When a car with a driver assist system is the at fault vehicle in a fatal accident, how is it decided whether or not to blame the driver assist system? Is it o

When a car with a driver assist system is the at fault vehicle in a fatal accident, how is it decided whether or not to blame the driver assist system? Is it only blamed if it was in control at the instant the accident occurred? Or does it also get the blame if it was in control shortly before the accident and made poor decisions that set up the accident but then realized it could not handle the situation, disengaged, and told the human to take over?