The following was first published in Scientific American.
If, in the early 1980s, the U.S. government had proposed a new crime-solving program requiring every adult to carry a small device that not only performed location tracking but also recorded the phone numbers of all recent contacts, opposition would have been swift and indignant. Such a proposal would have been socially, politically and legally untenable given the standards of the day. Yet, by using mobile phones and GPS receivers, we are opting into systems that routinely gather our location data and often much more.
The question of whether police need a warrant to affix a GPS tracking device to a suspect’s vehicle has made it all the way to the Supreme Court, which begins hearing arguments today. A ruling is expected in the spring.