Cell signal: What high court ruling may mean for future of digital privacy

In a 5-to-4 decision today, the US Supreme Court updated privacy protections in the digital age, ruling that historic location data collected by from individual cellphones is protected by the Fourth Amendment of the Constitution.

Given the routine advancement in communications technologies, especially in recent years with the proliferation of smartphones, the Fourth Amendment protection against unreasonable searches by the government has been one of the most routinely reinterpreted constitutional amendments. The decision this morning – in which Chief Justice John Roberts sided with the court’s four left-leaning justices – continues that trend, and reinforces suspicions the high court has voiced in the past about how rapid technological advancements could implicate personal privacy.

Chief Justice Roberts was careful to detail the narrow parameters of the majority’s decision in his 27-page opinion. Nevertheless, four separate dissenting opinions totaling 92 pages suggests that lower courts now have a significant task ahead of them tackling the many questions the decision is likely to raise.

“It’s a gigantic decision for Fourth Amendment jurisprudence,” says Christopher Slobogin, director of the Criminal Justice Program at Vanderbilt Law School. “It is in large part a result of the court’s realization that technology is changing the relationship between the government and its citizens.”

“If read broadly, [the decision] could have a huge impact on law enforcement,” he adds, but “the majority is careful to limit its decision, and lower courts can draw distinctions between this case and other cases.”

'Seismic shifts' in technology

The case concerns the arrest and conviction of Timothy Carpenter, who led a string of cellphone store robberies in Michigan and Ohio in 2010. Law enforcement was able to place him near the scenes of the robberies when they occurred in part by collecting 127 days of Mr. Carpenter’s cell-site location information from cell towers operated by MetroPCS and Sprint – information they were able to obtain under a law requiring them to show only that the data was “relevant and material” to the ongoing investigation. 

Carpenter argued that such a vast swathe of data was protected by the Fourth Amendment – thus requiring law enforcement to show probable cause that he was involved in a crime before being able to seize it. Lower courts had ruled against him in part because the data had been seized from a third party, and because he had “voluntarily” given it to them by using his cellphone. Today, five Supreme Court justices instead agreed with Carpenter.

The specific facts of the case are important because the majority opinion refuses to look beyond them. 

“Our decision today is a narrow one,” Chief Justice Roberts wrote in the majority opinion. Essentially: the decision expands Fourth Amendment protections to a week or more of cell-site location information and no further. The questions of whether such information collected for a shorter period, or in real time, for example, were left for another day.

Roberts nevertheless voiced serious concerns about “the seismic shifts in digital technology” presented in the case, and about both the current and future potential for abuse if the government is able to collect a week or more of a person’s location data without having to show probable cause.

Comparing a modern cellphone to an ankle monitor in how precisely they each track the users’ movements, he wrote that the government is able to “travel back in time to retrace a person’s whereabouts,” adding that with 400 million devices in the country constantly pinging their location to cell towers “this newfound tracking capacity runs against everyone,” not just those under investigation.

“This case is not about ‘using a phone’ or a person’s movement at a particular time,” he added. “It is about a detailed chronicle of a person’s physical presence compiled every day, every moment, over several years.”

Significantly, the decision factored in how the technology has advanced since Carpenter’s arrest in 2010. Back then, investigators were only able to place in a sector ranging from one-eighth to four square miles. Today, wireless carriers can pinpoint a phone’s location within roughly 50 yards.

That could pave a way for the Fourth Amendment to be expanded to protect other kinds of data, says Jennifer Lynch, a senior staff attorney for the Electronic Frontier Foundation, which supported Carpenter in the case.

“There is a lot of this case that could apply to third-party tracking of other parts of our lives,” she says. “It recognizes that we can have a reasonable expectation of privacy in records we share with third parties” – records such as emails and smart meters in homes. 

Impact on law enforcement

The four dissenting justices voiced several complaints and concerns. Justice Anthony Kennedy, joined by Justices Clarence Thomas and Samuel Alito, wrote that the court should have maintained “relevant Fourth Amendment precedents and principles,” such as constitutional protections not extending to personal information held by third parties or given up voluntarily by an individual.

Furthermore, Justice Kennedy added, the decision “will undermine traditional and important law enforcement practices; and will allow the cell phone to become a protected medium that dangerous persons will use to commit serious crimes.”

Lawrence Rosenthal, a professor at Dale E. Fowler School of Law at Chapman University in Orange, Calif., agrees. The fact the high court has written a decision based in part on how technology could evolve in the future means “the specter of whether the government’s going to go after all our information” has taken precedence over “sophisticated [police] work.”

“What we wind up with is a choice between a conceptual or a pragmatic Fourth Amendment. And I’d say the conceptual fourth amendment is winning,” he adds.

Unanswered questions

The Fourth Amendment has always been interpreted somewhat conceptually, however. Originally it only considered “houses, papers and effects” subject to these kinds of privacy protections. In the 19th century, after the postal service was established, it was expanded to include the contents of mail, and in the 1970s it was expanded again to include the contents of telephone conversations. 

For the short-term, the Supreme Court has kept its decision narrow to try and avoid significant disruption. Requiring law enforcement to get a probable cause warrant only if they want to collect a week or more of location data is one example of that. Police could – and currently do, according to what Professor Slobogin says cops have told him – collect just a few days-worth of location data and use that to prove probable cause and get a warrant for longer surveillance. 

Other unanswered questions will have to be hashed out over time in the lower courts, however. 

As Kennedy queried in his dissent, limiting the decision to just long-term cell-site location data means the court has also “held that individuals do not have a reasonable expectation of privacy in financial records” or records of who a person calls – information that “dwarfs what can be gathered from cell site records.” 

For now, however, the high court has taken a notable step by acknowledging the new challenges technological advancements are posing for individual privacy.

“You didn’t used to be able to carry your entire life in your pocket, and now you can,” says Slobogin.

“Roberts is realizing technology is changing the name of the game,” he adds, “and it’s high time the court made this recognition.”

Staff writers Peter Grier and Harry Bruinius contributed reporting to this story. 

Correction: Chapman University is located in Orange, Calif.