WASHINGTON — In a victory for privacy in the digital era, the Supreme Court ruled Friday that the Constitution protects tracking data from a cellphone, requiring police to have a search warrant to obtain cell tower records that show a person’s movement for days or weeks.
The justices, in a 5-4 decision, said the Fourth Amendment protects the data from being searched without a warrant, even though these records are collected and held by a private company, not the government.
In Carpenter v. United States, the court ruled for the alleged leader of an armed robbery gang in the Detroit area whose movements were tracked for 127 days using data from his cellphones. The ruling reflects the high court’s increasing concern over the vast amount of private information that can be obtained and stored through digital technology , often without the knowledge of the user.
It is one area where the progressive left and the libertarian right are in agreement, and that too is reflected among the justices.
Six years ago, the high court voted 9-0 to set aside the conviction of a Washington-area drug dealer whose daily movements had been tracked by a GPS device that police had secretly attached to his vehicle. Four years ago, the justices ruled unanimously in a San Diego case that police need a search warrant before they may download the contents of a suspect’s smartphone.
But despite those unanimous votes, the justices had been uncertain about extending privacy rights to business records and other information that customers routinely turn over to others.
In the past, the court has drawn a sharp distinction between what is private under the law and what is not. For example, talking on a phone is considered private, so police must obtain a search warrant before they may wiretap or otherwise listen to a call. However, the dialing records of phone calls were considered a business record and not private, so police may obtain these records directly from a phone company.
The case decided Friday arose from a series of nine armed robberies of Radio Shacks and T-Mobile stores in Michigan and Ohio in 2010 and 2011.
Timothy Carpenter was alleged to be the ring leader. The FBI sought data from cellphone towers that would allow investigators to track his movements for 127 days. When Carpenter used his cellphone, it connected to a nearby tower, giving police the information that helped convict him.
Under a federal law known as the Stored Communications Act, investigators may obtain these records if they go before a judge and show they have facts demonstrating the phone data are “relevant and material to an ongoing criminal investigation.” However, they were not required to obtain a search warrant based on “probable cause” — a slightly higher standard.
At his trial, Carpenter sought to have the cell tower data excluded on the grounds it arose from an “unreasonable search” in violation of the Fourth Amendment. A federal judge denied the motion. The court of appeals agreed on the grounds that business records — from checks held by a bank or dialing records held by a phone company — are not private and may be obtained by police investigators.
Chief Justice John Roberts, joined by the court’s four liberals, wrote that “an individual maintains a legitimate expectation of privacy in the record of his physical movements” as they are captured by cellphone towers. Roberts said the court’s decision does not affect other business records, including those held by banks.
He also wrote that police still can respond to an emergency and obtain records without a warrant.
Justices Anthony Kennedy, Samuel Alito, Clarence Thomas and Neil Gorsuch each wrote dissenting opinions. Kennedy wrote that the court’s “new and uncharted course will inhibit law enforcement” and “keep defendants and judges guessing for years to come.”
This report includes material from the Associated Press.