Use a Cellphone, Void the Fourth Amendment?

In May, the Indiana Supreme Court tackled one of the most pressing questions in modern Fourth Amendment law: When the police decide to use someone's cellphone to track his location, do they need a search warrant to get the data from his cellular service provider?

In Zanders v. Indiana, cops obtained Marcus Zanders' cell site data without a warrant and used that information to trace back his whereabouts during the time periods in which several armed robberies were committed. Those records were later used against Zanders at trial.

Cellphones are "double-edged swords, increasing convenience at the expense of privacy," the Indiana Supreme Court observed. The justices then demonstrated just how expensive the costs to privacy can be. "Zanders presumptively knew that his phone makes and receives calls by sending signals to towers," the decision said, "and that Sprint keeps records of these signals for business purposes like billing and tracking tower usage." Because customers have no "reasonable expectation of privacy" in such records, the court ruled, the Fourth Amendment offers them no protection when the police obtain those records without a warrant.

The state Supreme Court claimed that its hands were tied and that it had no choice but to rule in favor of the police due to controlling U.S. Supreme Court precedents. In Katz v. United States (1967), for example, the Court held that "what a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection." Even more significantly, in Smith v. Maryland (1979), the Court ruled that "a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties."

This legal standard, also known as the "third-party doctrine," places the Fourth Amendment right to be free from unreasonable search and seizure in direct conflict with the vast warrantless powers that law enforcement agencies now routinely enjoy. Something has to give.

How many Fourth Amendment protections do we forfeit when we use a cellphone? The U.S. Supreme Court will eventually have to face that question. It's high time it gave the third-party doctrine a second look.