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LAW OF NEGLIGENCE: Intervening Cause (Defendant’s claim)

LAW OF NEGLIGENCE: Intervening Cause (Defendant’s claim)

 The defendant’s
breach of duty may be a cause of the claimant’s damage in the sense that it
satisfies the ‘but for’ test, but some other factual cause, intervening after
the breach, may be regarded as the sole cause of some, or all, of the
claimant’s damage. Where this happens the intervening cause is known as a novus
actus interveniens and breaks the chain of causation between the defendant and
claimant. Any damage occurring after the novus actus interveniens will be regarded
as being too remote.

A negligently runs over B, who is then run over by
C. C’s action is unlikely to break the chain of causation, as this is a risk to
which A’s negligence exposed B. But if C stole B’s wallet, the court would be
unlikely to find A liable, as this was not a risk to which A had exposed B. The
law in this area is far from clear. One of the difficulties is created by the
courts obscuring policy factors with legalistic reasoning. The problem is not
unique to this area, but is particularly acute here. The key policy factor is
the court’s determination of where the loss should lie. The legal (formalistic)
tests used can be demonstrated by two cases.
Office v Dorset Yacht Co Ltd [1970] 2 All ER 294 
Due to the negligence of the defendant’s employees,
borstal trainees escaped and caused damage to neighbouring property. The
majority of the House of Lords treated the case as being concerned with duty of
care. Lord Reid considered that the case was one of remoteness of damage. He
considered whether the boys’ acts broke the chain of causation. In order to do
this they had to be something very unlikely to happen or they would not be
regarded as a novus actus interveniens. As it was very likely that if the boys
escaped, nearby property would be damaged, the boys’ acts did not break the
chain of causation. The escape took place in Dorset and the damage occurred
nearby. Had the boys boarded a train to Carlisle and caused damage there, this
might have been regarded as too remote. 
 The cases show
that, where human action forms one of the links between the original wrongdoing
of the defendant and the loss suffered by the plaintiff, the action must at
least have been something very likely to happen if it is not to be regarded as
a novus actus interveniens breaking the chain of causation. I do not think that
a mere foreseeable possibility is or should be sufficient, for then the
intervening human action can more properly be regarded as a new cause than as a
consequence of the original wrongdoing. But if the intervening action was
likely to happen I do not think that it can matter whether that action was
innocent, tortious or criminal. Lamb v Camden Borough Council [1981] QB 625 The
defendants negligently broke a water main. The water damaged the plaintiff’s
house and caused it to be left empty. Squatters broke in and caused damage. The
question was whether the defendants were liable for the damage caused by the
squatters or whether the squatters’ actions amounted to a novus actus
interveniens. Lord Oliver took up and modified Lord Reid’s test. If the act
should have been foreseen by a reasonable man as likely, it would not break the
chain of causation. He found that the squatters’ actions were not foreseeable in
this sense and therefore did amount to a novus actus interveniens. 
Oliver LJ:
Few things are less certainly predictable than human
behaviour, and if one is asked whether in any given situation a human being may
behave idiotically, irrationally or even criminally the answer must always be
that that is a possibility, for every society has its proportion of idiots and
criminals. It cannot be said that you cannot foresee the possibility that
people will do stupid or criminal acts, because people are constantly doing
stupid or criminal acts. But the question is not what is foreseeable merely as
a possibility but what would the reasonable man actually foresee if he thought
about it . . . If the instant case is approached as a case of negligence and
one asks the question, did the defendants owe a duty not to break a water pipe
so as to cause the plaintiff’s house to be invaded by squatters a year later,
the tenuousness of the linkage between act and result becomes apparent. I
confess that I find it inconceivable that the reasonable man, wielding his pick
in the road in 1973, could be said reasonably to foresee that his puncturing of
a water main would fill the plaintiff’s house with uninvited guests in 1974.
Lord Denning decided the case on the basis of policy. He thought that as the
plaintiff was more likely to be insured against the risk, then the loss should
lie with the plaintiff. This illustrates one of the problems of judges making
policy decisions. In fact, the defendants were more likely to be insured on an all
risks policy for council employees. As the plaintiff had ceased to occupy the
house, it was likely that she was not covered by insurance.
A novus actus interveniens may take one of three forms.
natural event
 The courts will
generally be reluctant to find that a natural event breaks the chain of
causation as the claimant has no one else to sue if the defendant is
exonerated. If the defendant negligently starts a fire and strong winds then
cause the flames to spread to the claimant’s property, the court will not find
that the winds break the chain of causation. However, if the natural event
causes damage simply because the breach of duty has placed the claimant or
their property in a position where the damage can be caused, the chain of
causation will be broken, unless the natural event was likely to happen.
The claimant is injured in a road accident caused by the
defendant’s negligence. An ambulance is called to take the claimant to
hospital. On the way, a strong wind gets up and blows a tree down. The tree
lands on the ambulance and causes further injuries to the claimant. The
defendant will not be liable for the injuries caused by the tree. This will be
treated as a novus actus interveniens which breaks the chain of causation. What
would the position be if there was an exceptionally strong gale blowing at the
time of the original road accident? Should the defendant have foreseen damage
caused by a falling tree?
This principle is illustrated in relation to property
damage by the following case.
Steamship Co v Royal Norwegian Government [1952] AC 292
 The plaintiff’s
ship was damaged in a collision for which the defendant’s ship was responsible.
After temporary repairs the ship set out for the United States on a voyage it
would not have made had the collision not occurred. The ship suffered damage
due to heavy weather conditions. The storm damage was not treated as a
consequence of the collision but as an intervening event in the course of an
ordinary voyage. It is important that the decision of the ship’s owners to put
to sea was voluntary.
act of a third party
Where the defendant’s breach of duty is followed by a
third-party act which is also a cause of the claimant’s damage, the court has
to determine the extent of the defendant’s liability. If the third-party act is
held to be a novus actus interveniens, then the defendant is not liable for any
damage occurring after the act. Where the defendant’s duty was to guard the
claimant or their property from a third party, then the third-party act will
not relieve the defendant from the consequences of their negligence. 
v Troman [1948] 1 All ER 599
The defendant was employed as a decorator by the
plaintiff. He was told to lock the door if he went out. He failed to do this and
a thief (third party) entered the house and stole property belonging to the
plaintiff. The defendant was held liable for the loss, as the thief’s act did
not break the chain of causation. Neither, apparently, will an act of the
claimant.  (Reeves v Commissioner of
Police of the Metropolis [1999] 3 WLR 363.) Recent cases in this area have
tended to concentrate on the aspect of duty rather than remoteness. Where there
is no duty to guard the claimant or their property, the situation is more
difficult. In order to break the chain of causation the third-party act must be
independent of the breach of duty.
Oropesa [1943] P 32
A collision at sea was caused by the negligence of The
Oropesa. The captain of the other ship put out a boat to discuss salvage. At
the time there were very heavy seas. The boat overturned and a sailor was
drowned. The question was whether the captain’s decision to put out the boat
amounted to a novus actus interveniens. The court held that the action of
sending the boat out was caused by and flowed from the collision. As this act
was not independent of the defendants’ negligence it did not break the chain of
causation and the defendants were liable for the sailor’s death.
 “In all these
cases the question is not whether there was what one may call negligence or
not. Negligence involves a breach of duty as between the plaintiff and the
defendant. The captain or Lord, or whoever was deciding what to do, were not
then owing a duty to anybody except, possibly, a duty to minimise damage so far
as they could; but that is not a point which is relevant here. They were acting
in an emergency. If they did something which was outside the exigencies of the
emergency, whether it was from miscalculation or from error, or, if you like,
from mere wilfulness, they would be debarred from saying that there had not
intervened a new cause. The question is not whether there was new negligence,
but whether there was a new cause. It must always be shown that there is
something which I will call ultroneous, something unwarrantable, a new cause
coming in disturbing the sequence of events, something that can be described as
either unreasonable or extraneous or extrinsic.”
 The third-party
act must be voluntary in order to amount to a novus actus interveniens. The
captain’s action in The Oropesa was not voluntary in this sense. Where the
thirdparty act is negligent, it may or may not break the chain of causation.
v Squires [1973] QB 889
The negligence of the first defendant caused an accident.
The second defendant also drove negligently and collided with the vehicles that
had been involved in the first accident, killing the plaintiff. The court held
that the first defendant’s negligence was a cause of the death and he was held
25 per cent responsible. The second accident did not break the chain of
causation as it was a natural consequence of the first accident. 
 If a driver so
negligently manages his vehicle so as to cause it to obstruct the highway and
constitute a danger to other road users, including those who are driving too
fast or not keeping a proper look-out, but not those who deliberately or
recklessly drive into the obstruction, then the first driver’s negligence may
be held to have contributed to the causation of an accident of which the
immediate cause was the negligent driving of the vehicle which because of the
presence of the obstruction collides with it or with some other vehicle or some
other person. Accordingly, I would hold in this case that Mr Allen’s negligence
did contribute to the death of Mr Rouse.
 Knightley v Johns [1982] 1 All ER 851
The negligent driving of the defendant caused an
accident and blocked a road tunnel. A police officer negligently sent the
plaintiff, another police officer, into the tunnel, against the traffic flow.
The defendant was held not liable for the injury to the plaintiff. The court
stated that ‘negligent conduct is more likely to break the chain of causation
than conduct which is not’. Stephenson LJ stated that the courts sought refuge
in ‘common sense rather than logic on the facts and circumstances of each
case’. Negligent medical treatment which intervenes between the breach and the
damage will be treated as novus actus if it is serious and amounts to a
completely inappropriate response to the patient’s condition. (Rahman v
Arearose Ltd [2001] QB 351.) Medical negligence may not sever the chain of
causation and the defendant may remain liable for the damage on the basis that
there was some risk that medical treatment might be negligent.
Where the third-party act consists of deliberate
wrongful conduct, the courts will use the tests set out in Home Office v Dorset
Yacht and Lamb v Camden.
of the claimant
 Cases where the
claimant’s conduct is called into question are normally concerned with
contributory negligence. Where the claimant has been found to have been
contributorily negligent, their damages will be reduced by the proportion that
they are found to be to blame for their damage. However, the defendant may
allege that the claimant’s conduct breaks the chain of causation, so as to
render the defendant not liable for some, or all, of the claimant’s damage. The
test applied by the courts in these cases is whether the claimant was acting
reasonably in the circumstances. 
v Holland & Hannen & Cubbitts (Scotland) Ltd [1969] 3 All ER 1621
 The plaintiff
injured his leg as a result of the defendants’ negligence. Because of his
injury he sometimes lost control of his leg. He attempted to descend a steep
staircase which had no handrail, while holding a small child by the hand. His
leg gave way and he pushed the child to safety. He then jumped to avoid falling
and broke his ankle. The defendants were held not liable for this injury, as
the plaintiff’s unreasonable conduct broke the chain of causation. It was not
the decision to jump that was unreasonable, it was placing himself
unnecessarily in a position where he might be confronted with such an
v Cyril Lord Carpets Ltd [1969] 3 All ER 1006
The plaintiff was unable to adjust her bifocal
spectacles as a result of a neck injury inflicted by the defendant’s
negligence. She was worried about catching public transport in such a condition
and went to her son’s office to ask him to drive her home. On the way into the
office she fell down a flight of stairs and was injured. On these facts the
plaintiff was held to have acted reasonably and the defendant was liable for
her injuries.

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