Massachusetts State House.
Boston Bar Journal

Oh, the Places You’ve Been! Preserving Privacy in a Cellular Age

September 12, 2012
| Fall 2012, Vol 56, #4

By Sara E. Silva

Vantage Point

Everyone knows that our daily actions are sometimes recorded.  Our Fast Lane accounts create a record of every toll we pay.  When we bank or shop, surveillance cameras or credit card payment records may reflect where we were.  But when we exit the Pike, or leave the bank or the store, we do not expect the government to continuously track our movements to more private and personal places: doctors’ offices, houses of worship, daycares, homes.

Cell phone location data allows the government to do exactly that, and has become an incredibly powerful tool for law enforcement.  In the past year, cell phone carriers responded to 1.3 million demands from law enforcement for subscriber information and location data, often without a warrant, probable cause, or any judicial oversight whatsoever.  See Eric Lichtblau, More Demands on Cell Carriers on Surveillance, New York Times (July 8, 2012), available at  After United States v. Jones, 132 S. Ct. 945 (2012), however, criminal defense lawyers have greater room to argue that the Fourth Amendment protects location information.  Jones held that the warrantless installation of a GPS unit to track the movements of a vehicle violates the Fourth Amendment.  Although the majority opinion was based on the physical trespass involved, five Justices agreed that probable cause and a warrant are required when law enforcement uses vehicle tracking technology to aggregate a person’s movements over time.  Id. at 955-56 (Sotomayor, J., concurring); 964 (Alito, J., concurring in the judgment).

A cell phone can be the equivalent of a tracking device installed on our bodies.  Eight in ten American adults own a cell phone.  See Pew Research Center, Americans and Their Cell Phones (Aug. 15, 2011), available at  Most cell phones come equipped with GPS chips, which allow cell phone providers to obtain real-time GPS data from the phones carried by their subscribers.  Even phones without GPS can provide highly accurate location information, however.  When turned on, cell phones automatically and regularly communicate with the towers that serve their provider networks to ensure that they are connected with the tower with the best reception.  Through these communications, the phones transmit certain pieces of data such as the strength, angle and timing of the signal.  This data, when analyzed, discloses the location of the phone at the time of the communication; when triangulated between two or more towers, the location data can be highly accurate.  How frequently a phone reveals its location varies by provider, but it occurs automatically multiple times a minute, providing a comprehensive record of one’s movements.  What may be most disturbing is that to transmit this information, the phone need not be in use.   It just needs to be on.  There is no way for the phone’s owner to know when these communications occur, and no way, short of shutting the phone off, to stop them from happening.

Providers use this data for business purposes – to determine where to build new towers, or how and where their subscribers use their devices.  This means both that location data remains accessible for a long time and that its accuracy is constantly improving to enhance its usefulness.  Increased numbers of cell towers also enhance the precision of location data.  Whereas earlier triangulated data may have been able to narrow a phone’s location to a particular block, some commentators believe that it can now surpass GPS for accuracy in certain areas.  See, e.g., Statement of Prof. Matt Blaze before House Subcommittee on Crime, Terrorism and Homeland Security at 15 (May 17, 2012), available at

Courts in Massachusetts have long permitted law enforcement to obtain historical cell phone location data simply upon a showing that the information is “relevant and material to an ongoing criminal investigation,” assuming that “there is nothing [about tracking data] that is any more incriminating or revealing than what could be gleaned from the activation of a pen register or from physical surveillance,” and that “outside of the home it is doubtful that the tracking of a cell phone has any Fourth Amendment implication whatsoever.”  See In re Applications of the United States of America for Orders Pursuant to Title 18, United States Code, Section 2703(d), 509 F. Supp. 2d 76, 77-79, 81 (D. Mass. 2007) (Stearns, J.).

These assumptions are ripe for challenge after Jones.  Warrantless access to GPS cell phone information is likely unconstitutional.  Jones, 132 S. Ct. at 955-56 (Sotomayor, J., concurring); see also id. at 964 (Alito, J., concurring in the judgment).  Like GPS information, triangulated cell phone location data “generates a precise, comprehensive record of a person’s public movements that reflects a wealth of detail about her familial, political, professional, religious, and sexual associations.”  Jones, 132 S. Ct. at 955-56 (Sotomayor, J., concurring) (citations omitted).  Such intimate detail is practically impossible to aggregate through visual surveillance.  See id. at 956.  And the ease with which law enforcement can access it renders it highly “amenable to abuse.”  Id.

Since Jones, at least one Superior Court Justice has required a warrant for cell phone location information.  Commonwealth v. Pitt, 29 Mass. L. Rptr. 445, *3 n.5, *8, *10 (Mass. Super. Ct. Feb. 23, 2012) (Cosgrove, J.) (location data reveals “trips to the psychiatrist, the plastic surgeon, the abortion clinic, the AIDS treatment center, the strip club, the criminal defense attorney, the by-the-hour motel, the union meeting, the mosque, the synagogue or church, the gay bar, and on and on . . . . [T]he extent of this potential incursion . . . unquestionably implicates Fourth Amendment privacy rights”) (quoting Jones, 132 S. Ct. at 955) (Sotomayor, J. concurring).  The federal court is also poised to revisit the issue.  See In the Matter of the Application of the United States of America for an Order Pursuant to Title 18, United States Code, Section 2703(d) to Disclose Subscriber Information and Cell Site Information, __ F. Supp. 2d. __, 2012 WL 989638, *1-2 (D. Mass. March 23, 2012) (Collings, M.J.).

Cell phone location data can tell the government precisely where we have been every minute of the day.  Defense counsel should use Jones to press the argument that law enforcement cannot constitutionally mine this potent source of information without probable cause and a warrant.

Sara Silva, a partner with Collora LLP, represents individuals and corporations in the areas of white collar criminal defense and complex civil litigation.