Geofencing Warrants Are a Threat to Privacy Google initially listed 5,723 devices in response to the warrant, then whittled the tally to exclude likely Capitol staff and police as well as anyone who wasn't "entirely within the geofence, to about a 70 percent probability." The final list of identifying details handed over to the FBI had 1,535 names. It included people whose phones had been turned off or put in airplane mode, and "people who attempted to delete their location data following the attacks were singled out by the FBI for greater scrutiny.
In about 50 cases, Wired notes, "geofence data seems to have provided the initial identification of suspected rioters." Rhine is technically not among them—the FBI got a tip he'd been at the attack—but it was only through the geofencing warrant that agents were able to find surveillance footage showing him inside the building.
And that gets us to what's troubling here: The Fourth Amendment requires search warrants to specify "probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized." A geofencing warrant arguably allows law enforcement to work backward, to say, We think a crime was committed around this place and this time. Let's sweep up location data for everyone who was there and investigate them all.
https://reason.com/2022/12/05/geofen...at-to-privacy/