In a landmark decision, the Georgia Supreme Court has ruled that law enforcement must obtain a warrant before they can access navigation, engine, and other data stored in your car’s computer systems.

The court’s ruling is the first time a state Supreme Court has recognized the potential danger to privacy and constitutional rights created by allowing access to car data without judicial oversight.

In the modern era, data collected by your car now provides a treasure trove of information about your daily habits. Your commute, your driving tendencies, cell phone contacts, even your Spotify playlists create an ocean of information that’s collected, “anonymized” and sold to any number of interested parties—ranging from city planners to the marketing sector.

That data also creates a wonderful target for law enforcement and the potential for abuse when judicial oversight is eliminated from the equation. The American Civil Liberties Union (ACLU) has long argued that the Fourth Amendment protects US residents against unjustified access by law enforcement looking for access to this data.

That fight came to a head in Georgia during Mobley v. State. After a double fatality back in 2014, law enforcement used data collected from both vehicles to impose a harsher prison sentence on Victor Lamont Mobley. Thanks to this data, Mobley’s vehicle was found to have been going 97 miles per hour in a 45 mile per hour speed limit zone.

Today that conviction was overturned; the state supreme court ruling that law enforcement’s decision to access this data without first obtaining a warrant constituted an unreasonable search and seizure in violation of the Fourth Amendment of the Constitution.

The Georgia Supreme Court ruling overturns an earlier state Court of Appeals ruling that defended law enforcement’s decision to skip the warrant.

The state of Georgia had tried to claim that downloading vehicle data stored in Mobley’s vehicle without getting a warrant was justified under what is known as the “vehicle exception” to the Fourth Amendment’s warrant requirement.

But the ACLU had long disagreed, pointing out that earlier precedent leaned on by the state applied largely to physical items found in vehicles, and not the myriad of data now collected by modern vehicles. Opening the door to warrantless vehicle searches, the ACLU warned, also opened the door to widespread abuse of this data by law enforcement and the government.

“In an age when our cars are operated via increasingly complex computer systems, it is vital that courts establish strong protections against police accessing sensitive data without a warrant,” ACLU staff attorney Nathan Wessler told Motherboard.

“Without these protections, police could easily access data about how we drive, where we’ve been, who we talk to, and even who rides in our cars, all without judicial oversight,” he said. “Today’s ruling is an important protection for Americans’ privacy in the digital age.”