If your son is at fault in an accident, your husband will be liable because your husband is the registered owner of the vehicle.  Liability will include property damage cost of repairs to the other vehicle not at fault in the accident and the personal injury claims of the occupants of the other vehicle not at fault in the accident.The personal injury claims  will include compensation for medical bills, compensation for pain and suffering which is an amount in addition to the medical bills based on the medical reports and wage loss.If the case is NOT settled with your husband's insurance carrier, your husband will be sued since he is the registered owner of the vehicle your son drives.