Last month, a federal judge in Richmond, Virginia ruled that the use of a geofence warrant to make an arrest in a robbery case was unconstitutional because it violated the Fourth Amendment. Civil liberties advocates have raised concerns about geofence warrants for a long time because they give police data for anyone whose phone was in a given area during a specific timeframe.

The Takeaway speaks with Jennifer Granick, surveillance and cybersecurity counsel with the ACLU Speech, Privacy, and Technology Project, about what this latest ruling means for the use of geofence warrants going forward.