The US Supreme Court is hearing arguments about the legality of so-called geofence warrants, sometimes also referred to as “digital dragnets” because they capture the location data of a great many innocent citizens in addition to criminal suspects.
In a practice raising obvious privacy concerns, tech giants are increasingly being asked by law enforcement to identify all of the smartphone users present at a particular location at the time a crime was committed …
CNET explains how geofence warrants work.
If there are no clear suspects for a crime, law enforcement can serve a warrant to a tech giant requesting location data. Police draw a circle on a map around a crime scene and specify a time window. The tech company (most frequently Google) searches its database for devices inside that “fence” during that time. The police can then ask the company for the specific account details — such as email addresses, phone numbers and usernames.
The arguments for and against
While police are supposed to have good reason to suspect those whose details they demand, this may in practice amount to nothing more than being in the general location during the time-frame during which a crime was committed. In one example given of a bank robbery, those deemed to be present at the location included people sitting in a church close to the bank.
The Department of Justice is arguing that smartphone location data should not be classified as “sensitive data” since it represents public movements that others could observe. Additionally, lawyers for the DOJ argue that anyone is free to turn off location services.
Privacy advocates argue that being able to spot someone you know at a location is very different to obtaining the identities of hundreds or even thousands of strangers, and that smartphone users may be relying on location services in Google Maps or Apple Maps to reach their destination. Lawyers opposing geofence warrants argue that they violate Fourth Amendment protections against illegal search.
What happens next?
There are three possibilities, two of which would in practice amount to the same thing.
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