When Gavin McInnes—founder of the violent, far-right group The Proud Boys—spoke to a Manhattan Republican club last October, the neighborhood response was less than welcoming. Protesters took to the normally sedate Upper East Side block with chants and spray paint. The Proud Boys responded with fists and kicks. Nearly a year later, as the assault and riot charges against four Proud Boys go to trial, prosecutors revealed that they had turned to an alarming new surveillance tool in this case: a reverse search warrant.
The Manhattan District Attorney's Office admitted it demanded Google hand over account information for all devices used in parts of the Upper East Side. They didn’t do this to find the Proud Boys; they did it to find Antifa members.
Reverse search warrants have been used in other parts of the country, but this is the first time one was disclosed in New York. Unlike a traditional warrant, where law enforcement officials request information on a specific phone or individual, reverse warrants allow law enforcement to target an entire neighborhood. Police and prosecutors create a “geofence”—a map area—and demand information on anyone standing in the zone. This flips the logic of search warrants on its head. Rather than telling service providers the name or phone number of a suspect, reverse search warrants start with the location and work backwards.