The U.S. Supreme Court signaled Wednesday it may be open to new limits on the government's ability to track someone's movements by accessing data on that person's cellphone.
A case before the high court could result in a landmark decision in the ongoing debate over civil liberties protections in an era of rapid technological change.
At issue is whether law enforcement will be able to access cellphone data that can reveal a person's whereabouts without having to first obtain a court-issued search warrant.
The case stems from the conviction of Timothy Carpenter for a series of robberies back in 2010 and 2011. Prosecutors were able to obtain cellphone records that indicated his location over a period of months, information that proved crucial to his conviction.
Get a warrant
On Wednesday, lawyers for the American Civil Liberties Union argued that law enforcement should be required to obtain a court-ordered search warrant before obtaining such information.
They also argued that allowing law enforcement to access the cellphone data without a warrant would violate the prohibition on unreasonable search and seizures contained in the Fourth Amendment to the U.S. Constitution.
"It is impossible to go about our daily lives without leaving a trail of digital breadcrumbs that reveal where we have been over time, what we have done, who we spent time with," said ACLU attorney Nathan Freed Wessler, who spoke to reporters outside the Supreme Court following oral arguments. "It is time for the court, we think, to update Fourth Amendment doctrine to provide reasonable protections today."
Some of the justices also raised concerns about privacy in the digital age.
"Most Americans, I think, still want to avoid Big Brother," Justice Sonia Sotomayor, who often sides with the liberal wing of the court, said.
Chief Justice John Roberts, who often sides with conservatives on the court, said the central question was whether the cellphone information should be accessible to the government "without a warrant."
Privacy versus security
Justice Department lawyers defended the process of obtaining the data without a court warrant, arguing that even though the technology has changed, the need to rapidly obtain such information for law enforcement has not. The government also argued that privacy rights are not at issue because law enforcement agencies can obtain information from telecommunications companies that record transactions with their customers.
Justices Samuel Alito and Anthony Kennedy indicated they were open to the government's position in the case.
Legal experts say whichever way the court eventually rules could have an enormous impact on privacy rights in the digital age.
"I don't think that this is a world that anybody anticipated a couple of decades ago," Stanford University law professor David Alan Sklansky said via Skype. "These new data capabilities are rapidly increasing the things that government can do for good and for evil. And figuring out how we allow the government to make full use of these new capabilities, without endangering political liberties and endangering the privacy that is necessary for us to have the kind of flourishing democratic social life we want, is a huge ongoing challenge."
Sklansky added that the United States "has historically been a leader in thinking about privacy rights, particularly with regard to privacy from the government."
And he predicted that other countries will be closely following the high court case as they wrestle with similar conflicts. "This is a global problem. Countries around the world are trying to figure out how to deal with it. I think that people in all democratic countries should care about how the United States winds up resolving this question," he said.
Twice in recent years the Supreme Court has ruled in major cases related to privacy and technology and both times ruled against law enforcement.
The court ruled in 2012 that a warrant is required to place a GPS tracking device on a vehicle. And in 2014, the high court ruled that a warrant is required to search a cellphone seized during an arrest.
A decision in the current case, known as Carpenter v. U.S., is expected sometime before the end of June.