Even planes, which are almost completely computer controlled have conditions when the pilot muct take over, and the same will be true for cars.  In their essence a computer is nothing more than a fast database and if a particular situation isn't present in the database then the computer won't know what to do.  There are situation that even the experts can't agree on what to do, so how can a computer be expected to decide life and death matters?  We won't see completely self driving cars for a very long time - driver assisted cars sure.