Cellphone tracking: Police must obtain warrants, N.J. court says

State courts and legislatures are grappling with the murky legal principles governing police surveillance and privacy. One point of concern: GPS-enabled smart phones can now reveal razor-sharp details about a person’s movements.

Highlighting once again America’s struggle with government surveillance and personal privacy in the digital age, the New Jersey Supreme Court announced “a new rule of law” on Thursday, forbidding police to obtain a suspect’s cellphone data without a warrant.

The decision comes in the aftermath of Edward Snowden’s leak of government secrets that revealed massive government surveillance programs. Among other things, the programs allow law enforcement officials to collect “metadata” from phone companies – a practice that has just been reauthorized by a secret US court that oversees intelligence activities.

The ruling also comes at a time when state courts and legislatures across the United States are grappling with the murky legal principles governing state laws about police surveillance and privacy. Breathtaking changes in technology mean that a GPS-enabled smart phone can now reveal razor-sharp details about a person’s movements, thus quickly changing traditional notions of privacy. Technological advancements have also made it easier for local police to obtain information from service providers.

So the New Jersey court is one of the first to issue a full-throated ruling that a person’s location information is private and that police must obtain a full warrant based on probable cause before being able to obtain it.

The ruling also makes this a “right” to privacy, grounding it in the state’s constitution rather than in specific legislation.

“Litigants try to stay away from getting courts to make new law, because courts can be kind of reluctant to do so,” says Alex Chopin, a partner with Patton Boggs in Washington, D.C., and an expert in privacy law and social networking. “So I thought it was very bold that New Jersey said, we are making a new rule of law here, and explicitly said, this expectation of privacy is legitimate and law enforcement needs to follow it.”

In May, Montana Gov. Steve Bullock (D) signed the nation’s first bill that requires police to get court permission before tracking individuals with their GPS location information. And earlier this month, the legislature in Maine overrode the governor’s veto of a similar act that barred police from obtaining location information without a warrant.

But other state and federal laws, as well as previous legal precedents, are often ill-equipped to parse the privacy status of such easy-to-glean digital data. And such information is becoming more and more the matrix of everyday life, as GPS devices are affixed to people’s hips.

“Now cellphone tracking information is so detailed that a cellphone provider can track you to your living room, or even the floor of the house you’re in, and that wasn’t possible at the time [the New Jersey] case was ongoing,” Ms. Chopin says.

Before the advent of this kind of technology, it was somewhat simpler for courts to distinguish between public and private spheres. Police have long been allowed to observe suspects in public or obtain publicly available private information without a warrant. But today’s technology is quickly blurring the lines.

“Using a cellphone to determine the location of its owner can be far more revealing than acquiring toll billing, bank, or Internet subscriber records,” wrote Chief Justice Stuart Rabner in Thursday’s opinion. “Details about the location of a cellphone can provide an intimate picture of one’s daily life and reveal not just where people go – which doctors, religious services and stores they visit – but also the people and groups they choose to affiliate with.”

At the same time, police have often aggressively used the digital surveillance that a phone company can instantly provide. An American Civil Liberties Union study last year found that police departments across the nation were regularly taking advantage of GPS tracking information, without court approval and often without probable cause.

“With the advance in technology, the police no longer have to surveil [suspects] themselves; they can rely upon the cellphone companies to do their surveillance for them,” says Rubin Sinins, the attorney who wrote a friend-of-the-court brief on behalf of the ACLU and argued this case before the court.

The ACLU study revealed a patchwork of policies and legal principles guiding local law enforcement’s respect for private information. Some police departments require the data only to be “relevant and material” to investigations – a bar much lower than probable cause. Other departments order the entire batch of cellphone numbers registered by GPS devices at a particular location, a practice known as a “tower dump.”

Service providers, too, have taken advantage of the blurry legal principles surrounding the privacy of customer data, some going so far as to market GPS location data to law enforcement officials, complete with a list of “surveillance fees” they will charge police to obtain it.

Maine’s new law, however, requires cellphone companies to make sure the warrants that police provide are not more than 10 days old. It also requires the companies to inform a user within three days that police have requested his or her information.

New legislation notwithstanding, the New Jersey case could help set a precedent for such location data to be included within constitutional definitions of privacy.

“In the absence of a constitutionally recognized privacy interest,” says Mr. Sinins, “there’s no disincentive for police to track people without a court order.”