The Supreme Court on Thursday restricted the use of a relatively new law enforcement technique that allows police to tap into giant tech-firm databases to see who was near the scene of a crime.
Writing for the 6-3 majority, Justice Elena Kagan said that the technique, known as geofencing, violates the Fourth Amendment's prohibition against unreasonable searches.
A "geofence warrant" entails drawing a virtual fence around a geographic area where a crime was committed. The government can then seek a warrant to require a tech company to search its data to identify any of its users who were within the geofence at the time of the crime.
This case stems from a robbery in the suburbs of Richmond, Va. A man stole $195,000 from a bank, but after two months, the case had gone cold. That is, until detectives served a warrant on Google, asking for the location information of cellphone users in and around the bank for the hour before and after the crime was committed.
Complying with the warrant, Google initially found the names of 19 people who were in or near the bank, but Google pushed back, ultimately providing the police with the names of just three people whose location data showed they were at the bank. When police went to the home of one of them, they found a pistol matching one seen on security camera footage of the robbery and nearly $100,000 in cash. That man, Okello Chatrie, later confessed and was convicted of the crime.
His attorneys argued in filings to the court that geofence searches violate the Fourth Amendment because they allow the government "to search first and develop suspicions later." The geofence warrants in this case directed Google to search millions of users' location histories, meaning that millions of people were subjected to a search despite never having done anything suspicious.
But the government argued in its filings that because people can choose not to give companies like Google their location data, that data is not constitutionally protected.