What is the ruling on accidentally hitting a man with a car, leading to his death, due to another car hitting my car from behind?

If your car was hit forcefully and you could not control it, then nothing resulting from the accident is obligatory upon you, because the error did not come from you but from the other party. He is responsible for what happened due to his causing it. Nevertheless, one must refer to the Sharia courts to investigate the matter and issue a just ruling based on all the facts of the accident.