As worshippers gathered in 2020 at the Calvary Chapel in San Jose, California, they were being watched from above.
Satellites were locking in on cell phones owned by members of the nondenominational Protestant church. Their location eventually worked its way to a private company, which then sold the information to the government of Santa Clara County.
This data, along with observations from enforcement officers on the ground, was used to levy heavy fines against the church for violating COVID-19 restrictions regarding public gatherings.
“Every Sunday,” Calvary’s assistant pastor, Carson Atherly, would later testify, the officers “would serve me a notice of violation during or after church service.”
Calvary is suing the county for its use of location data, a controversial tool increasingly deployed by governments at all levels—notably in relation to the U.S. Capitol breach on Jan. 6, 2021. While enabling law enforcement to more easily identify potential offenders, the practice, called “geofencing,” has also emerged as a cutting-edge privacy issue, raising constitutional issues involving warrantless searches and, with Calvary Chapel, religious liberty.
“We are in the space between the emergence of this technological practice and courts having ruled on its constitutionality,” said Alex Marthews, national chair for Restore the Fourth, a nonprofit organization dedicated to the protection of the Fourth Amendment, which protects Americans’ rights against “unreasonable search and seizure.”
While it’s legal for private companies to broker this information, constitutional questions arise when the government accesses data from a third party that it would be prohibited from collecting on its own. The lawsuit filed by Calvary Chapel argues that Santa Clara County carried out a warrantless surveillance of the church when it acquired information in 2020 on the church’s foot-traffic patterns for analysis by a research team from Stanford University.
Court documents show that the researchers acquired the information, which originated with Google Maps, from the location data company SafeGraph, which Calvary is also suing.
Geofencing allows users to build a fence around certain areas or points of interest such as Calvary Chapel or the area near the Capitol on Jan. 6 and see when people entered that space.
Data brokers, including SafeGraph, insist that their information is anonymized. But it’s precisely the lack of specificity that worries critics.
“There’s no particular individual who the government is suspicious of,” Adam Schwartz of the Electronic Frontier Foundation told RealClearInvestigations. “It’s a dragnet.”
Moreover, there’s no guarantee that the data collected through geofencing stays anonymous.
“It is often very easy to take supposedly de-identified data and re-identify a person,” Mr. Schwartz said. “And it’s very, very easy to do that with location data.”
At Calvary Chapel, for example, in-person surveillance conducted by the county, as well as numerous in-person depositions of Chapel members and employees during the previous legal contretemps between the county and the church that began in 2020, would have provided local officials with detailed knowledge of who was on the premises, and when.
In any event, critics say, law enforcement’s use of geofencing—even when it is backed by a warrant—violates the Fourth Amendment.
Geofencing proponents argue that it falls under the “administrative search” exception to the Fourth Amendment, which lets regulatory enforcement personnel conduct warrantless searches when the greater good is at issue (i.e., at police sobriety checkpoints and airport TSA scans).
In their complaint, Calvary Chapel attorneys assert that the county is arguing in effect “that, as long as they call it research, any level of government can target and spy on any individual or group at any time for any duration and, if they so choose, they can wield the collected data against said individuals or groups who oppose their orders.”
