On October 13, 2018, two men entered a Great Midwest Bank in a suburb strip mall outside of Milwaukee. They were the first two customers when the bank opened, barely recognizable behind sunglasses and heavy beards – but it soon became clear what they were looking for. A man jumped on the counter and pulled out a gun and threw away a garbage bag for the storytellers to fill with money. They left the bank at 9:09 am, just seven minutes after they came in, with the bag full of money, three drawers from the safe and counter and the keys to the bank safe itself.
In the following months, police and federal agents have difficulty tracing bank robbers. Local media sent photos from the security camera & # 39; s from the bank, but it did not produce leads. Finally, the police took a more aggressive strategy: ask Google to track down the bank robbers' phones.
Agents served Google in November a search warrant, requesting data that could identify any Google user who was within a 30-meter radius of the bank within a 30-hour period of the robbery. They searched for the two men who had gone to the bank, as well as for the driver who dropped out and picked up the crew, and might end up in the same dragnet. It was an aggressive technique, where every Android phone in the area was picked up and the police were trusted to find the right suspects in the mess of resulting data. But the court found it completely legal and it was sent back shortly thereafter.
That kind of warrant, better known as searching in reverse locations, has become more common in recent years. More than 20 such warrants have been served in Minnesota, and at least one similar case has come to light in North Carolina. The technology was most controversial used to identify suspects after a Prally Boy rally-turn-riot in Midtown Manhattan last year.
In any case, the police did not track the location of a specific suspect – where normal standards of reasonable suspicion would apply – but instead drew the names of every person who had been around when a crime took place. For groups of civil liberties, it is a dangerous and possibly unconstitutional scope of police force. But those concerns have not been sufficient to prevent the police from submitting reverse search warrants when a case runs dry, or to convince judges to reject them.
In the case of Wisconsin, it is not clear how useful that technique actually was. When The edge extended to the Milwaukee Division of the FBI to ask if any charges had been filed. With nearly a year since the order was issued, this suggests that this specific reverse location search might not have been as fruitful as researchers had hoped.
Groups such as EFF have many problems with this type of search, in particular that it goes against a precedent of the Supreme Court that treats location data as "an intimate window in a person's life." But the biggest problem is the simple success rate: in the case of Wisconsin, the police asked for a dragnet that could produce that sensitive location data for dozens of people – but if the bank robbers didn't use Google Maps or just left their phones at home, they would do not appear in that search query. For civil libertarians, that looks like a lot of suspicious searches and nothing to show for it.