Today, the 3rd Circuit Court of Appeals decided (PDF) — in the first appellate opinion to address the issue — that the Stored Communications Act (SCA) protects historical cell phone location information from disclosure to the government, and that under the SCA, magistrate judges may order the government to obtain a warrant before accessing such information. In this decision, the court recognized that information about people's past whereabouts can implicate privacy interests protected by the Fourth Amendment because, for example, it may reveal details of what is happening inside of the privacy of the home.

This case began when the government submitted an application to a federal district court in the Western District of Pennsylvania requesting historical cell site location information for a particular person's phone number (i.e., information about what cell phone tower and what sector of the tower was receiving signals from the phone at a given time). The government argued that it can access this information merely by showing that the information is "relevant and material to an ongoing criminal investigation" — a standard much lower than the warrant standard usually required by the Fourth Amendment for searches.

In February 2008, in an extensive opinion (PDF) joined by all magistrate judges in the district, Magistrate Judge Lisa Pupo Lenihan denied the application, holding that the SCA does not authorize the government to obtain cell phone location information under the "relevant and material" standard, and that warrantless access to this information may violate the cell phone user's Fourth Amendment rights. The district court agreed with the magistrates' decision (PDF), and the government appealed this decision. The ACLU, the ACLU of Pennsylvania, the Electronic Frontier Foundation, and the Center for Democracy and Technology submitted friend-of-the-court briefs at the district and appellate court levels to oppose the government's request.

Today, the 3rd Circuit disagreed with the lower court order and remanded it back to the magistrate judge for further proceedings. But in its decision, the 3rd Circuit adopted our view that the SCA gives judges the discretion to require a warrant when the government seeks historical cell phone location information. The court also agreed with us that cell phone users have not given up their Fourth Amendment right to privacy just because their location information is shared with a third party, i.e., their cell phone provider. The court recognized that "[a] cell phone customer has not 'voluntarily' shared his location information with a cellular provider in any meaningful way."

The 3rd Circuit also instructed the magistrate judge to "make fact findings and give a full explanation that balances the government's need (not merely desire) for the information with the privacy interests of cell phone users."

So, the fight for the privacy interest of the cell phone user in this case will continue. Today's decision is an important victory in protecting the privacy interest of cell phone users in their location information.