Orwell described a world where limitless surveillance makes us question every action, every thought. Last Friday’s decision in Carpenter v. United States brought us one step back from the brink of realizing his dystopian vision, curtailing law enforcement’s growing use of warrantless location tracking, but the Court’s ruling makes clear that the debate is far from over. As the law struggles to keep pace with the growth of cheap, powerful, and prolific tracking tools, Carpenter marks a crucial step away from formalistic privacy analysis that hobbled prior Fourth Amendment cases.

Carpenter examined a question that would have been science fiction just a few years ago: can law enforcement turn our own property into government tracking devices. Of course, our cellphones have now made this type of tracking mundane, an everyday part of staying connected to the digital world. The government didn’t need a bug or a GPS tracker to keep tabs on Carpenter’s movements, they could simply pull a log of his wireless carrier’s cell site location information(CSLI), providing a record of where his cellphone had been. As long as a phone is turned-on, it continually pings the nearest cell tower, enabling the cell network to know where to route any incoming calls.

The technology isn’t always precise. Depending on the size of the area served by a cell tower, CSLI could reveal a device’s location with the precision of anywhere from a few square miles to 50 square feet. But the technology is only improving, and it’s likely (as the Court noted) that CSLI could mirror the accuracy of GPS tracking in the near future.

In 2012, the Supreme Court addressed a similar technique in United States v. Jones, ruling that it was unconstitutional for law enforcement to attach a GPS tracking device to a vehicle without a warrant. The Court was unanimous in striking-down the tracker, but the justices were split on the rationale. Justice Scalia’s decision for the Court was based on the car-owner’s right against trespass, the violation when agents physically attached the GPS device. Crucially, unlike in Jones, CSLI data collection doesn’t require agents to physically touch a target’s phone. Like an increasing amount of surveillance, it only requires law enforcement to access data held by a third party.

Prior to Friday’s decision, law enforcement officials felt free to suck-up nearly limitless amounts of CSLI data without a warrant. To request these records, they would simply obtain an order under 18 U.S.C. § 2703(d) (a “D Order”) by showing reasonable grounds to believe the records are “relevant and material to an ongoing criminal investigation.” This is a much lower standard than what is needed for a warrant, explaining why in 2016 alone, Verizon and AT&T received approximately 125,000 requests for CSLI data. Such a low standard opened the door for a virtual big brother to reconstruct the movements of nearly any American.

Alarmingly, we came within just one vote of the decision going the opposite way, with four justices dissenting that CSLI data doesn’t require a warrant. Even Justice Kennedy wrote separately to argue that under the Third Party Doctrine, law enforcement should have free-reign to request any information Americans share with businesses (such as our banks, telecom providers, etc.). This rule might have made sense in a prior age, but it’s hardly understandable how any meaningful conception of privacy would survive a world where law enforcement could simply sap-up our data from health trackers, cloud storage, or electronic assistants.

Unfortunately, the Carpenter decision didn’t go far enough, and the justices refused to address how their ruling would impact other highly sensitive types of data. Rather than jettisoning the Third Party Doctrine altogether, the Court simply carved-out CSLI, finding that the records were not really shared with carriers. They recognized that cellphones have become a necessity of modern life; opting-out of owning a phone would require one to opt out of much of modern life.  Also, the Court noted that users are not meaningfully consenting to share the data provided through CSLI. In fact, most users don’t even know that there CSLI information is being obtained, let alone that it can be shared with law enforcement and other third parties.

The question now becomes how far the Court will apply this recognition that privacy transcends property rights. And the question doesn’t just extend to the FBI. Here, in New York, it’s easy to see how the Justices could find similar privacy concerns regarding many of the tools that NYPD uses to monitor New Yorkers. The most direct comparison is the broad and growing network of license plate readers (LPRs) that are deployed on bridges, tunnels, and other locations throughout the city. These cameras can record dozens of cars per minute, tracking vehicle location in real time. While we haven’t yet reached the point that LPRs are as ubiquitous as cellphones, the technology will only get cheaper, and it’s easy to imagine NYPD eventually integrating the technology into ordinary office building security cameras (which are already linked to the City under its Domain Awareness System).

My organization, CAIR-NY, and other police reform advocates have pushed for years to improve oversight of these technologies, pushing legislation at the state and local level. Bills like the Public Oversight of Surveillance Technology (POST) Act would create transparency and reporting requirements for the NYPD’s use of surveillance technology. As things stand, oversight is so non-existent that lawmakers don’t even know what spy gear the NYPD is buying, let alone what steps its taking to keep the information it collects safe. For a self-described “sanctuary city” like New York, this oversight is indispensable, as reports have already confirmed that LPR data is being shared with U.S. Immigration and Customs Enforcement. For many New Yorkers, its indefensible that our city’s resources are being used to help deport immigrant New Yorkers.

These local and state reform efforts will certainly continue, but in the wake of Carpenter, advocates and attorneys have new hope that a reinvigorated Fourth Amendment will provide some of the protections that our lawmakers have failed to implement. That said, the ruling is just the start, it remains to be seen how far the Justices will go in making sure our laws and privacy protections keep pace with emerging technology.

At the time of writing, Albert Cahn was Legal Director of the New York Chapter of the Council on American-Islamic Relations, and Karin Bashir was a rising 2L at U.C. Berkeley’s Boalt School of Law.

Image: Justin Sullivan/Getty