Tech giant Google is at the center of the FBI’s largest use of a controversial form of search warrants that the federal law enforcement agency used to identify thousands of individuals inside and around the U.S. Capitol on January 6, 2021.

Leveraging Google’s constellation of data points in its location history technology on mobile phone devices, the government is able to place these devices with pinpoint accuracy. Combining GPS coordinates, Wi-Fi, and even Bluetooth accessibility, investigators can incredibly place a phone within a few yards.

In comparison, search warrants issued to phone companies that utilize cell tower infrastructure to triangulate a device’s location are only accurate within three-quarters of a mile.

Often referred to as a “dragnet” search, these geofence search warrants work by targeting a specific geographical place during a certain time frame. All devices that ping a location history meeting those parameters are then given over to the police.

While Google received over 11,000 of these so-called “geofence” search warrants in 2020 from law enforcement across the country, their use by the FBI in the January 6 investigation is without public precedent.

Since geofence search warrants have exploded onto the scene, their use has raised serious privacy questions for the public.

“There’s always collateral damage,” said Jake Laperruque, senior policy counsel for the Constitution Project at the nonprofit Project on Government Oversight. He went on to explain that due to their inherently broad scope, these types of warrants expose people who have committed no criminal activity to police scrutiny.

The use of geofence warrants has ballooned by well over 1,100% since 2018, when law enforcement nationally only requested 941 geofence search warrants from Google.

Possibly even more alarming is that a recent court filing on January 6 of defendant David Rhine’s case suggests that even phones set to “airplane mode” can be identified through a geofence search warrant.

Furthermore, records show that individuals who took the steps to delete their location history on their devices were still identified and then received higher scrutiny by the FBI in its investigations.

For its part, Google has vigorously defended its willingness to hand over data to law enforcement, which may include individuals who have committed no crime whatsoever, according to a statement on geofence search warrants.

“We have a rigorous process for geofence warrants that is designed to protect the privacy of our users while supporting the important work of law enforcement,” Google said. “When Google receives legal demands, we examine them closely for legal validity and constitutional concerns, including overbreadth, consistent with developing case law.”

“If a request asks for too much information, we work to narrow it. We routinely push back on overbroad demands, including overbroad geofence demands, and in some cases, we object to producing any information at all,” the company concluded.

Regarding January 6, the FBI requested all devices within a four-acre area, which included not just the U.S. Capitol but its surroundings, and for between 2 p.m. to 6:30 p.m. that day. It then narrowed that data using a number of other requests from Google to rule out Capitol staffers, police, and other authorized personnel.

Through this process, the FBI identified 1,535 Google users and had maps of their movements in the targeted areas throughout the time window.

The geofence evidence has been cited in over 100 charging documents from January 6 thus far, with more likely to come.

Rhine’s attorneys have made a motion to suppress the geofence evidence against their client, citing privacy and First Amendment concerns.

“The government enlisted Google to search untold millions of unknown accounts in a massive fishing expedition,” his attorneys wrote in the motion. “Just a small amount of Location History can identify individuals … engaged in personal and protected activities (such as exercising their rights under the First Amendment). And as a result, a geofence warrant almost always involves intrusion into constitutionally protected areas.”

What the judge decides will have an extremely profound impact not just on directly related cases but the use of these tactics by law enforcement for the foreseeable future.