The Supreme Court on Monday ruled that when law enforcement used what's called a "geofence warrant" to obtain evidence to convict a man in a 2019 bank robbery case, they conducted a search under the Fourth Amendment. The 6-3 ruling sends the case back to lower court for it to consider if the search was "reasonable," as the Fourth Amendment requires.

Under a geofence warrant, law enforcement accesses cellphone data from a company in a location during a specific time period.

Writing for the majority, Justice Elena Kagan said that an "individual has a reasonable expectation of privacy in records about his cell phone’s location, and police intrude on that constitutionally protected interest when they demand the information—even though for only a limited time, and from a third-party tech company."

Monday's ruling stemmed from a case in which a man was alleged to have entered a federal credit union outside Richmond, Virginia, armed with a gun, according to SCOTUSBlog. He gave the teller a note demanding money and ran off with $200,000, according to prosecutors. 

In trying to get a lead in the case, law enforcement served Google with a geofence warrant, which granted them access to cellphone data near the bank around the time of the robbery. After repeated requests for more information, police narrowed the search down to an account held by Okello Chatrie.Chatrie pleaded guilty to bank robbery but retained his right to appeal. He was sentenced to 12 years, followed by three years of supervised release. 

The U.S. Court of Appeals for the Fourth Circuit upheld the denial of Chatrie's motion to suppress the evidence.