California is one of the first states to approve rules for the testing of autonomous vehicles on public roads, but driverless cars may already be legal in many states.
The new regulations, which take effect in California on Sept. 16, allow auto manufacturers to test autonomous vehicles (any vehicle that can be operated without a "natural person" physically controlling or monitoring it), provided that they have a certified test driver behind the wheel, receive a testing permit and possess a $5 million insurance or safety bond.
In addition to California, a handful of other states have passed laws regulating automated vehicles. Even so, few laws specifically prohibit their use by manufacturers or the public.