The U.S. Circuit Court for the District of Columbia offered some new judicial insight into reasonable expectations of privacy when it issued a ruling this month overturning the conviction of an alleged drug trafficker because the prosecution used evidence gathered via a global positioning system (GPS) device placed on the man's car and monitored over a month-long period. The police placed the GPS tracking device without first obtaining a warrant, following a legal precedent (from the 1983 Supreme Court decision in United States v Knotts) that no warrant was required to use such a device to track a suspect on a single journey from an origin to a destination. The lawyers for Antoine Jones, the convicted man in this case, argued successfully that by "tracking his movements 24 hours a day for four weeks with a GPS device they had installed on his Jeep without a valid warrant" the police violated Jones' 4th Amendment protection against unreasonable search. On its face the ruling seems to contradict precedents from at least three other federal courts where warrantless use of a GPS device is concerned, at least in terms of putting a temporal constraint on the duration of the monitoring in question.
The underlying logic of the Knotts decision was that since a trip on public thoroughfares is by definition in plain view of the public, no one could reasonably claim an expectation of privacy applied to the trip, including the route taken or the destination. In contrast, where continuously monitoring was involved with Jones, the DC Circuit panel noted that "the whole of one‘s movements over the course of a month is not actually exposed to the public because the likelihood anyone will observe all those movements is effectively nil."
The prosecution working to convict Jones relied on the aggregate information gathered over numerous trips (correlated with cell phone calls and other intercepted communications that were obtained with the use of warrants) to develop a pattern of Jones' movements that sufficed to convince the jury that he was engaged in cocaine trafficking. The prosecution had no direct evidence on Jones (such as possession of drugs), so the appellate court determined that without the GPS data the prosecution could not have secured a conviction, and therefore reversed it because the evidence was obtained in violation of the 4th Amendment.
Aside from the 4th Amendment implications of the ruling, the decision has raised a number of questions about the applicability of existing laws and judicial precedent to uses of new technology, particularly those that involve geo-location information. A judicial opinion that prolonged monitoring of user movements could constitute a search and, if performed by a government entity, therefore fall under the provisions of the 4th Amendment, open up speculation about implications for social networking applications such as Foursquare,
Twitter, and Facebook that can incorporate user locations based on information associated with the computers or mobile devices used to access them. On a different technological front, new concerns have been raised recently about the use of uniquely identifiable RFID transmitters — such as those used in many late model cars to communicate tire pressure to onboard automotive computers — and the potential for the RFID chips to be used to track user location and movements. The consistent theme in all these instances is the ability of technology to outpace legal, regulatory, and policy provisions about what uses of these technologies are acceptable, and how to guard against technically feasible unintended or surreptitious activities these technologies enable.