Surveillance is the backbone of many criminal investigations, but keeping track of a person's movements can be time consuming and expensive with multiple teams of investigators rotating around-the-clock to keep tabs.
Law enforcement agencies investigating a series of retail store robberies in Detroit employed a different method to track the movements of one of the suspects though: they used cell phone records. Defense attorneys challenged their client's conviction and 116-year sentence by claiming the release of the cell phone records to the government violated their client's rights, because they were obtained without a search warrant. The U.S. Supreme Court agreed with the defense lawyers recently in the case of Carpenter vs. United States.
Most people give little thought to the technology set in motion when they make a call using their smartphone. The technology that makes it possible for you to call a local restaurant to order lunch or simply talk to a friend leaves behind a trail that investigators can use to track where your phone has been.
The companies providing cell phone service keep records of each mobile device using their network. Making a call from your cell phone requires that it connect with a local tower linked to the service provider's network. As you move from one location to another with your phone, you are able to maintain a connection with the network while the connection jumps from one tower or cell site to another. If there is no cell site within range of your phone, your will be unable to make a call, or your current call will be dropped.
As your signal moves from one cell site to the next, the service provider maintains records of the phone's movement. These records of calls and texts are known as historic cell site location information (CSLI). Anyone, including law enforcement agencies, could track the movements of a particular phone in much the same way that GPS trackers pinpoint a device's location. CSLI do not, however, give as precise a location as GPS. For example, GPS can pinpoint a device within 5 to 10 feet of its actual location, but the accuracy of using a triangulation technique based upon CSLI records covers a much wider area with ranging anywhere from a few blocks to several miles of the phone's actual location.
The investigation into a series of armed robberies included a confession by one of the suspects. The confession relayed the cell phone numbers of other suspects related to the crimes. The FBI used this information to obtain CSLI records from the carriers under the Stored Communications Act authorizing the release of stored records when needed in a criminal investigation.
Writing for a 5-4 majority of the Court, Chief Justice John Roberts found the court order used by the FBI to obtain the CSLI records under the federal statute was not a search warrant based upon probable cause as required by the Fourth Amendment to the U.S. Constitution. The method of obtaining the records violated the individual's reasonable expectation of privacy, so the Court reversed lower court rulings upholding the method's constitutionality and remanded the case.
The majority of the Court refused to accept the government's argument the records were admissible under the third-party doctrine. The doctrine excludes information disclosed to third parties (in this case the cellphone companies) from protections afforded by the Fourth Amendment. Chief Justice Roberts put great emphasis on the extensiveness of the CSLI records and the intrusiveness into a person's private life resulting from them.
The Court's decision in Carpenter is consistent with its unanimous 2012 ruling in United States v. Jones challenging the constitutionality of police tracking a suspect through a GPS device secretly attached to the suspect's car. The decision by Justice Scalia declared the use of the GPS device to be a search under the Fourth Amendment that violated the individual's reasonable expectation of privacy. Concurring opinions in the Jones case raised questions about whether other forms of electronic surveillance of people's movements while in public, including the use of video cameras in public places, might also raise Fourth Amendment privacy concerns.
A lesson to be learned from cases such as Carpenter and Jones is that criminal defense counsel must be diligent in challenging how government uses technology to investigate criminal cases. In particular, the Carpenter decision did not specifically preclude government access in criminal investigations to other types of personal records, such as emails and bank records, held by third-party sources. This remains an area worthy of close observation by defense attorneys.
