From the comp.risks Usenet group comes this thought provoking piece from Lauren Weinstein.
The main thing you should know about autonomous vehicles is that they are utterly inevitable.
Leaving aside technical, financial, and cultural issues for the moment, the question I'd really like to see us thinking about now -- before we really need the full answers -- is how we're going to prevent mass government abuse of these vehicles.
The amount of video and other data these vehicles will be collecting will be immense. You can bet governments will want it, both in individual cases and en masse. Governments will want to know where every car is or was, every moment. They will make license plate scanners totally obsolete.
They will want remote control capabilities. Whether or not vehicles can be started. Whether they will keep running or automatically pull over to the side of the road to await a police vehicle (or drive into the nearest police station, with the windows and doors locked?) if they believe a suspect is inside. Whether or not you can drive if you haven't been paying your bills or are having a legal dispute. They will want the ability to block all vehicles from areas where they don't want to be observed, and shoo all vehicles already there out of the area. This means individual and en masse remote control. Pretty powerful stuff.
And remote control is likely to come irrespective of law enforcement, because it's the most practical way to deal with situations beyond the scope the car's AI (unusual weather or road conditions, accident and construction sites with authorities giving voice instructions to drivers, etc.), assuming a human driver capable of taking over in such situations is not present.
Remote control capabilities for authorities are also likely to be mandated at some point due to LEO concerns (already being widely discussed) of unoccupied vehicles (the "vehicle on demand" scenario) being used in criminal or terrorist plots.
Most of these issues have already been covered quite convincingly by prescient science fiction for many decades.
Autonomous vehicle proponents would do well to consider how they're going to respond to government demands along these lines. 'Cause you can be sure that there are teams already in governments around the world brainstorming about their side of this equation.