Police in two northeast states will now have to obtain a warrant before tracking a suspect’s cellphone location to monitor their movements.

Massachusetts’ Supreme Court ruled this week that individuals enjoy the right to privacy when it comes to their cell phones and for the government to not follow their whereabouts through such technology—unless a court approves this kind of surveillance.

The 5-2 decision came in Commonwealth v. Augustine (pdf), in which state police obtained two weeks of the plaintiffs’ cell records from Sprint without getting a warrant from a judge.

Instead, authorities used federal law to get permission for the phone records.

A lower court judge ruled police had violated the Massachusetts constitution in taking this action, and when the state appealed, the Supreme Court sided with the judge.

“Even though restricted to telephone calls sent and received (answered or unanswered), the tracking of the defendant’s movements in the urban Boston area for two weeks was more than sufficient to intrude upon the defendant’s expectation of privacy,” the majority opinion said.

The ruling was very similar to one by New Jersey’s highest court, which decided in 2013 that Americans have a constitutional right to privacy in cell-phone location information.

Christopher Ott, a spokesman for the American Civil Liberties Union of Massachusetts, told The Wall Street Journal that the two rulings will hopefully “lead the way for other courts that are bound to be dealing with this issue.”

-Noel Brinkerhoff

To Learn More:

New Massachusetts Decision Requires Warrant for Cell Tracking (by Hanni Fakhoury, Electronic Frontier Foundation)

High Court in Massachusetts Rules Cell-Phone Data Requires Warrant (by Jacob Gershman, Wall Street Journal)

New Jersey Supreme Court First to Order Warrants for Cell Phone Tracking (by Matt Bewig, AllGov)