In the United States v. Jones “five Supreme Court justices held that a man’s reasonable expectation of privacy was breached after police tracked his movements on public roads for 28 days using a GPS device.” The case has spurred research on surveillance more broadly:
Using the Jones ruling as a baseline, [Kevin] Bankston and [Ashkan] Soltani calculated and compared the costs of different location tracking methods used by police. Traditional surveillance methods like covert foot and car pursuits cost $250 and $275, respectively, per hour per target, according to their estimates. Another common method, which the Supreme Court has approved, involves two agents tracking a suspect’s movements from their police vehicle through a radio-based transmitter affixed to a target’s car or slipped in his bag at a cost of $105 to $113 per hour.
Newer surveillance technologies were significantly cheaper, they found.
The total price tag of tracking a suspect using a GPS device, similar to the one in Jones, for instance, came out to $10 an hour over one day, $1.43 per hour over a week and $0.36 per hour over a month. Another relatively new technique, obtaining a suspect’s location through his or her cellphone signal with the carrier’s assistance, yielded similar results. As of August 2009, fees for obtaining cellphone location data from carriers ranged from $0.04 to $4.17 per hour for one month of surveillance. After tabulating their results, Bankston and Soltani concluded that the total cost of using a GPS device to track a suspect over 28 days (the method rejected in Jones) was roughly 300 times less expensive than the same tracking using a transmitter (technology approved by the Supreme Court) and 775 times less expensive than using the five-car pursuit method (also approved). Meanwhile, the cost of using transmitter-surveillance technology was only 2.5 times less expensive than undercover car pursuit.