Knightley v Johns [1981] EWCA Civ 6

A police officer was injured after his senior negligently ordered him to ride against traffic in a one-way tunnel to close it, following an accident. The court found this negligent order was a novus actus interveniens, breaking the chain of causation.

Facts

The first defendant, Mr Johns, negligently overturned his car in a one-way tunnel. The police, including Police Constable Knightley (the plaintiff) and his superior, Inspector Caan, arrived at the scene. Due to the Inspector’s error in managing the scene, the entrance to the tunnel was not closed to oncoming traffic. Realising this, Inspector Caan ordered PC Knightley to ride his police motorcycle against the flow of traffic back through the tunnel to close it. While carrying out this order, PC Knightley was struck and injured by a car driven by the second defendant, Mr Williams, who was not found to be negligent. PC Knightley sued Mr Johns (the original driver) and the Chief Constable of West Midlands Police (vicariously for Inspector Caan).

Issues

The central legal issue was one of causation. The court had to determine whether Inspector Caan’s negligent order to PC Knightley constituted a novus actus interveniens (a new intervening act) that broke the chain of causation starting from Mr Johns’ initial negligent driving. A secondary issue was whether PC Knightley was contributorily negligent in obeying the dangerous order.

Judgment

The Court of Appeal, allowing the appeal, held that the chain of causation had been broken. Stephenson L.J. delivered the leading judgment, providing a detailed analysis of the principles of causation and intervening acts.

Reasoning of the Court

Stephenson L.J. distinguished this case from ‘rescue’ cases where a rescuer’s actions are generally seen as a foreseeable consequence of the initial negligence. Here, the intervention was not merely an instinctive reaction but a specific, negligent order given by a senior officer after the initial emergency had been stabilised. The court held that while some risk to police at an accident scene is foreseeable, a specific act of negligence by an officer in charge was not a foreseeable consequence of the original tortfeasor’s actions.

In his judgment, Stephenson L.J. articulated the key principle for determining when an act breaks the chain of causation:

Negligent conduct is more likely to break the chain of causation than conduct which is not; and the more deliberate, the more consciously free, the more independent of the initial wrongdoing the conduct is, the more likely it is to be treated as a novus actus interveniens.

Applying this principle to the facts, he concluded that Inspector Caan’s order was a new and independent cause of the plaintiff’s injuries:

The inspector’s negligence was a new cause, not a concurrent one. It was a cause which intervened and broke the sequence of events. It was a novus actus interveniens.

The court also held that PC Knightley was not contributorily negligent. He was acting under an express order from a superior officer in an emergency situation, and his decision to obey was not unreasonable in the circumstances. Therefore, the Chief Constable was held vicariously liable for the negligence of Inspector Caan.

Implications

This case is a landmark authority on the doctrine of novus actus interveniens. It clarifies that a third party’s positive act of negligence, particularly when it is a deliberate command from a person in authority, is very likely to break the chain of causation from an initial negligent act. The decision sets a high bar for linking an original tortfeasor to subsequent injuries when there has been a significant and negligent intervention by another party. It underscores the distinction between a foreseeable consequence that is part of an unbroken chain and a new cause which is ‘ultroneous’ or independent, thereby severing the original defendant’s liability.

Verdict: The appeal was allowed. The judgment against the first defendant (Mr Johns) was set aside, and judgment was entered for the plaintiff (PC Knightley) against the third defendant (the Chief Constable) for the agreed sum of damages.

Source: Knightley v Johns [1981] EWCA Civ 6