Jacob Sullum

Last month the New Jersey Supreme Court ruled that police generally need a warrant to obtain information about the locations of cellphone users. Last week 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 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," an increasingly alarming menace to privacy.

Since the early 1970s, the U.S. Supreme Court has repeatedly declared that people have no constitutional right to privacy with respect to information they voluntarily share with others. New Jersey's courts have always rejected this principle, recognizing that people who disclose information for particular purposes do not thereby surrender all expectations of privacy.

A unanimous New Jersey Supreme Court therefore had no difficulty concluding that the government may not demand cellphone location data at will. "Disclosure of cellphone location information, which cellphone 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 cellphones to serve as tracking devices or reasonably expect them to be used by the government in that way."

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 appeals court said, meaning they receive only as much protection as legislatures give them. While the case involved requests for two months of specific customers' location data, the court's logic would also apply to less discriminating investigations.

Suppose the National Security Agency, in addition to collecting information about the destinations, timing and length of our calls, decided to amass a comprehensive database showing everywhere we go with our cellphones. It may be doing something like that already.

Jacob Sullum

Jacob Sullum is a senior editor at Reason magazine and a contributing columnist on Townhall.com.
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