Sitting en banc and reversing a majority panel decision, the Fourth Circuit in US v. Graham held that a cell phone’s CSLI (cell site location information) or communications with nearby cell towers (the assumption is that the cell phone is communicating with the closest tower to it but that may not always be the nearest available tower), placing the cell phone within appx. 4 square miles of one of the cell tower’s three sectors, falls under the “third party doctrine”: that one assumes the risk that information given to another , especially in the normal course of doing business with the third party, will not remain private. Legally, this entails that no invasion of privacy–as contemplated by the Fourth Amendment–takes place if the Government obtains that information from the cellular provider even without a search warrant supported by a showing of probable cause that criminal activity is taking place. In this case, the CSLI was used to convict individuals of federal robbery charges by placing the defendants in the vicinities of the robberies around the time of the crimes.
Thus, the Fourth Circuit treats CSLI as non-content information (like IP addresses, to/from addresses in emails, routing info, etc) under the Stored Communications Act (which is under the broader umbrella of the Electronic Communications Privacy Act), which allows federal (and state) law enforcement officials to obtain that non-content information through a court order supported by merely reasonable suspicion rather than probable cause that criminal activity is afoot. According to the Fourth Circuit, this statute, as applied to even the weighty privacy interests implicated by CSLI (the long term tracking of movements even in public can reveal a great deal of private information about a person), does not offend the Fourth Amendment.
Historic CSLI was distinguished, however, from real time GPS information that tracks the precise location of someone, especially into historically protected private spheres, like one’s home. Thus, it appears that the Fourth Circuit would require federal law enforcement agencies to obtain a warrant supported by probable cause for that information. The court emphasized that CSLI is generated by the cell provider in the normal course of business, and suggested that the Government engaging in surreptitious surveillance through tools outside the normal course of a cell provider’s business — like Sting Rays (they mimic cell towers and suck up info about nearby cell phones) or forcing a cell provider to conscript a cell phone’s E-911 system in order to turn the device into a real time GPS tracker–indeed fall outside the third party doctrine and, therefore, require a warrant supported by probable cause.
The court recognized, as the Supreme Court noted in Jones concurring opinion, that the third party doctrine may be ill suited for the digital age, but that issue is for either the Supreme Court or for Congress to take up (whether CSLI records requires a search warrant under the Fourth Amendment is an issue that needs to be preserved for appeal given the likelihood of SCOTUS taking up this issue on day). The court noted the weighty privacy concerns with CSLI do give rise to arguments that the Fourth Amendment needs to be modernized, especially in the era of “cloud” computing (use of remote servers to store even sensitive data), otherwise one will have to opt out of modern society and live off grid in order to preserve privacy protection under the Fourth Amendment, an outcome, to borrow the Fourth Circuit’s own words, is “untenable in the abstract and bizarre in practice.”