In a case that echoes the controversy over the National Security Agency’s surveillance programs, Massachusetts’ highest court heard arguments Thursday in deliberations that will determine whether police can get a criminal suspect’s cellphone records without a search warrant.

Civil libertarians said the Supreme Judicial Court’s decision will have far-reaching implications for privacy rights in Massachusetts and warned that police would be able to easily access information about anyone’s daily movements unless they are kept in check by a search-warrant requirement.

The case involves the 2004 homicide of a Malden woman, Julaine Jules, and the arrest of her then-boyfriend, Shabazz Augustine, in 2011. During their investigation, prosecutors sought and received Augustine’s cellphone records in order to pinpoint his whereabouts around the time of the killing.


The records were obtained under a federal law that allows a lower threshold of proof than does a search warrant, for which a judge must determine there is probable cause to believe the suspect was involved in a crime.

Privacy rights activists said the turning over of the records violated protections in the Massachusetts Constitution against unreasonable search and seizure.

Without a search warrant, “there is essentially no protection of the privacy of the individual subject to these requests,” Matthew Segal, legal director of the American Civil Liberties Union of Massachusetts argued before the high court Thursday.

The Suffolk County District Attorney’s Office, which is prosecuting the murder case, told the court Augustine failed to show “he had any expectation of privacy” for his cellphone data.

Moreover, the district attorney’s office argued, the records were not even his: They were created and owned by a third party, his cellphone service provider.

Prosecutors also said they had authority under the federal Stored Communications Act, which requires them to show a judge they have “specific” facts to show the records are relevant to their case, without needing a search warrant.


“The records were obtained lawfully under the prevailing statute with the appropriate burden of proof, as we’ve done in countless other cases,” said Jake Wark, a spokesman for Suffolk County District Attorney Dan Conley.

Even though it asserts Augustine’s records were obtained lawfully, the Suffolk County district attorney’s office now routinely seeks search warrants for cellphone data.“The rules have changed since 2004,” Wark said.

Government access to citizens’ cellphone records has become intensely controversial since a former National Security Agency contractor, Edward Snowden, leaked documents last spring showing the NSA routinely collects the phone records of millions of Americans.

But even before the Snowden revelations, courts and legislators across the country were tangling with the issue.

And in July, the New Jersey Supreme Court held unanimously that police there must get a warrant before accessing such information. That same month, however, the US Court of Appeals for the Fifth Circuit, in New Orleans ruled the opposite: Such data can be accessed without a warrant.

Maine and Montana have both passed laws requiring a warrant to get cellphone records. The Massachusetts Legislature is considering a similar bill, sponsored by Democratic Senator Karen E. Spilka of Ashland. But a measure passed by the California Legislature was vetoed by Governor Jerry Brown.

In the Massachusetts case heard Thursday, a Suffolk County Superior Court judge had ruled in February that because cellphone records can reveal a person’s movements and activities in great detail, the records were inadmissible without a search warrant. Prosecutors appealed, bringing the issue before the Supreme Judicial Court.


Every cellphone is a kind of homing device because the cellular network must constantly track the phone’s approximate location. Millions of phones have GPS chips that can determine the phone’s location to within a few feet. Even without GPS, the network can provide information about the phone’s location by tracking which towers its signal are traveling over.

Indeed, the information collected by cellphones can be so useful — and so easily accessed — that carriers are bombarded with requests for records from law enforcement agencies. According to a congressional report last year, the nation’s carriers gave authorities some 1.3 million records of customer cellphone use in 2011.

In the Augustine case, investigators contacted Sprint Nextel Corp. and requested two weeks’ worth of data about the suspect’s phone usage, including location data.

The Massachusetts high court recently waded into a related privacy case, in which police used a GPS tracking device to tail an arson suspect. Ruling on the case of a passenger in the suspect’s vehicle, the court said “a person may reasonably expect not to be subjected to extended GPS electronic surveillance by the government, targeted at his movements, without judicial oversight and a showing of probable cause.”

The American Civil Liberties Union argued that obtaining cellphone records was even “more intrusive” than getting GPS data because today’s smartphones are so sophisticated they can track a user’s movements in minute detail.


But the Suffolk County prosecutor questioned whether cellphone data are as accurate as GPS records, noting the lower court judge did not even consider the issue before ruling that Augustine’s records were inadmissable.

Justices Ralph Gants and Robert Cordy of the Supreme Judicial Court seemed skeptical of the prosecutor's argument. They noted that even if cellphone records weren’t as accurate as GPS files, they could provide investigators with valuable location data.

A ruling is expected in about six months.

Hiawatha Bray can be reached at bray@globe.com.