The issue of cell phone privacy took center stage this week at the U.S. Supreme Court, which agreed Monday to take up a case concerning cell phone privacy. The case involves the right of law enforcement and other government agencies to access mobile phone subscriber cell site location information (CSLI) without a warrant and whether such access violates Fourth Amendment rights against unreasonable search and seizure. One constitutional law expert has described the case as one which holds “enormous implications” over the ability of government officials to obtain access to subscriber phone use and other data held by wireless carriers. The case at hand, Carpenter v. United States, was brought to the high court by an individual who was convicted in a series of armed robberies which took place in the states of Ohio and Michigan. Prosecutors secured the conviction with the help of CSLI that was provided by MetroPCS and Sprint pursuant to the Stored Communications Act (SCA) and that placed the suspect within a half mile of the crime scenes at the times the robberies occurred.

Under the SCA, which dates back to 1986, law enforcement officials need not obtain a warrant or show probable cause to access customer phone records, and are required only to demonstrate that “reasonable grounds” for such access exist. In similar cases that have come before the courts, law enforcement officials have also cited the “third party doctrine,” which was enunciated in 1979 by the U.S. Supreme Court in Smith v. Maryland. Concluding that a robbery suspect in that case had voluntarily handed over his information to a third party—i.e., the suspect’s wireline phone service provider—the high court ruled that the suspect’s privacy rights did not extend to numbers dialed from his telephone.

By a vote of 2-1, the Sixth Circuit Court of Appeals rejected the petitioner’s claim that application of the SCA to wireless telecommunications data violates the Fourth Amendment. Last October, five civil liberties groups led by the Electronic Frontier Foundation (EFF) petitioned the Supreme Court for writs of certiorari concerning the Sixth Circuit ruling and a separate but related pronouncement issued by the Fourth Circuit Court in U.S. v. Graham. That case acknowledged that the Supreme Court “may in the future limit, or even eliminate, the third-party doctrine . . . but, without, a change in controlling law, we cannot conclude that the government violated the Fourth Amendment.” Pointing to “the dramatic increase in the number of cell phones and cell sites and the amount of detailed, sensitive location data they generate,” the petitioners advised the justices, “it is time for this court to address the Fourth Amendment privacy implications of CSLI.”

As he welcomed the Supreme Court’s announcement, an official of the American Civil Liberty Union Speech, Privacy and Technology Project argued that, “because cell phone location records can reveal countless details of our lives, police should only be able to access them by getting a warrant based on probable cause.” The Supreme Court is expected to conduct oral arguments and issue its decision during the court’s upcoming term, which begins in October.