An ACLU attorney on Wednesday urged the Supreme Court to rule that law enforcement authorities need a warrant to obtain cell phone records that reveal individuals' locations over a period of time.
"Nobody has expected ... in a free society that our longer-term locations will be aggregated and tracked," lawyer Nathan Wessler told the justices.
Wessler was urging the court to rule that the police should have sought a warrant before obtaining 127 days' worth of cell phone location records from Sprint and MetroPCS for Timothy Carpenter, a suspect in robberies in Michigan and Ohio. The prosecutors instead obtained court orders under the Stored Communications Act -- which doesn't require authorities to show they have probable cause to believe the records will yield evidence of a crime.
Justice Department attorney Michael Dreeben countered that a warrant wasn't required because the cell phone carriers were only asked to divulge routing information, as opposed to contents of any communications.
"People who dial phone numbers on calls know that they're being routed through a cell phone or a landline provider. Those records can be made available to the government," Dreeben told the court.
The closely watched battle, which could lead to new standards regarding digital privacy, drew the attention of a host of outside groups including Google, Facebook and Microsoft, which argued in a friend-of-the-court brief that digital data is entitled to "strong" protections against searches by the police.
The records obtained by the police in Carpenter's case placed him at the scene of the crimes. He was convicted of six robberies and sentenced to almost 116 years.
Carpenter unsuccessfully appealed to the 6th Circuit Court of Appeals, which ruled that the authorities didn't need a search warrant on the grounds that he lacked a "reasonable expectation of privacy" in records that were held by third parties -- his wireless carriers.
The 6th Circuit's decision drew on a Supreme Court case from 1979, when the court said police didn't need a warrant to obtain a list of phone numbers dialed by a suspect. The court ruled in that case that people have no reasonable expectation of privacy in the phone numbers they dial because they have shared that information with their telephone carriers.
More recent cases have called that reasoning into question. In 2014, the Supreme Court held that the police need a warrant before searching cell phones, and in 2012, the Supreme Court ruled that the police violated a suspect's rights by installing a GPS device on his car without a warrant.
Justice Elena Kagan suggested during Wednesday's argument that the police should have obtained a warrant for the same reasons they need a warrant to install a GPS device. "The obvious similarity is that, in both cases, you have reliance on a new technology that allows for 24/7 tracking" Kagan told Dreeben.
Justice Sonia Sotomayor also seemed inclined to rule that a warrant is required "The Constitution protects the rights of people to be secure. Isn't it a fundamental concept, don't you think, that that would include the government searching for information about your location every second of the day," she asked Dreeben.
He replied that warrants aren't necessary when people share data with a third party -- in this case, the phone carriers.
But not all of the justices seemed inclined to rule for the defense. Justice Anthony Kennedy asked Carpenter's attorney why the Stored Communications Act -- which authorizes judge to issue subpoenas for relevant information -- doesn't offer enough protections to defendants.
Justice Neil Gorsuch, the newset member of the Supreme Court, floated the theory that the location information was Carpenter's "property."
"Say a thief broke into T-Mobile, stole this information and sought to make economic value of it," Gorsuch said in an exchange with Carpenter's lawyer. Gorsuch followed up by asking whether Carpenter would have grounds to bring a civil suit against the thief.
While the battle over Carpenter's records centers on a search by the police, the court's decision could play a role in privacy cases involving tech companies. A 2014 court ruling requiring law enforcement authorities to obtain a warrant before searching cell phones was later referenced by consumers who brought a privacy lawsuit against Google and other companies.
A group of Safari users argued in that matter that Google and the other companies violated the federal wiretap law by circumventing their browsers' privacy settings in order to track the Web sites they visited for ad-targeting purposes. Google ultimately agreed to pay $5.5 million in order settle the litigation