By Nate Freed Wessler, Staff Attorney, ACLU Speech, Privacy & Technology Project
In a tremendous step forward for our right to privacy under the Fourth Amendment, the Eleventh Circuit Court of Appeals has held in United States v. Quartavious Davis that police need a warrant to obtain historical cell phone location information from a cell service provider. The ACLU filed an amicus brief in the case, along with the ACLU of Florida, Electronic Frontier Foundation, Center for Democracy & Technology, and National Association of Criminal Defense Lawyers. In April, I argued the cell phone tracking issue before a three-judge panel of the court.
This ruling is the first time a federal appeals court has held that the Fourth Amendment requires a warrant when police seek cell phone location records from carriers. As the court concluded: “In short, we hold that cell site location information is within the subscriber’s reasonable expectation of privacy. The obtaining of that data without a warrant is a Fourth Amendment violation.”

We have previously explained just how invasive the cell phone tracking was in this case: law enforcement obtained 67 days’ worth of historical cell phone location records about the defendant, which revealed more than 11,000 individual location points. The court recognized the sensitivity of this data, writing that

the exposure of the cell site location information can convert what would otherwise be a private event into a public one. When one’s whereabouts are not public, then one may have a reasonable expectation of privacy in those whereabouts.

Thus, the court continued,

even one point of cell site location data can be within a reasonable expectation of privacy. . . . There is a reasonable privacy interest in being near the home of a lover, or a dispensary of medication, or a place of worship, or a house of ill repute.

The court also rejected the government’s argument that people lose their privacy interest in their location data merely by signing up for cell phone service and using their phone. Agreeing with the Third Circuit’s view on this question, the court held that the defendant “has not voluntarily disclosed his cell site location information to the provider in such a fashion as to lose his reasonable expectation of privacy.” In support of this conclusion, the court relied on the government’s own words:

The prosecutor stated to the jury “that obviously Willie Smith, like [Davis], probably had no idea that by bringing their cell phones with them to these robberies, they were allowing [their cell service provider] and now all of you to follow their movements on the days and at the times of the robberies . . . .”

“Just so,” wrote the court.
By rejecting application of the so-called “third party doctrine” in this context, the court offers a serious defense of the vitality of Fourth Amendment privacy rights in the digital age.
Sadly, the Eleventh Circuit’s opinion does not benefit the defendant in the case, because the court determined that law enforcement relied in good faith on the decision of a magistrate judge to issue an order authorizing the cell phone tracking. (The order was issued pursuant to a provision of the Stored Communications Act under a low relevance and materiality standard). Mr. Davis’s unconscionable longer-than-life sentence will stand.
But in future cases, the government is now on notice that it must get a warrant before obtaining cell phone location information. The court’s opinion is binding law within the Eleventh Circuit, which comprises Florida, Georgia, and Alabama. Elsewhere in the country it should constitute persuasive authority, joining similar opinions from the New Jersey and Massachusetts Supreme Courts. Cases raising the same issues are now on appeal to the Fourth and Sixth Circuits, and more will soon follow elsewhere in the country.
The court’s unequivocal opinion should also provide guidance to lawmakers grappling with electronic privacy issues. Across the country, states have been considering legislation to require a probable cause warrant before law enforcement tracks location in criminal investigations. The biggest sticking point this legislative session has been whether those bills should cover historical and real-time location information, or just real-time tracking. There are a number of sound public policy reasons why legislatures should adopt comprehensive bills, and the Eleventh Circuit’s decision provides a persuasive explanation of why the Fourth Amendment requires that outcome. Legislators now have the opportunity to lead by enacting privacy protections for their constituents—even before abuses reach their courthouses.
This post originally appeared on ACLU National's Blog of Rights.