Victory! Because where you go can reveal who you are, the ACLU believes that the government's acquisition of cell site location information (CSLI) should require a warrant. In 2014, we won an enormous victory from the Massachusetts Supreme Judicial Court for this type of privacy in the digital age, in Commonwealth v. Augustine.

Echoing the NSA’s view that the constitution does not protect information that our service providers possess about us, the Commonwealth claimed in Augustine that cell phone users do not have a constitutionally protected interest in the CSLI that their phones automatically generate when used to make or receive calls. As a result, the Commonwealth argued that the government can warrantlessly target the movements of cell phone users without probable cause.

The ACLU of Massachusetts and national ACLU litigated the appeal in Augustine, arguing that the Commonwealth's claim undermined the protections of Article 14 of the Massachusetts Declaration of Rights, as well as the Fourth Amendment to the United States Constitution.

In February 2014, the Supreme Judicial Court issued a landmark decision, ruling that people do have a reasonable expectation of privacy in the location data that cell phone companies hold about them, and that a warrant will therefore often be required when local or state police attempt to track cell phones in Massachusetts. This decision set an important national precedent, as Massachusetts became only the second state supreme court in the country to impose a warrant requirement for CSLI. Numerous states have since followed Massachusetts’ lead in both judicial opinions and legislation.

On August 18, 2015, the Supreme Judicial Court overturned an order to suppress CSLI information in this case, but reaffirmed the need to show probable cause to obtain this data.



Matthew Segal, Jessie Rossman, Mason Kortz (ACLU of Massachusetts); Nathan Freed Wessler (ACLU)