Google and other companies have ironed out most of the wrinkles in computer-driven cars, and have even done successful tests on public highways. But policy questions remain, including: how would a police officer pull over an autonomous vehicle?
Here's a question to ponder: would you feel safer in a computer-driven car than you do in one you drive yourself? A self-driving car could succumb to software errors or poor programming -- but on the other hand, it also couldn't fall asleep at the wheel, get lost, or fail to see another vehicle in its blind spot.
The choice between the two is hypothetical for now, but maybe not for much longer.
Autonomous cars aren't on the roads yet, but the technological hurdles have mostly been met by now: Google, BMW, Toyota, and other companies have been working on prototype vehicles for years, and they've even been tested on public roads (in fact, BMW showed off a new self-driving Series 5 vehicle a few days ago). The questions surrounding driverless cars now aren't so much "Are they safe?" and "How do they work?"; rather, they're things like "Would a driverless car need insurance?" and "How would these cars yield right-of-way to each other?"