Without a doubt, driverless cars (and perhaps aircraft and their imminent arrival) will bring a new set of problems, questions, and -- of course -- legislation. Peter Wayner discusses some aspect in this video at SlashDot.
The idea of data gathering is integral to robot-driven cars. The U.S. Congress is moving forward with legislation on just such a concept.
Florida, Nevada, and California have passed laws to make self-driving cars street legal, thanks in large part with help from lobbying efforts by Google. In Europe, simpler versions (not 100% autonomous) is already going through the initial phases of exploration, and the EU is beginning to address the legal difficulties.
But some issues seem intractable. The Geneva Convention on Road Traffic (Did you know there was one? From 1949) requires that drivers "shall at all times be able to control their vehicles," and provisions against reckless driving usually require "the conscious and intentional operation of a motor vehicle." Some of that may be semantics, but other concerns are harder to dismiss. After a crash, drivers are legally obligated to stop and help the injured. What do you do if there's no one in the car?
See info about Peter Wayner's forthcoming book (the table of contents).