Federal Appeals Court: Cellphone Tracking Requires a Warrant

Yesterday a federal appeals court took an important step toward reining in government snooping by ruling that law enforcement agencies need a warrant to collect cellphone location data. The case involved a robbery suspect, Quartavious Davis, who was linked to various crime scenes through data obtained from his cellphone company. The U.S. Court of Appeals for the 11th Circuit concluded that "cell site location information is within the subscriber's reasonable expectation of privacy" and "the obtaining of that data without a warrant is a Fourth Amendment violation."

The decision, U.S. v. Davis, is the first time an appeals court has directly addressed the issue of cellphone tracking in the context of a criminal prosecution, which helps explain why Davis did not succeed in suppressing the evidence against him. The appeals court ruled that the prosecution's use of his cellphone records was covered by the "good faith" exception to the exclusionary rule.

The FBI obtained Davis' records through a court order authorized by the Stored Communications Act, which requires only "reasonable grounds to believe" that the iinformation sought is "relevant and material to an ongoing criminal investigation." A warrant, by contrast, requires "probable cause" to believe that a search will discover evidence of a crime. In deciding that the higher standard is appropriate for cellphone location data, the 11th Circuit relied on the "privacy theory" of the Fourth Amendment, which holds that the constitutional ban on unreasonable searches extends beyond evidence collection that intrudes on the target's property. Since 1967 the Supreme Court has used that theory to require warrants for wiretapping and other surveillance methods that do not involve a physical trespass.

By contast, U.S. v. Jones, the 2012 decision in which the Supreme Court held that tracking a suspected drug dealer's whereabouts for a month by attaching a GPS device to his car qualified as a search under the Fourth Amendment, emphasized the trespass on the vehicle. That decision left open the question of whether obtaining similar information through methods that do not require such a physical intrusion also implicates the Fourth Amendment. But as the 11th Circuit noted yesterday, at least five justices indicated in Jones that a trespass is not required because the crucial question is whether surveillance violates reasonable expectations of privacy.

If anything, the appeals court said, cellphone records are more revealing than the information at issue in Jones, which was limited to the location of the supect's car on public roads. "One's cell phone, unlike an automobile, can accompany its owner anywhere," the court noted. "Thus, the exposure of the cell site location information can convert what would otherwise be a private event into a public one. When one's whereabouts are not public, then one may have a reasonable expectation of privacy in those whereabouts….While committing a crime is certainly not within a legitimate expectation of privacy, if the cell site location data could place [Davis] near those scenes, it could place him near any other scene. There is a reasonable privacy interest in being near the home of a lover, or a dispensary of medication, or a place of worship, or a house of ill repute."

The 11th Circuit rejected the government's argument that "Davis did not have a reasonable expectation of privacy because he had theretofore surrendered that expectation by exposing his cell site location to his service provider when he placed the call." During Davis' trial a prosecutor conceded that he and an accomplice "probably had no idea that by bringing their cell phones with them to these robberies, they were allowing [their cell service provider] and now all of you to follow their movements on the days and at the times of the robberies." If so, the appeals court said, it is hardly reasonable to claim that Davis volunteered this information. Since people generally are not even aware that they are revealing their locations when they make calls on their cellphones, and since such information is revealed even when people answer calls from others, the court said, the idea that every cellphone user is voluntarily sharing his whereabouts with the world is implausible. Hence "Davis has not voluntarily disclosed his cell site location information to the provider in such a fashion as to lose his reasonable expectation of privacy."

Here the appeals court is trying to get around the Supreme Court's "third party doctrine," which holds that "a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties." Under that doctrine, the government's access to a huge amount of highly revealing information stored on remote computers is completely unrestricted by the Fourth Amendment; it is subject only to statutory limitations such as those imposed by the Stored Communications Act. As Justice Sonia Sotomayor suggested in Jones, a reconsideration of the third-party doctrine is long ovderdue. But since such a reconsideration is beyond the authority of an appeals court, the 11th Circuit instead argues that cellphone location information falls outside the doctrine because it is not shared knowingly and willingly.

The problem with this approach is that people are becoming increasingly aware, due partly to the publicity surrounding cases like this one, that using a cellphone creates a trove of information about their movements. Once that is a matter of common knowledge, will the constitutional analysis change? Does a reasonable expectation of privacy depend on ignorance of the ease with which privacy can be violated?

If so, I guess we are only making things easier for the government by reporting on this issue. Last year in Reason, Ron Bailey explained "how the surveillance state co-opted personal technology." More on cellphone tracking here.