• In the case of Knightley v Johns [1982] 1 W.L.R. 349, it was held that when a whole sequence of events is a natural and probable consequence of a tortfeasor’s negligence and therefore reasonably foreseeable, none of the events in the sequence can be regarded as breaking the chain of causation. Negligent conduct is more likely to break the chain than non-negligent conduct, and positive acts more likely than inaction.

Facts of the Case

  • A motorist drove his car down a tunnel, and at a sharp bend the car somersaulted and came to rest overturned with the motorist inside it, blocking the right-hand lane.
  • C, a police constable, rode out the northern end of the tunnel and radioed for ambulances and a fire engine.
  • C went back into the tunnel to meet with other policemen on the scene. The inspector, D, had forgotten to seal off the tunnel at the other end and told another policeman and C to do so.
  • C followed this other policeman headed down the tunnel the wrong way. An oncoming car swerved to avoid the first policeman, colliding with C.


  • Did D’s order to C to go down the tunnel the wrong way constitute an intervening act that would break the chain of causation stemming from the motorist’s negligence? 

Held by the Court of Appeal (Civil Division)

  • Finding for C, that as the order from a senior policeman to go through the tunnel the wrong way was a negligent act that broke the chain of causation stemming from the motorist’s reckless driving.

Stephenson L.J.

  • The police force Standing Orders alert police officers the dangers of an accident and emergency in a tunnel for cases such as this. They should have been complied with and doing so would have avoided C would not have been injured. C disobeyed them because C was ordered to do so by D. I am not satisfied that C would have disobeyed them, in spite of the implications of his own evidence, unless ordered to do so.
  • “I conclude from these rescue cases that the original tortfeasor, whose negligence created the danger which invites rescuers, will be responsible for injury and damage which are the natural and probable results of the wrongful act, and that those results include injury and damage from accidents of a kind or class which might normally be foreseen or contemplated, though the particular accidents could not be expected. There is no difference between what is natural and probable and what is reasonably foreseeable either in the act of rescue or in the steps taken to accomplish it. If it is natural and probable that someone will come to the rescue it is also foreseeable; if it is foreseeable that in doing so he may take a particular kind of risk or cope with the emergency in ways not precisely foreseeable, his acts will be natural and probable consequences of the wrongful act which created the emergency” [360H].
  • Mistakes and mischances are to be expected when human beings however well trained, have to cope with a crisis; what exactly they will be cannot be predicted, but if those which occur are natural the wrongdoer cannot, escape responsibility for them and their consequences by calling them improbable or unforeseeable.
  • However, it is not reasonably foreseeable that so many errors departing from common sense and procedure would occur in this case. D’s order was not a concurrent cause running with C’s negligence, but a new cause disturbing the sequence of events naturally stemming from C’s negligent driving.