Last week, the New Jersey Supreme Court held in State v. Earls that New Jersey residents have a constitutional right of privacy in their cell phone location data, and that law enforcement officers must obtain a search warrant in order to access the data. In the case, the police were searching for a suspected burglar and his girlfriend. In that effort, they contacted a cell phone service provider. At three different times that evening, the service provider gave information about the location of the suspected burglar’s cell phone. After the Appellate Division concluded that defendant lacked a reasonable expectation of privacy in his cell phone location information, the Supreme Court held that the New Jersey Constitution protects an individual’s privacy interest in his or her cell phone, and that the police must obtain a warrant based on probable cause (or must qualify for a warrant requirement exception) to obtain location information from a cell phone. The court noted:

“When people make disclosures to phone companies and other providers to use their services, they are not promoting the release of personal information to others. Instead, they can reasonably expect that their personal information will remain private… Today, cell phones can be pinpointed with great precision, but courts are not adept at calculating a person’s legitimate expectation of privacy with mathematical certainty. What is clear is that cell phones are not meant to serve as tracking devices to locate their owners wherever they may be. No one buys a cell phone to share detailed information about their whereabouts with the police.”

If the opinion had found the right to locational privacy from the government under the federal Constitution, Earls could be undermined by subsequent federal court decisions. But the New Jersey Supreme Court has the final say over what New Jersey’s Constitution means. No court in the country can overturn the New Jersey Supreme Court’s decision that there is a state constitutional right against warrantless collection of cell phone location data by law enforcement. By framing the issue in state constitutional terms, Chief Justice Rabner insulated the decision from further review, and settled an issue in New Jersey that is unsettled across the country in the wake of the United States Supreme Court’s decision in the GPS privacy case, US v. Jones.

Earls does not apply directly to anyone but New Jersey state actors. Because the state government can exert so much power over individual citizens, the state is often constrained in ways that private companies are not.

However, the court’s reasoning – that cell phone location data can reveal “which shops, doctors, religious services, and political events [people] go to, and with whom they choose to associate” – is very much in line with the reasoning of those pushing for more legislation or regulation on geolocation data. And with more and more companies collecting location data in the mobile app space, this ruling has the potential to indirectly apply to any company that records location data about New Jersey residents and may be asked for it by law enforcement. Companies need to ensure they are not just handing this data away any time a police officer requests it, even if pursuant to a criminal investigation. Companies should also make sure that they understand the warrant requirement and that it is communicated clearly to all of their employees with access to the data. Otherwise, they run the risk of legal backlash from consumers.

As courts across the country continue to consider how to apply constitutional rights to new forms of technology, we’ll continue to monitor these cases closely.