BOSTON (AP) — Law enforcement in Massachusetts must get a search warrant before obtaining cellphone records to track someone’s movements in most cases, the state’s highest court ruled Tuesday.
The Supreme Judicial Court ruled 5-2 against prosecutors who wanted a murder suspect’s cellphone records over a two-week period admissible as evidence.
The court ruled that obtaining cell site location information over such a long period without a warrant based on probable cause was an invasion of privacy and a violation of the state Declaration of Rights. Cell site location information shows which cell towers a user’s phone communicates with at the beginning and end of a call, giving that person’s approximate location.
‘‘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 said in the ruling.
Suffolk County prosecutors argued that the information was received from a third party, a cellphone company, and was not specific enough to amount to an invasion of privacy.
The ruling came in the case of Shabazz Augustine, a suspect in the August 2004 slaying of his ex-girlfriend.
Authorities obtained cellphone company records to try to determine Augustine’s whereabouts in the days before and after Julaine Jules was killed. The evidence was suppressed after a Superior Court judge ruled that obtaining the records amounted to a ‘‘warrantless search.’’
Suffolk County prosecutors appealed.
Augustine was indicted in July 2011 and remains in custody awaiting trial.
‘‘This decision is an enormous victory for everyone who cares about privacy,’’ said Matthew Segal, legal director for the American Civil Liberties Union of Massachusetts, which argued the case before the court.
‘‘It says that people can have a constitutionally protected privacy interest in information about them even if that information is in the hands of a third-party service provider like their cellphone company,’’ he said.
The decision leaves open a short window of time in which the records can be obtained without a warrant but does not specify exactly how long, he said.
He also noted that the Massachusetts decision is at odds with the federal government’s justification for National Security Agency metadata collection— that the information is coming from third parties, specifically cellphone companies.
The Suffolk district attorney’s office said it was pleased the case had made it so far through the court system.
‘‘This is a key victory for prosecutors, who appealed the judge’s order to the high court,’’ the office said in a statement. ‘‘Notably, while the majority decision lays out a framework that now requires a search warrant to obtain such evidence instead of a court order, Suffolk prosecutors have been taking that tack for years and no other cases are expected to be implicated.’’
The dissenting opinion drew a distinction between the two types of cell site location information. The second type is called registration cell site location information, which is closer to GPS tracking.
‘‘I believe that those differences have fundamental constitutional consequences with respect to both the reasonableness of the expectation of privacy under the third-party doctrine and the extent of the intrusion on privacy,’’ Justice Ralph Gants wrote in the dissent.