Location privacy generally, and cell site tracking specifically, have been two hot issues this year, particularly since the Supreme Court's January ruling in United States v. Jones that installing a GPS device on a car without a search warrant violated the Fourth Amendment. After Jones, we were optimistic that both courts and legislatures would begin to take location privacy seriously and demand warrants before granting law enforcement access to a map of our every movements over an extended period of time. But it hasn't turned out that way. In August, the Sixth Circuit Court of Appeals issued a very bad decision (PDF), ruling law enforcement did not need a search warrant to track a cell phone in real time.

So this week EFF and a number of other civil liberties organizations joined together in an amicus brief to ask the Sixth Circuit to reconsider its decision. The Sixth Circuit heard argument in the case just a few days before the Supreme Court issued its opinion in Jones. Without the benefit of an in-depth discussion of the impact of that critical decision, the Sixth Circuit's opinion naturally failed to appreciate the changing legal landscape in gutting privacy protections for millions of people.

Privacy advocates, including EFF, recognized this as a dangerous and troubling result. In our amicus brief filed Tuesday, we note that cell phone tracking is even more intrusive than the GPS tracking involved in Jones. A GPS device affixed to a car really follows the car, which is a proxy for someone's location only some of the time. But most people carry their phones in their pockets or purses wherever they go, including their homes. Cell phone tracking thus enables true, round the clock 24/7 tracking of an individual in a way a physical GPS installed on a car is unable to do.

We hope the Sixth Circuit will reconsider its earlier decision, particularly as more courts begin to weigh on in the issue. The Fifth Circuit Court of Appeals will hold oral argument on the issue of warrantless cell site tracking on October 2 in a case where we filed an amicus brief. We'll be there in court to personally argue in favor of a warrant requirement, and we'll definitely be telling the court to not follow the Sixth Circuit's misguided opinion.