Skip to main content

Supreme Court: Government Must Get Warrant For Smartphone Location Data

The Supreme Court ruled in a 5-4 decision that law enforcement will no longer be able to access troves of smartphone information about citizens, such as carriers' location data, without a warrant. The ruling is a major win for privacy activists, such as the ACLU and EFF, who have been fighting against law enforcement’s practice of obtaining smartphone data covering many months or years.

Carpenter v. United States

In the Carpenter v. United States case, the prosecutor suspected that Timothy Ivory Carpenter was involved in an armed robbery. Witnesses said that Carpenter had planned the robbery and was waiting in a stolen car across the street as the robbery happened. Afterwards, the prosecutor obtained 127 days of smartphone location data, as well as other records, from the wireless carriers, that showed that Carpenter was indeed in the area when the robbery happened. Following this information, Carpenter was convicted and sentenced to 116 years in prison.

Carpenter later accused the government of violating his constitutional rights, because the smartphone data they obtained over that four-month period also revealed when he had slept at home on certain nights or when he had attended church on Sunday mornings. Carpenter’s lawyers argued that he had an expectation of privacy, which the government violated by not obtaining a warrant from a judge before getting so much location data.

However, prior to this case reaching the Supreme Court, the Six Circuit Court ruled that Carpenter didn’t have an expectation of privacy because he voluntarily gave that information to the wireless carriers. Therefore, the court argued, the government could obtain his location data without a warrant.

The Six Circuit Court seems to have applied the “Third-Party Doctrine,” a legal theory that says that if you give your data to another party, then you can no longer expect that data to remain private.

Supreme Court Ruling

In the 5-4 vote, the majority of justices disagreed with the Six Circuit Court, primarily because the government had obtained large amounts of data about Carpenter’s whereabouts over an extended period of time. 

Chief Justice Roberts, who was part of the majority that wrote the ruling, said the following:

“Mapping a cell phone’s location over the course of 127 days provides an all-encompassing record of the holder’s whereabouts.

As with GPS information, the timestamped data provides an intimate window into a person’s life, revealing not only his particular movements, but through them his ‘familial, political, professional, religious, and sexual associations.”

The newly appointed justice Gorsuch was one of the dissenters, but not because he wanted law enforcement to get cell-site location data without a warrant. Instead, he argued that the majority’s ruling didn't go far enough.

In his opinion, the standard of having a “reasonable expectation of privacy” in a given context sets the bar too low for Americans’ constitutional rights. Furthermore, even if users offer data voluntarily to third-parties, Gorsuch argued that it doesn’t mean the government can just come and take that data without a warrant, as the Fourth Amendment would still apply.

An excerpt from his dissenting opinion notes:

“What’s left of the Fourth Amendment? Today we use the Internet to do most everything. Smartphones make it easy to keep a calendar, correspond with friends, make calls, conduct banking, and even watch the game. Countless Internet companies maintain records about us and, increasingly, for us.

Even our most private documents—those that, in other eras, we would have locked safely in a desk drawer or destroyed—now reside on third party servers. Smith and Miller teach that the police can review all of this material, on the theory that no one reasonably expects any of it will be kept private. But no one believes that, if they ever did.”

A brief filed by Apple, Google, and Facebook also warned the justices against defaulting their opinions to the Third-Party Doctrine

“No constitutional doctrine should presume that consumers assume the risk of warrantless government surveillance simply by using technologies that are beneficial and increasingly integrated into modern life.”

Big technology companies likely believe that if their users could trust that their data is safe on their servers and that the government doesn’t abuse its powers, then those users may be more willing to share that data with them. The Supreme Court ruling should restrict how much data the government can obtain from companies without a warrant, but it remains to be seen how well this will be applied in practice.

Lucian Armasu is a Contributing Writer for Tom's Hardware US. He covers software news and the issues surrounding privacy and security.