The Supreme Court is going to take a look at the Fourth Amendment implications of warrantless access to historic cell site location information. The outlook for a Fourth Amendment win isn't particularly hopeful, given that there's no circuit split to be resolved. The lone holdout was the Fourth Circuit -- which originally had problems with the long-term collection of location information -- but that court reversed its earlier decision to align with other circuits which have addressed the issue.
That doesn't mean no one should try! Who knows what the court might decide, especially given the shifting telecommunications landscape. After all, it has managed to budge the 4th a wee bit now and then, even in decisions that were mostly punts or calls for the aggrieved to take it up with their Congressional reps.
The ACLU has filed a brief [PDF] on behalf of the appellants, pointing out what should be obvious: cell site location info isn't Just Another Third Party Record. It's a proxy tracking system for law enforcement, which can access this data without warrants. And it's only getting more precise every day.
Service providers have long retained location information for the start and end of incoming and outgoing calls. Today, those companies increasingly also retain location information related to the transmission of text messages and routine internet connections—which smartphones make virtually constantly to check for new emails, social media messages, weather updates, and other functions. The information recorded can include not only cell site and sector, but also estimated distance of the phone from the nearest cell site. Id. Location precision is also increasing as service providers deploy millions of “small cells,” “which cover a very specific area, such as one floor of a building, the waiting room of an office, or a single home.” United States v. Graham, 824 F.3d 421, 448 (4th Cir. 2016) (en banc) (Wynn, J., dissenting in part and concurring in the judgment) (citation omitted); see also Hoy, supra, at 69-70. All told, a typical smartphone connects to cell towers hundreds of times a day, generating a densely pixelated matrix of data points documenting the user’s movements. The volume and precision of that data will grow steadily in coming years, generating ever more granular locational information.
The ACLU notes Congress itself has granted consumer protections for CSLI, giving customers control over who has access to this data. Unfortunately, multiple courts have ruled that, since cell providers have access to the info and customers are at least somewhat aware their phones must connect to towers to provide service, this information can be obtained by the government with only a subpoena. (And, obviously, without the customer's consent.) In some rulings, this has been extended to real-time location tracking, with law enforcement officers basically shoulder-surfing telco computers for pings.
The brief draws a connection between virtual location tracking with CSLI and the Supreme Court's Jones decision, which dealt with long-term tracking of individuals with concealed GPS tracking devices. That decision didn't quite establish a warrant requirement, but did suggest warrantless long-term location tracking raised a number of Fourth Amendment issues.
Allowing law enforcement agencies to use service providers as tracking devices is a problem. It shouldn't really make a difference whether it's long-term or short-term, but the tremendous amount of location data automatically gathered can provide an extremely in-depth examination of someone's life, all through the magic of third-party records.
Worse, long-term tracking through CSLI exposes even more of a person's movements to the government. Phones go places cars don't. A suspect could "opt out" of GPS data collection by walking, using public transportation, or riding in vehicles without tracking devices. But people's phones go everywhere they go. Having this wealth of information on tap is a boon for law enforcement. Obtaining a warrant isn't some sort of insurmountable obstacle. The world has changed incredibly since 1979, which is when the Supreme Court created the Third Party Doctrine out of thin air. If nothing else, this case should give it the opportunity to take another look at a decision headed into its fourth decade and see if it still remains relevant in a world where almost every citizen carries around a proxy government tracking device wherever they go.