Of the thousands of separate requests web and telecommunications companies get each year for customer data, many probably never directly crack a case. But sometimes, they do. Ars Technica discusses the case of the High Country Bandits, two rural bank robbers who were caught by an electronic dragnet known as a "cell tower dump." The FBI asked carriers to turn over the records of every phone that had come near cell towers close to the locations of the robberies at a certain time.

Officers successfully got two suspects from the data, finding one number that had been at all four sites at the right time and a second that had been at two — and was in contact with the first number. But in the process, it looked over the records of more than 150,000 other numbers. Did the ends justify gathering the data with a court order? Or should the location data have been considered a search under the Fourth Amendment, requiring a warrant and a higher burden of proof?