In a 5-to-4 decision, the Supreme Court on Friday ruled that the government generally does need to obtain a warrant before collecting location data from cell phones.

The case, Carpenter v. United States, posed a question that has come up time and again – do police need a warrant based on probable cause before accessing cell phone location records from wireless carriers? The Supreme Court said yes, but stressed that its decision is narrow.

"We hold only that a warrant is required in the rare case where the suspect has a legitimate privacy interest in records held by a third party," Chief Justice John Roberts wrote, according to The New York Times.

Privacy advocates are now celebrating what they're calling a landmark victory.

Today's historic Supreme Court cellphone tracking win will have a ripple effect for privacy. It will help protect all sorts of digital information stored online, from emails to data from smart home appliances. — ACLU (@ACLU) June 22, 2018

The American Civil Liberties Union (ACLU) represented Timothy Carpenter, who was convicted of robbery in Detroit, based in part on months' worth of phone location records the government obtained in 2011 without a probable cause warrant. The records covered 127 days, revealing 12,898 separate points of location data.

The ACLU argued that because cell phone location records offer a wealth of private details about people's lives — such as their personal relationships, visits to the doctor, or religious practices — they should be covered by the Fourth Amendment, which protects against "unreasonable" searches and seizures by law enforcement.

Tech giants including Apple, Facebook, Google, Twitter and Verizon in August filed a brief with the Supreme Court arguing that the Fourth Amendment "must adapt to the changing realities of the digital era."

The decision comes after the 4th US Circuit Court of Appeals in Richmond, Virginia, ruled in 2016 that law-enforcement officials do not need to obtain a warrant before tracking a person's location via wireless carriers. The court found that location data is already delivered to a third party—in this case, the carriers—and therefore doesn't require a warrant if data is readily accessible.