that using technology to track someone’s location in real time (whether through location information obtained from the phone company or by using a Stingray) is a “search” for Fourth Amendment purposes. It also admits it needs probable cause and a search warrant to legally execute such a search. This appears to be the first time the government has admitted these things in an appellate case.

But the government also argues it didn’t violate the Fourth Amendment in this case because it actually got a warrant—or maybe, in the alternative, the equivalent of a warrant (the police had a warrant to arrest (not search) Patrick and a court order (not a search warrant) to track Patrick’s phone). In a confusing and somewhat circular argument, the government asserts that because it submitted a “sworn affidavit” in support of its request for the pen/trap order, the order must have actually been a search warrant—if it hadn’t been a warrant, then it “wouldn’t have needed a finding of probable cause, which it contained.”

The Seventh Circuit Should Follow Maryland and Find Secret, Warrantless Stingray Use Unconstitutional

It’s now up to the Seventh Circuit to try to make sense of this argument (or maybe just to send the case back to the trial court for a new trial). If the appellate court decides to take this issue on, we hope it follows a recent Maryland appellate decision, State of Maryland v. Andrews (another case where we were amicus), where the court held unanimously that the Baltimore Police Department’s very similar secretive behavior and failure to get a search warrant before using a Stingray violated the defendant’s constitutional rights. Andrews is the first appellate decision that we know of where a court has ever looked at police use of a Stingray. We hope it sets a very persuasive precedent to all courts that secret, warrantless Stingray use violates the Fourth Amendment.

• 1. Huge thanks to privacy advocate and EFF friend Mike Katz-Lacabe for obtaining this information under Wisconsin’s public records statutes and sharing it with EFF and ACLU!