The Supreme Court has unanimously ruled that a warrant is necessary to use GPS when tracking suspects in a criminal investigation, following the overturned lifetime prison sentence of Washington, D.C. nightclub owner Antoine Jones. Jones was arrested back in January of 2008 for a narcotics charge after a GPS device was installed on his Jeep without permission or knowledge; the police tracked his movements 24 hours a day for several weeks prior to the arrest. Jones was initially sentenced to life in prison, but a federal appeals court overturned the conviction and the Supreme Court sided with the decision.

All nine Supreme Court judges agreed that the secret GPS tracking was a clear violation of Jones' fourth amendement rights against unreasonable search and seizure, with Associate Justice Antonin Scalia saying that "officers encroached on a protected area" when installing the GPS unit. While it's good to have it in writing that the police can't go around slapping GPS units on cars whenever they please, cases like this may continue to be an issue thanks to the proliferation of GPS-enabled devices people carry with them daily — Justice Samuel Alito wanted the court to go further and deal with the proliferation of GPS tracking on mobile devices. Hopefully it won't take a similar court case for our mobile devices to be protected as well.