Washington D.C.—Americans have the right to expect that digital records of their daily travels—when they left home, where they went, and how long they stayed—is private information, the Electronic Frontier Foundation (EFF) said in an amicus brief filed with the Supreme Court of the United States.

Weighing in on one of the most important digital privacy rights cases of the year, EFF is asking the court to hear arguments in Davis v. U.S., a federal criminal case from Florida that examines whether police need a search warrant to obtain historical cell site location information (CSLI). These records show law enforcement which cell phone towers your phone has connected to in the past. In this case, police obtained 67 days of records about defendant Quartavious Davis without a warrant and used them to implicate him in various robberies.

In the brief filed Monday, EFF and other advocacy groups argue that the ubiquity of cell phone use in this country—along with a clear increase in law enforcement demands for cell site records and conflicting court rulings about the need for search warrants—means the U.S. Supreme Court should grant review in Davis’s case.

“It’s time for law enforcement to recognize that Americans’ physical location information is sensitive, and private, and protected by the Fourth Amendment’s guarantee against unreasonable searches and seizures,’’ said EFF Senior Staff Attorney Hanni Fakhoury. “Cell phones are an integral part of modern life and carry detailed information about where we go and when we travel. Many federal and state courts have already ruled that cell site information is protected under the Fourth Amendment. We are urging this country’s highest court to afford all Americans this important protection from law enforcement unless there’s a search warrant.’’

The request for Supreme Court review comes after the U.S. Court of Appeals for the Eleventh Circuit found Davis did not have an expectation of privacy in historical cell site records, meaning police did not need to obtain a search warrant before requesting and receiving his location data. This decision conflicts both with an earlier decision from the Florida Supreme Court, and a later decision from the U.S. Court of Appeals for the Fourth Circuit, which found people do have an expectation of privacy in these records, so police need a warrant to get them. More critically, the Eleventh Circuit’s decision ignores the modern reality of cell phone use: nearly everyone carries one, leaving a digital trail that could potentially be accessed at any time. Without a strong ruling from the highest court, the public and police are left with conflicting guidance about the level of constitutional protection for this sensitive location information.

“The U.S. Supreme Court has already ruled in Riley v. California that cell phones hold vast amounts of private information, potentially the sum of an individual’s private life, and searching that data requires a search warrant,’’ said EFF Senior Staff Attorney Jennifer Lynch. ‘’We believe it’s high time that the government recognize that cell phones not only hold our private data, they also generate data—stored with cell phone companies—about our private movements and travels. The government shouldn’t be allowed unfettered access to this information without first going to court and obtaining a warrant.’’