These so-called "reverse warrants" first started coming to light earlier this year. The Raleigh Police Department (NC) was serving warrants to Google in hopes of figuring out who to suspect of committing crimes, rather than having a suspect in mind and working forward from there. The warrants were of the "general" variety, guaranteed to give the RPD location/identifying info of hundreds of non-suspects who just happened to be in the area. There's some evidence Google has pushed back against these warrants, but it hasn't been enough to deter law enforcement from continuing to use Google as one-stop shopping to bulk location/identifying info.

This practice isn't limited to the local boys. Thomas Brewster of Forbes has obtained a warrant[PDF] showing the FBI is doing the same thing.

The most recent order on Google, unearthed by Forbes earlier this week, came from the FBI in Henrico, Virginia. They went to Google after four separate robberies in which unidentified, armed individuals entered and stole from the same Dollar Tree store between March and September this year. The manager of the Dollar Tree was also robbed at gunpoint while dropping off money at a Wells Fargo night-deposit box located just down the road from the store.

The warrant asks for location histories held by Google for anyone within three separate areas—including regions around the Dollar Tree store and the Wells Fargo address—during the times and days the five robberies took place. The FBI also wanted identifying information of Google account holders in those areas, two of which had a 375-meter radius. The other had a 300-meter radius.

Since Dollar Tree stores are never found thousands of feet away from other businesses and residences, the information demanded of Google would include hundreds or thousands of innocent people who live or work near the targeted store.

This isn't the way warrants work. Or, at least, this isn't how they're supposed to work. Unfortunately, the FBI's stated probable cause for demanding this info isn't attached to the document Forbes obtained, so it's unclear how the FBI talked a judge into signing off on this. What the returned warrant does show is no records were returned, suggesting Google is pushing back against broad requests for data that appear to be unsupported by probable cause.

While this may be the digital equivalent of canvassing nearby businesses and residences to search for suspects, these orders make compliance compulsory by eliminating the citizenry. It appears the government believes the combination of warrants and third-party data makes gathering info on hundreds or thousands of non-suspects constitutional. The FBI's warrant also came with an indefinite gag order, so no one included in the search radius had any idea federal law enforcement wanted to know who they were or where they'd been.

This search tactic will continue to be deployed until a court puts an end to it. Without more data, it's hard to say how often magistrates approve or reject these reverse warrants. All we know is somewarrants have been approved. And in some cases, Google has refused to provide the data. I'm sure law enforcement knows these demands for data aren't completely constitutional, which may be why we haven't seen any agency bring Google to court for refusing to comply. Additional judicial scrutiny isn't going to do these warrants any favors.