Imagine your car telling you exactly how long a traffic light will stay green, warning you if you wonÕt make it in time. Or imagine that same traffic light communicating with your car to inform you that some other vehicle is likely to run a red light. Imagine having the car in front of you tell your car that it is suddenly braking for an emergency, communicating faster than you could see and react to the illumination of its brake lights. These are the potential benefits of new Vehicle Safety Communication technologies.

Now, imagine your car as a node in a wireless network, constantly making connections and communicating with other nearby cars and roadside infrastructure. Imagine your car, as part of this peer-to-peer network, openly transmitting its location, speed, and identity to anyone with a receiver within 1000 meters, 10 times per second, every second your car is on. Compared to electronic toll collection systems, where a carÕs RFID tag is only activated and read when you happen to pass through a toll booth, imagine someone able to set up a wide-range data receiver to record the message activity of every single car that passes within a mile radius Ð or a government agency outfitting vehicles to drive throughout New York City to record the messages of all vehicles. These are some of the potential threats of new Vehicle Safety Communication technologies.

Vehicle safety communication (VSC) technologies are intelligent, in-vehicle safety applications designed to provide real-time information about the actions of nearby vehicles, potential road hazards, and ultimately the prediction of dangerous scenarios or imminent collisions. VSC applications rely on the creation of autonomous, self-organizing, peer-to-peer wireless communication networks Ð so-called ad-hoc networks Ð connecting vehicles with roadside infrastructure and with each other. In these networks, vehicles transmit, collect and process data with each other to provide information about the immediate surroundings; data messages, which are automatically transmitted by your car 10 times per second, include such information as your carÕs location, speed and telemetry data, and a vehicle identification number.

As the technical standards and communication protocols for VSC technologies are still being developed, certain ethical implications of these new information technologies emerge. Coupled with the predicted safety benefits of VSC applications is a potential rise in the ability to surveil a driver engaging in her everyday activities on the public roads. This problem of "privacy in public" has become an important focus for privacy theorists studying the ethics of information technologies. Developments in information technology mean that there is virtually no limit to the amount of information that can be recorded, virtually no limit to the level of data analysis that can be performed, information can be shared with ease, and virtually stored forever. All these separate pieces of personal information can now be processed, aggregated and analyzed in order to create a profile of oneÕs daily activities. The consequence of the emergence of such powerful information technology as VSC is a rise in the magnitude, detail, thoroughness and scope of the ability to surveil everyday people engaging in their everyday, public activities; this new information technology threatens oneÕs "privacy in public."

This paper will explore how the design of new VSC technologies might threaten oneÕs "privacy in public." It will consider how the introduction of such new information technologies might disrupt the existing norms of information appropriateness and information distribution in the context of highway travel, what Helen Nissenbaum calls the "contextual integrity" of personal information flows. Existing norms of information appropriateness in the context of highway travel anticipate the sharing of some general, visually observable information: non-identifiable information about a vehicleÕs occupants, the type of vehicle, observable information about where the vehicle is going, and the vehicleÕs license plate number. The added precision and accuracy of VSC technologies upsets the current norm of only appropriate visual information.

The norms of information distribution in the context of highway are materialized as natural barriers preventing the widespread distribution of personal information: the flow of information is generally confined to the likelihood that a person happens to be located in a particular spot in order to observe another vehicle. Further, that person would be unable to observe all vehicles and would have to selectively choose which vehicle to examine more closely for determining occupants, type or license number. It also is unlikely that any one observer would be able to maintain complete surveillance of a particular vehicle as it travels through chaotic rush hour traffic or travels hundreds of miles across country. VSC technologies have the potential to disrupt the natural barriers that previously limited the ability to track individual vehicles over space and time. Rather than a single piece of information being observed by a person that just happens to be at the right place at the right time, VSC technologies might allow information to be gathered and consolidated on a large scale and across a large area. All that is needed is a well-placed receiver and information for all passing vehicles can be recorded; or a series of well-placed receivers could collect information from the same vehicle over a span of miles. The digital nature of the information provided by VSC applications expands the ability to process, store and distribute vast amounts of personal information about individual vehicles, further disrupting the norms of information distribution.