There's heartening news for our location privacy out of Massachusetts this week. The Supreme Judicial Court, the state's highest court, ruled that police access to real-time cell phone location data—whether it comes from a phone company or from technology like a cell site simulator—intrudes on a person’s reasonable expectation of privacy. Absent exigent circumstances, the court held, the police must get a warrant.

In Commonwealth of Massachusetts v. Almonor, police had a phone carrier “ping” the cell phone of a suspect in a murder case—surreptitiously accessing GPS functions and causing the phone to send its coordinates back to the phone carrier and the police. This real-time location data pinpointed Mr. Almonor’s phone to a location inside a private home. The state argued it could warrantlessly get cell phone location data to find anyone, anytime, at any place as long as it was less than six hours old. A trial court disagreed and the state appealed.

EFF filed an amicus brief in this case in partnership with the ACLU and the Massachusetts Association of Criminal Defense Lawyers. We asked the court to recognize, as the Supreme Court did in U.S. v Carpenter, that people have a constitutional right to privacy in their physical movements. We argued that, because people have their phones with them all the time, and because the location information produced by the phone can reveal our every move—where and with whom we live, socialize, visit, vacation, worship, and much more—the police must get a warrant to access this sensitive information.

The Massachusetts court held that “[m]anipulating our phones for the purpose of identifying and tracking our personal location presents an even greater intrusion” than accessing the historical location data at issue in Carpenter. It concluded that “by causing the defendant's cell phone to reveal its real-time location, the Commonwealth intruded on the defendant's reasonable expectation of privacy in the real-time location of his cell phone.” The court recognized both that cell phone use is ubiquitous in our society, and that a phone’s location is a “proxy” for its owner’s location. The court noted that “society's expectation has been that law enforcement could not secretly and instantly identify a person's real-time physical location at will,” and “[a]llowing law enforcement to immediately locate an individual whose whereabouts were previously unknown by compelling that individual's cell phone to reveal its location contravenes that expectation.”

Much of the majority’s opinion focuses on the fact that, in this case, law enforcement directed the phone company to “manipulate” the defendant’s phone, causing it to send its location to the phone company. In other words, the phone company wouldn’t have collected the data on its own as part of its normal business practices. But two judges, in a concurring opinion, expressed concern that this focus on law enforcement action—rather than on the collection of location data alone—would result in an exception for searches of real-time location data that providers collect automatically. The concurring justices would hold that the Massachusetts constitution “protects us from pings not because of the right to keep the government from interfering with our cellular telephones, but because of the right to keep the government from finding us.”

This is very concerning because, as the concurring justices note, the majority’s focus on government action here could allow the police to “side-step the constitutional protection” by just asking for the data the cell service provider collects on its own. Although the majority denied that would happen, it remains to be seen, both how officers will implement searches after this opinion and how lower courts will apply constitutional law to those searches. We’ve seen the Commonwealth interpret this court’s prior decisions on location tracking very narrowly in the past.

Although the defendant raised both federal and state constitutional claims in Almonor, the court based its decision solely on Article 14 of the Massachusetts Declaration of Rights, which was drafted before—and served as one of the models for—our federal Bill of Rights. Article 14, one of the cornerstones of the Massachusetts Constitution, is the state’s equivalent to the Fourth Amendment. As the court notes, it “does, or may, afford more substantive protection to individuals than that which prevails under the Constitution of the United States.”

Courts around the country are now being asked to address the scope of the Carpenter ruling. Almonor in Massachusetts and a case called State of Maine v. O’Donnell, in Maine are among the first to deal directly with how Carpenter should be applied when police track and locate people in real-time. We’re heartened that the Massachusetts court took these issues seriously and made clear that the police must get a warrant, whether they access historical cell phone location data or whether they cause a phone to send its real-time location. We’re still waiting for the Maine court’s opinion in O’Donnell, and we’re actively tracking other cases addressing these issues across the country.