Written by: Hannah Huston 

Megan Graham, associate clinical professor and director of the Technology Law Clinic at the University of Iowa College of Law, filed a Supreme Court amicus brief on behalf of herself and 7 other law professors across the country in United States v. Chatrie. She co-drafted the brief with Professors Paul Ohm (Georgetown University Law Center), Jordan Wallace-Wolf (William H. Bowen School of Law at the University of Arkansas – Little Rock), and Brian Owsley (University of North Texas at Dallas).

The case concerns geofence warrants—requests typically made to technology and phone companies for information about all devices in a specific geographic area during a specific time.

Geofence warrants are one type of “reverse search.” As the brief explains, traditional searches require individualized, particularized suspicion before the government can engage in a particular criminal investigative technique. Reverse searches turn this principle on its head by asking for information about many people to subsequently generate a list of potential suspects. With a geofence warrant, law enforcement seeks information about all cell phones that were in a particular area at a particular time, which they then sift through to find phones that are of particular interest. 

Graham and the other professors submitted their brief to help the Supreme Court understand that geofence warrants are just one example of reverse warrants that are in use today or may be soon. The Court’s decision and its reasoning could substantially change our understanding of what sorts of information law enforcement can obtain from private companies about their customers, and what level of suspicion is needed to do so.