In a decision today, the Supreme Court said it would hear arguments on law enforcement’s controversial use of historical cell tower location data, in a case that may have major privacy law implications.

The case centers around a practice that allows police to gather historical cellphone location information without a warrant, by instead invoking a controversial statute called the Stored Communications Act. Telecommunications companies provide law enforcement with location data that can reveal where a person’s mobile device was at a given time, which civil liberties groups argue infringes on the Fourth Amendment. In the case the court agreed to hear, a robbery suspect was convicted after obtaining months of records showing nearly 13,000 location data points.

“The question at the center of this case — whether there is a reasonable expectation of privacy under the Fourth Amendment in a person’s cell site location information held by their cellular service provider — requires definitive resolution by this Court,” the ACLU said in its petition to the court. Other, lower courts, the ACLU noted, have sought guidance on the issue.

Much of the debate focuses on how previous court rulings should be applied in the digital age. A legal theory known as third-party doctrine, which argues there is no reasonable expectation of privacy when a citizen gives their data to a third party, is often cited in similar cases, and has been used to decide the cell site issue. But whether the theory still holds in an age where so much personal information is digitally stored by third parties, or whether a new theory is needed, is now the question in front of the court.