It just got a bit harder for law enforcement agencies to turn your cell phone into a personal homing beacon: A federal court has slapped down the Justice Department's appeal of a February ruling that required investigators to seek a probable cause warrant before acquiring historical records of a cell phone users physical movements.
The government cited precedent suggesting that the use of tracking technology did not amount to a Fourth Amendment search when it disclosed no more than could be gleaned from physical surveillance of a target in public places—as when a tracking beacon is attached to an automobile on public highways. Because cell tower data provides only a very approximate location, they contended, it did not permit the sort of detailed tracking that would permit authorities to follow targets' movements in protected private spaces. Moreover, Justice Department attorneys argued, the Supreme Court has ruled that information voluntarily disclosed to third parties—as when customers provide the phone company with a dialed number—falls outside the ambit of the Fourth Amendment. Therefore, according to the government, the court should refrain from imposing a standard higher than specified by statute.
The court, however, appears to have been more persuaded by EFF and amici, who distinguished cell location data from automobile beacons, noting that it would permit law enforcement agencies to make inferences about the movements of persons — as well as about who was in possession of the phone at any given time — whether in public or private spaces. Moreover, they argued, a lax standard for seeking location data "enables dragnet surveillance" by permitting the government to acquire location records in bulk, then hunt for a particular pattern of movements. Though amici conceded that the government hadn't attempted such dragnet surveillance in the instant case, they warned that cell phone tracking is "ripe for such use."
I'm impressed that Digg had this and Reddit didn't. Guess all the holier-than-thou "cognoscenti" on Reddit won't stoop to reading Ars Technica, eh?