Where the subsequent event is the act of a third party, the courts have viewed it as breaking the chain of causation if it is unforeseeable. In Knightley v Johns [1982] 1 WLR 349, the first defendant caused a road traffic accident. Subsequently, a police inspector negligently handled traffic control following the accident. This negligence led to the plaintiff, a police officer, being killed (he had been ordered to travel down a tunnel against the flow of oncoming traffic). The first defendant successfully argued that the negligent handling by the police inspector broke the chain of causation between his negligence and the death of the officer.