Court rules geofence warrant violates Fourth Amendment

A California trial court has held a geofence warrant issued to the San Francisco Police Department violated the Fourth Amendment and California’s landmark electronic communications privacy law, CalECPA. The court suppressed evidence stemming from the warrant, becoming the first court in California to do so. EFF filed an amicus brief early on in the case, arguing geofence warrants are unconstitutional.

The case is People v. Dawes and involved a 2018 burglary in a residential neighborhood. Private surveillance cameras recorded the burglary, but the suspects were difficult to identify from the footage. Police didn’t have a suspect so they turned to a surveillance tool we’ve written quite a bit about—a geofence warrant.

Unlike traditional warrants for electronic records, a geofence warrant doesn’t start with a suspect or even an 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 link at all to the crime under investigation. Google has said that for each warrant, it must search its entire database of users’ location history information. Geofence warrants are problematic because they allow police access to individuals' sensitive location data that can reveal private information about people's lives. Police have also used geofence warrants during public protests, threatening protesters' free speech rights.

In Dawes, the court rejected the SFPD’s geofence warrant. The court held the defendant had a reasonable expectation of privacy in his locational data under CalECPA (the California Electronic Communications Privacy Act, which governs warrant requirements for state law enforcement accessing electronic information) and that the warrant did not satisfy the probable cause and particularity requirements of the Fourth Amendment. Although the court found the time period requested by SFPD—2.5 hours—was reasonable given the evidence, it held the warrant was overbroad because the size of the designated geographic area—which covered the burgled home and the entire street traveled by the suspect—was too large. The court stated: “(t)his deficiency in the warrant is critical because the geofence intruded upon a residential neighborhood and included, within the geofence, innocent people's 13 homes who were not suspected to have any involvement in the burglary, either as a suspect, victim or witness."

https://www.eff.org/deeplinks/2022/10/california-court-suppresses-evidence-overbroad-geofence-warrant

See also:
Privacy advocates fear Google will be used to prosecute abortion seekers (Using similar geofence warrants)

https://www.npr.org/2022/07/11/1110391316/google-data-abortion-prosecutions