Relying On 'Seismic Shifts In Digital Technology,' Supreme Court Requires Probable Cause For Historical Cellphone-Location Data

On June 22, 2018, in Carpenter v. United States, a divided Supreme Court (5-4) held that, under the Fourth Amendment, the government will generally need a search warrant to obtain cellphone-location data from service providers.  In Carpenter, the government had requested historical cellphone-location data from the service provider.  That data included very specific information about its user’s movements, as cellphones regularly connect with the closest cell tower and service providers maintain that information. 

The government obtained that data under §2703(d) of the Stored Communications Act, which requires the government to show “that there are reasonable grounds to believe that the … information sought [is] relevant and material to an ongoing criminal investigation.”  The “reasonable belief” standard is lower than the probable-cause standard required to obtain a search warrant under the Fourth Amendment.

The data revealed that the defendant’s phone was near the location of the charged crimes while they were occurring.  The government used that evidence at trial, and it obtained convictions, including one against Carpenter.

The issue before the Supreme Court was whether the government should have obtained a search warrant under the Fourth Amendment instead of relying on the “reasonable belief” standard of  § 2703(d) of the Stored Communications Act.  Chief Justice John Roberts joined by the Justices Ginsburg, Breyer, Kagan, and Sotomayor, held that the government must generally obtain a search warrant.

The closely watched case is a win for privacy advocates.  There are three key takeaways.

First, the Court rejected the government’s reliance on the third-party doctrine.  Under that doctrine, individuals have no reasonable expectation of privacy over information that they voluntarily disclose to third parties—here, cell-service providers.  In rejecting that argument, the Court relied on the “unique nature” of the data at issue.  The Court explained that, given the realities of modern technology, carrying a cellphone is “indispensable to participation in modern society.”  And by carrying a cellphone, one has no choice but to share location information with cell-service providers.  Therefore, such disclosures are not voluntary for purposes of waiving one’s reasonable expectation of privacy.   

Second, in contrast to the information at issue in prior third-party-doctrine cases, the Court stressed that historical cellphone-location data is “detailed, encyclopedic, and effortlessly compiled.”  Without Fourth Amendment protection, the government’s access to such a “detailed chronicle of a person’s physical presence compiled every day, every moment, over several years” would “implicate[] privacy concerns far beyond” the intrusions that courts had  considered in those prior cases.

Third, the Court emphasized that its holding was “a narrow one.”  The Court expressly reserved judgment on “matters not before us,” such as obtaining real-time, cellphone-location data.  The Court also explained that the government may still obtain such data without a warrant when there are sufficient exigent circumstances or when the government seeks data for a period shorter than that at issue in this case—seven days.

Given the significant questions that the Court has left unaddressed, companies providing remote-computing or electronic-communication services should carefully evaluate the privacy concerns set forth in Carpenter before responding to a request under § 2703(d).   The same privacy concerns can also extend beyond historical cell-location data to other industries that track and maintain extensive personal information.