Halachic sources address the situation of two people walking through a public domain, while the one in front is carrying a beam and the one behind carries a barrel. If the person in front suddenly stops, and the person behind him collides with him, breaking his barrel, the person in front bears liability. A person does not have the right to stop suddenly in the public domain without warning the pedestrians behind him. In the case described, the person carrying the barrel acted in a normal, accepted manner, by walking as usual, whereas the person carrying the beam acted in an unusual manner by making a sudden stop. Therefore, the pedestrian that suddenly stopped is responsible for the accident, and bears liability for the damaged barrel.
How would this Halacha affect the case of a car that makes a sudden stop, and the car driving behind crashes into it?
In this case, the driver of the second car, who drove behind the car that stopped short, would bear liability for the damages caused by the crash. All cars today are equipped with brake lights, which turn on whenever a car brakes, alerting the car behind it that it is coming to a stop. Therefore, anytime a car stops in the road, the driver automatically sends a warning to the driver behind him, and it is the rear drivers responsibility to be alert and stop his car in time. Hence, if a car stops short and, as a result, it is hit by the car behind it, the rear driver bears liability for the damages.
Summary: If a car stops short, and, as a result, is hit by the car driving behind it, the rear driver bears liability for the damages, because he should have stopped his car immediately upon seeing the brake lights of the front car.
