SJC places safeguards on use of cellphone ‘tower dumps’
Court requires a search warrant to obtain data
THE SUPREME JUDICIAL COURT will allow the police to continue using “tower dumps,” requests for broad swaths of cellphone data, despite pleas from privacy activists to eliminate the practice. But the state’s highest court, in a unanimous 52-page ruling issued Friday, agreed with advocates that a “tower dump” is considered a seizure that intrudes on someone’s right to privacy, and put in place new safeguards regarding how they can be used, including a new requirement that the police obtain a search warrant.
“Henceforth, before acquiring and analyzing a series of tower dumps, the Commonwealth must obtain a warrant from a judge,” wrote Justice Frank Gaziano.
Requiring a judge – not a magistrate – to issue a search warrant is the same standard used to apply for a warrant for a wiretap or a body cavity search, which are considered the most invasive types of searches. Under the SJC ruling, the warrant must also include “protocols for the prompt and permanent disposal of any and all data that does not fit within the object of the search following the conclusion of the prosecution.”
The data disposal requirement is meant to address what Gaziano described as “the potential invasions of privacy that could befall those innocent and uninvolved third parties” whose data could be uncovered by the search.
“Unlike defendants in criminal cases, these individuals may never know that their [cell site location information] was provided to law enforcement, let alone be able to exercise any sort of control or oversight over how their data is used,” Gaziano wrote. “Such a situation presents far too great a risk of unwarranted invasions of privacy, whether intentional or inadvertent, malicious or innocent.”
The ruling will not apply retroactively, but only to new or currently active cases.
Jessie Rossman, managing attorney at the ACLU of Massachusetts, which had argued that more safeguards are needed on the police use of tower dumps, called the ruling “a groundbreaking decision that provides crucial privacy protections for people in Massachusetts.” “The message is clear: If the police use tower dumps over multiple days to identify someone they believe to have committed crimes, they must first get a warrant, and they must promptly discard any data they acquire from those tower dumps about people other than the target,” Rossman said.
Nathan Freed Wessler, deputy director of the ACLU’s Speech, Privacy, and Technology Project, said in a statement that the SJC’s decision “solidifies the Massachusetts Supreme Judicial Court’s role as a leading voice on privacy in the digital age.”
Suffolk District Attorney Kevin Hayden, whose office prosecuted the case, said criminal investigations, like all aspects of modern life, are affected by constant advancements in technology. “While this decision does not impact our ability to move forward on the underlying case, it brings clarity to how law enforcement agencies can go about collecting technological evidence they deem important to an investigation,” Hayden said. “We welcome that clarity.”
The case stemmed from an investigation into six armed robberies in stores in Boston, Canton, and Cambridge. On a seventh occasion, a perpetrator fatally shot a Boston store clerk during an attempted robbery. The police believed the same perpetrator, along with a getaway driver, conducted all the robberies, so they obtained search warrants for cellphone data from towers near the robberies to identify anyone who had been in the vicinity of all the robberies at the times they occurred. There was one warrant obtained for the four earliest robberies, and a separate warrant for the two later robberies and the homicide.
The police obtained information about 50,951 unique phone numbers and identified Jerron Perry and Gregory Simmons as suspects. After additional investigation, the men were arrested. Perry contested the use of the tower dump data as evidence, arguing that the warrant was too broad and infringed on his privacy rights.
Gaziano wrote that using the cellphone data to track Perry’s location on several days, determine his identity, and discover who he was calling implicates his constitutional right to privacy, since it “provided investigators with information of a highly personal and private nature” that they could not have gotten through other techniques.In the case of the two later robberies and the shooting, the court found that the police had reason to believe that the perpetrator communicated with a getaway car driver, so there was probable cause to believe that cellphone data could be used to identify a suspect. However, in the earlier robberies, the police had no evidence a cellphone was used to commit the crimes, and a general assumption that people carry cellphones is not enough to establish probable cause.
The court rejected arguments by privacy advocates that tower dumps should only be used to identify a particular suspect’s movements. The court said tower dumps can be used in a case like this to identify an unknown suspect.