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Privacy win: Cops need a warrant to track your cellphone location

Jun 13, 20143 mins
Big DataData and Information SecurityMicrosoft

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If you have your cellphone on you, then it constantly pings against the closest tower, whether you are using it or not. Cops and the government regularly use that cellphone location data without a warrant. But in Florida, Georgia, and Alabama, tapping into that location data without a warrant is now illegal.

“We hold that cell site location information is within the subscriber’s reasonable expectation of privacy,” a three-judge panel of the 11th U.S. Circuit Court of Appeals in Florida recently decided (pdf). “The obtaining of that data without a warrant is a Fourth Amendment violation.”

The case involves the conviction of Quartavious Davis for armed robberies in Miami, a conviction based on cellphone location data that the government obtained from a wireless carrier without a warrant. Instead of proving probable cause for a warrant, the Miami U.S. Attorney got a “D-order” for location data deemed “relevant and material” to an investigation. In fact, the cops got 11,606 location records for Davis, which averaged out to about 173 points per day. That’s just crazy –  over-the-top tracking – and although the conviction held, as did Davis’s 162-year sentence, the court put its foot down in a big privacy win.

Judge David Sentelle wrote (pdf):

The United States further argues that cell site location information is less protected than GPS data because it is less precise. We are not sure why this should be significant. We do not doubt that there may be a difference in precision, but that is not to say that the difference in precision has constitutional significance. While it is perhaps possible that information could be sufficiently vague as to escape the zone of reasonable expectation of privacy, that does not appear to be the case here.

The prosecutor at trial stressed how the cellphone use of the defendant established that he was near each of six crime scenes. While committing a crime is certainly not within a legitimate expectation of privacy, if the cell site location data could place him near those scenes, it could place him near any other scene. 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. Again, we do not see the factual distinction as taking Davis’s location outside his expectation of privacy. That information obtained by an invasion of privacy may not be entirely precise does not change the calculus as to whether obtaining it was in fact an invasion of privacy.

“The court’s opinion is a resounding defense of the Fourth Amendment’s continuing vitality in the digital age,” ACLU attorney Nathan Freed Wessler said. “This opinion puts police on notice that when they want to enlist people’s cellphones as tracking devices, they must get a warrant from a judge based on probable cause. The court soundly repudiates the government’s argument that by merely using a cellphone, people somehow surrender their privacy rights.”

Additionally, the government has argued that the NSA’s warrantless metadata collection program is legal because customers’ phone records are business records and therefore not private. The Eleventh Circuit opinion may help prove that NSA metadata collection does violate peoples’ expectation of privacy, despite customers’ records also being business records. The ruling, according to Jennifer Granick, civil liberties director at the Stanford Center for Internet and Society, “has taken a giant step away from the legal justification propping up many of the government’s targeted and bulk metadata collection practices.”

ms smith

Ms. Smith (not her real name) is a freelance writer and programmer with a special and somewhat personal interest in IT privacy and security issues. She focuses on the unique challenges of maintaining privacy and security, both for individuals and enterprises. She has worked as a journalist and has also penned many technical papers and guides covering various technologies. Smith is herself a self-described privacy and security freak.