Can Police Track Your Location? Minnesota Supreme Court Rules on Geofence Warrants
Short answer: yes. Longer answer: how they obtain a warrant matters, and the Fourth Amendment places limits on their ability to do so. In today’s age, we are perpetually tracked. And, the most common tracking device is your cell phone. In law enforcement investigations, especially the who-done-it type, such as your friendly neighborhood murder, the police want to know where your cell phone was at the time of the incident. Because cell phones are now a human appendage, track the cell phone, track the person.
What is a Geofence Warrant?
Tracking location data via a search warrant has a fancy name: geofence warrant. A geofence warrant allows law enforcement to request location data from a technology company for devices located within a defined geographic area during a specified period of time. The police may not know whose devices they are searching for, which is the whole point. For those interested in privacy, and who did not commit a murder, what could go wrong? The Fourth Amendment to the United States Constitution and Article I, Section 10, of the Minnesota Constitution both protect against unreasonable searches and seizures. Granting government tracking location data from a cell phone is a search. The problem is a geofence warrant can sweep up location information belonging to people who have absolutely nothing to do with the crime being investigated. Which raises an important constitutional question: how much information can the government obtain about innocent people while investigating someone else? Requiring law enforcement to narrow its scope of the search with a warrant is where appellate courts are starting to do their work.
State v. Contreras-Sanchez: How Police Used a Geofence Warrant
This past spring, in State v. Contreras-Sanchez, the Minnesota Supreme Court tackled the constitutionality of geofence warrants. In Contreras-Sanchez, Google supplied devices IDs to law enforcement, so they could decide which devices were relevant. The cops were looking for data connecting Contreras-Sanchez to an intentional murder occurring in a specified area. Specifically, a rectangular perimeter of 65 feet by 290 feet, which encompassed an area near a public road and a portion of a ditch. At the time, law enforcement had a body, determined it was a homicide, but did not know the cause of death at the time. The cops applied for, and received, a geofence warrant. After Google said the search time frame was too vast, the police narrowed the time frame, which produced twelve devices within the geofence within one of the specified times. One device hit more than others and was in a specific area for ten minutes. The police then asked Google for step-two location data on that specific device without first asking for a warrant. That data produced a location near a gas station that had surveillance video, which law enforcement reviewed and saw four persons of interest. Then, the police asked for another warrant to ask Google for identification information for the device in interest, so they could find out whose cell phone it was. That came back as Contreras-Sanchez.
Why Did the Minnesota Supreme Court Find the Geofence Warrant Unconstitutional?
The Minnesota Supreme Court did not determine that geofence warrants are per se unreasonable. In fact, it acknowledged “geofence warrants are a useful tool for law enforcement. The problem the Minnesota Supreme Court had was officers did not return to a judge for an additional warrant after getting the initial information from Google about which devices hit in its geofence. It reasoned the initial geofence warrant was supported by probable cause. And, importantly, the police did not need probable cause to believe every person whose device appeared within the geofence committed a crime. The problem was what happened next. The warrant allowed officers to decide for themselves which devices deserved further investigation and then demand additional location data extending beyond the original geographic boundaries and time frame. Without a judge reviewing that expanded search, the police had too much discretion. Which is exactly what the particularity requirement is designed to prevent. The court wrote “had there been judicial review of the reasonableness of that expanded search, the result here may have been different.” The supreme court reversed the court of appeals and remanded for consideration on the merits of the issues it did not reach. It did not vacate Contreras-Sanchez’s conviction. It merely sent the case back to the court of appeals to address the good-faith exception and harmless error arguments not reviewed since it determined the warrant was valid originally.
It appears the Minnesota Supreme Court is taking a careful approach to curtailing a useful tool for law enforcement that also can provide location data on entirely innocent citizens. The Minnesota Supreme Court also decided it was important enough to get its opinion out in April of this year while Chatrie v. United States was pending before the United States Supreme Court. In Chatrie, the U.S. Supreme Court determined obtaining a person’s Google location-history data is a search under the Fourth Amendment. But the court did not decide whether the particularly geofence warrant was valid. It remanded to the lower court to address probable cause and particularity at each stage. Both decisions held geofence warrants are constitutional. But both recognize meaningful limits on the government’s ability to obtain cell phone tracking data.
What Does This Mean for Cell Phone Privacy in Minnesota?
What does this mean for someone charged with a crime where the police obtained cell phone location data? Primarily, it means that even if the cops obtained a warrant to get the location data, does not make the evidence automatically admissible in court. The warrant still needs to comply with constitutional requirements in Minnesota and at the federal level, including probable cause and particularity. If the cops obtained information beyond the scope of their warrant, or if their warrant was insufficient in the first place, then the defense attorney may file a motion to suppress the evidence. Whether the evidence ultimately gets thrown out is up to the district court judge, and potentially appellate judges as well. As Contreras-Sanchez demonstrates, even an unconstitutional search does not automatically mean a conviction gets overturned.
Robert H. Ambrose is a criminal defense attorney representing clients in Minnesota and Wisconsin, with offices in Woodbury and Minneapolis. He is also licensed to practice in federal court, has been recognized by Super Lawyers for the past five years, serves as an adjunct professor at the University of Minnesota Law School.