In January 2020, Zachary McCoy of Florida received a concerning email from Google: local authorities were asking the company for his personal information and he had just seven days to stop them from handing it over, the Guardian reports. Police were investigating a burglary and had issued to Google what’s called a geofence warrant. The court-ordered warrant requested the company look for and hand over information on all the devices that were within the vicinity of the broken-into home at the time of the crime. McCoy was on one of his regular bike rides around the neighborhood at the time and the data Google handed over to police placed him near the scene of the burglary. McCoy was in the wrong place at the wrong time – and he had now become a suspect of a crime he did not commit.
This was not an isolated incident. From Virginia to Florida, law enforcement are increasingly using tools called reverse search warrants – including geofence location warrants and keyword search warrants – to come up with a list of suspects who may have committed particular crimes. While the former is used by law enforcement to get tech companies to identify all the devices that were near a certain place at a certain time, the latter is used to get information on everyone who’s searched for a particular keyword or phrase. It's a practice public defenders, privacy advocates and many lawmakers have criticized, arguing it violates Fourth Amendment protections against unreasonable searches. Unlike reverse search warrants, other warrants and subpoenas target a specific person that law enforcement has established there is probable cause to believe has committed a specific crime. Geofence warrants are sweeping and are often used to compile a suspect list.