For the most part the person who caused the rear-ended accident is at fault, regardless of the reason the front driver stopped. Traffic rules require that a driver traveling at a speed at which he or she can stop safely if a vehicle ahead stops suddenly. In rear-ended collisions, the vehicle damage provides strong proof of liability. If the other car’s front end and your car’s rear end are both damaged, there is no doubt that you were struck from behind. You should file a claim against the driver’s insurance.