Knightley v Johns and Others [1982] 1 WLR 349

Law of Tort – Novus Actus Interveniens – Damage – Remoteness of Damage - Causation


Mr Johns was driving negligently and this resulted in a crash where his car overturned near the exit of a tunnel. Due to the crash, two police officers attended the scene. One of the police officer forgot to safely seal off the tunnel to prevent traffic and in response, he ordered the other officer to ride his motorcycle down the one-way tunnel to do so. The officer was against the natural flow of traffic and subsequently; he was involved in a collision.


The case surrounded who was liable for the officer’s injury and whether the instruction of the police officer would be classed as a novus actus interveniens that broke the chain of causation.


The court held that the defendant was negligent and his order was a novus actus interveniens that would negate the car driver’s liability for the police officer’s injuries. While it can be said that the police officers attending the tunnel for the crash was a foreseeable event, the negligent order to drive down a one-way tunnel into opposing traffic was not foreseeable. This third party order broke the chain of causation. This case states that the test for causation is whether the damage is reasonably foreseeable and a ‘natural and probable’ cause of the defendant’s action. In this scenario, the negligent order given by the other police officer could not be reasonably foreseen and therefore, it was a new intervening act that broke the chain of causation.