Washington, D.C.—Cell phone location data, which can provide an incredibly detailed picture of people’s private lives, implicates our Fourth Amendment rights against unreasonable searches, requiring police to obtain a warrant to gain access, the Electronic Frontier Foundation (EFF) told the Supreme Court today.

Weighing in on separate cases where two courts have applied 1970s-era law to digital communications in the information age, EFF urged the nation’s highest court to step in and establish that Americans have the right to expect location data generated from their cell phones is private and protected by the Constitution against unreasonable searches and seizures.

Cell phones constantly connect to cell towers and antennas—which number in the hundreds of thousands—that handle traffic from an estimated 378 million U.S. cell phone accounts. The data generated about these connections, known as cell-site location information (CSLI), create a highly detailed picture of people’s private lives. We carry our cell phones when we leave our homes each day, when we walk into a therapist or lawyer’s office, visit a gun shop, attend a political meeting or sleep at a friend’s. Location information about these private activities is tracked and stored, for years, by cell service providers.

Defendants in U.S. v. Carpenter and U.S. v. Graham were convicted after police obtained, without warrants, hundreds of days of location data produced by their phones to connect them to crimes. The defendants maintained that the use of CSLI violated their Fourth Amendment rights. But the appeals courts in both cases followed Smith v. Maryland, a Supreme Court decision from 1979, when many Americans used rotary-dial land-line phones. In Smith, the Court said that people who voluntarily give certain information to third-parties—such as banks or the phone company—have no expectation of privacy in this information, and thus the government does not need a warrant to access it.

“Cell phone users don’t voluntarily provide location data to their providers—it happens automatically without their control and is generated whether or not the phone is being used,” said EFF Senior Staff Attorney Jennifer Lynch. “Other federal courts and judges in several states have recognized that the so-called ‘third party doctrine’ doesn’t apply to CSLI. It’s time for the Supreme Court to consider whether a decision it made before the existence of commercial cell phones, which are now ubiquitous and reveal our every move, can still be used to override Fourth Amendment protections.”

In 2014, the high court recognized in a unanimous ruling that the astounding amount of sensitive data stored on modern cell phones requires police to obtain a warrant before accessing data on an arrestee’s device. And in a landmark 2012 decision, the court held that GPS tracking is a search under the Fourth Amendment. Yet police are obtaining extensive historic cell-site information without warrants.

“CLSI can give law enforcement far more information about a person’s movement than GPS tracking—cell phones go everywhere their owners go,” said EFF Staff Attorney Andrew Crocker. “If GPS tracking implicates Americans’ Fourth Amendment rights, prolonged cell-site data collection—which provides sensitive details about where we went, who we met with, and what we did—should also be protected against warrantless searches. We’re asking the court to grant review of these important cases and address the Fourth Amendment privacy implications of CSLI.”

EFF filed identical petitions in U.S. v. Carpenter and U.S. v. Graham.

For the brief:

https://www.eff.org/document/eff-petition-graham-v-us

For more on these cases:

https://www.eff.org/cases/united-states-v-graham