A US Court of Appeals has ruled that police do not need a warrant to track the whereabouts of a person's mobile phone.
The Fourth Circuit Court of Appeals ruled [PDF] that police in Baltimore did not violate the Fourth Amendment rights of two suspected robbers when they pulled the phone location data of the men from their mobile carrier.
In the case US v Graham, authorities placed two men at the scene of armed robberies by using cell-site location information (CSLI) collected from their carrier. The CSLI data is collected when a handset connects to a nearby phone tower and can be used to track a specific device.
Attorneys for the defendants, including the Electronic Frontier Foundation and the American Civil Liberties Union, had argued that because police did not obtain a warrant before demanding that Sprint hand over the CSLI data, they had violated the men's Fourth Amendment rights.
After a district court ruled in favor of the government, the case was kicked over to the appeals court, where a three-judge panel overturned the district court.
The government then appealed the case en banc in front of the entire roster of judges on the Fourth Circuit Court of Appeals. Their decision, issued today, sides with the district court and overturns the panel decision.
Citing the precedent set by previous court decisions on a "third-party doctrine," the court said that the information collected by Sprint was not subject to Fourth Amendment search and seizure protections.
"For the Court has long held that an individual enjoys no Fourth Amendment protection 'in information he voluntarily turns over to [a] third part[y]'," the judges said in their ruling.
"This rule – the third-party doctrine – applies even when 'the information is revealed' to a third party, as it assertedly was here, 'on the assumption that it will be used only for a limited purpose and the confidence placed in the third party will not be betrayed'."
Thus, the court said, the CSLI information was legally collected and going forward, police can pull the tracking data without the need to first obtain a search warrant. The judge panel did note, however, that the Supreme Court and Congress could both create the need for a warrant should they expressly eliminate the third-party doctrine.
The next step in the case would be an appeal to the Supreme Court, which would decide whether to hear the arguments or remand the case to the appeals court. ®