Is a bloodwit [diyah] obligatory for someone who hit a young man with his car on a desert highway, leading to his death? And what is its amount, and who pays it, taking into account his family situation and limited income?

If the driver took all necessary safety precautions and measures but could not avoid the accident, then there is no expiation (kaffarah) or blood money (diyah) upon him, because he was not the cause. However, if he was negligent in taking these measures, then he is responsible for the accident, and expiation and blood money are incumbent upon him. The blood money is incumbent upon the 'Aqilah (the male agnates of the offender).