In July the New Jersey Supreme Court ruled that police generally need a warrant to obtain information about the locations of cellphone users. Less than two weeks later, the U.S. Court of Appeals for the 5th Circuit said just the opposite.
The first decision was based on Article I, Paragraph 7 of the New Jersey Constitution, while the second decision was based on the Fourth Amendment to the U.S. Constitution. But those provisions are virtually identical, banning "unreasonable searches and seizures" of "persons, houses, papers, and effects." The crucial difference between the two decisions is the "third party doctrine," which holds that people have no constitutional right to privacy with respect to information they voluntarily share with others.
Based on a series of Supreme Court decisions beginning in the early 1970s, federal courts are bound by this principle, which New Jersey courts have emphatically rejected. Hence the New Jersey Supreme Court had no difficulty concluding that the government may not demand cellphone location data at will. "Disclosure of cell-phone location information, which cell-phone users must provide to receive service, can reveal a great deal of personal information about an individual," the court noted. "Yet people do not buy cell phones to serve as tracking devices or reasonably expect them to be used by the government in that way. We therefore find that individuals have a reasonable expectation of privacy in the location of their cell phones under the State Constitution."
The 5th Circuit, by contrast, said people should know by now that connecting their wireless phone calls entails transmitting their locations to their service providers. Since no one is forced to use a cellphone, it reasoned, anyone who chooses to do so is voluntarily disclosing his whereabouts to a third party, thereby losing any reasonable expectation of privacy in that information. "Cell site data are business records and should be analyzed under that line of Supreme Court precedent," the court said, meaning they receive only as much protection as legislatures decide to give them.
The 5th Circuit's ruling, the first by a federal appeals court to squarely address this issue, involved requests for two months of specific customers' location data. It sits uneasily with U.S. v. Jones, the 2012 decision in which the Supreme Court said police need a warrant to track a car by attaching a GPS device to it. Although the majority opinion in Jones hinged on the physical intrusion required to install the device, five justices expressed the view that the breadth of information generated by tracking someone's car for a month was enough to trigger Fourth Amendment protection.