SURVEILLANCEEFF Files Amicus Briefs in Two Important Geofence Search Warrant Cases
Unlike traditional warrants for electronic records, a geofence warrant doesn’t start with a particular suspect or even a device or account; instead police request data on every device in a given geographic area during a designated time period, regardless of whether the device owner has any connection to the crime under investigation. The EFF argues these warrants are unconstitutional “general warrants” because they don’t require police to show probable cause to believe any one device was somehow linked to the crime under investigation.
Should the police be able to identify everyone who was in a busy metropolitan area, just because a crime occurred there? In two amicus briefs just filed in appellate courts, we argues that’s a clearly unconstitutional search.[1]
The two cases are People v. Meza, in the California Court of Appeal, and United States v. Chatrie, in the federal Fourth Circuit Court of Appeals. In each case, the defendant is challenging the police use of a surveillance tool we’ve written about before called a “geofence warrant.” In both cases, the lower courts denied motions to suppress. In Chatrie, however, the district court issued a lengthy opinion holding the geofence warrant was unconstitutional before ruling that police relied on the warrant in “good faith” and therefore the evidence from their search was admissible.
Unlike traditional warrants for electronic records, a geofence warrant doesn’t start with a particular suspect or even a device or account; instead police request data on every device in a given geographic area during a designated time period, regardless of whether the device owner has any connection to the crime under investigation. Google has said that for each warrant, it must search its entire database of users’ location history information—data on hundreds of millions of users.
The data Google provides to police in response to a geofence warrant has the potential to be very precise—much more precise than cell site location information, for example. It allows Google to determine where a user was at a given date and time, sometimes to within twenty meters or less. Google can even determine a user’s elevation and establish what floor of a building that user may have been on. As the lower court noted in Chatrie last summer, Google’s database “appears to be the most sweeping, granular, and comprehensive tool—to a significant degree—when it comes to collecting and storing location data.” At the same time, however, Google does not guarantee accuracy. Google’s goal is to accurately infer a user’s location within a certain radius a bare 68% of the time. This creates the possibility of both false positives and false negatives—people could be implicated for a crime when they were nowhere near the scene, or the actual perpetrator might not be included at all in the data Google provides to police.
