CAUSATION

In order to establish a cause of action in
negligence, a major requirement is that the
plaintiff must show a causal link between
the defendant’s breach of duty and the
injury suffered by the plaintiff. Before we
deal with causation, let us first dispose of
the question of “injury” or “damage” which
the law of negligence would countenance.
Damage Defined

Negligence law does not countenance mere
violation of dignitary interest like one’s
personal reputation or integrity. Rather, the
type of “damage” or “injury” which
negligence law would offer redress is often
a question of policy defined by reference to
whether a “duty of care” obligated the
defendant NOT TO cause the “injury” or
damage in question.
Damage Defined

The concept of “damage” is relative, dependent on
the circumstances of the occasion. Physical
injuries and property damage are apparent and far
less problematic. On the other hand, mental
injuries and economic losses are actionable only
under more restrictive conditions. There are
circumstances where the injury takes a long time
to manifest, in those cases, no right of action will
arise until the injury manifests itself.
Damage Defined
The importance of this principle may be
summarized thus:
 A) It avoids speculative claims,
 B) It sets the time when the statute of
limitation begins to run (this is
advantageous to plaintiffs).

THEORIES OF CAUSATION


As already noted, there is no liability in
negligence unless the dft’s negligent conduct
“caused” the ptf’s “injury”. The question then is
whether “causation” is a matter of fact (objective)
or a policy driven (subjective) criterion?
Fleming and some other scholars posit that the
issue is one of fact. Other scholars have argued
that policy considerations may weigh heavily in
determining “cause in fact”, eg, in injury arising
from a “chain reaction” or by “Murphy’s law”.
Fleming on Causation

Fleming argues that causation is a solely a
question of whether “the dft’s breach of
duty and the ptf’s injury is one of CAUSE
and EFFECT in accordance with objective
notions of PHYSICAL SEQUENCE. If
such a causal relation does not exist, that
puts an end to the ptf’s case.” Fleming, at
218.
Barnett v. Chelsea & K. Hospital

A watchman, after drinking some “tea” which
made him vomit, went to the casualty department
of the defendant’s hospital. His complaints were
recorded by the nurse who in turn passed them on
to a casualty medical officer. The latter asked the
nurse to tell the watchman to go home and consult
his own doctor. Some hours later, the watchman
died from arsenical poisoning. The court absolved
the dft from liability on the ground that the
negligence of the dft did not cause the death.
Causation ad infinitum?

Given that the consequences of a negligent
act may theoretically stretch into infinity,
there must be a limit to the legal
responsibility for the consequences of the
negligent act. It is within this context that
the theory of “causation” as a construction
of policy (subjective) becomes tenable.
Value judgments and legal policy may be
deployed to delimit “causation.”
…For Want of a Nail…
For want of a nail the shoe was lost
 For want of a shoe the horse was lost
 For want of a horse the rider was lost
 For want of a rider the battle was lost
 For want of a battle the kingdom was lost
 And all for the want of a horseshoe nail
Query: Who lost the kingdom? The negligent
blacksmith?

Kaufmann v. T.T.C

While ascending an escalator at the St. Clair
station of TTC, ptf was injured when she fell after
two scuffling youths ahead of her fell back on a
man, who in turn, fell back on her. The SC
reasoned that given that the provision of better
handrails at the station would not have prevented
the accident, there was no causal link between the
ptf’s injury and the lack of better hand rails at the
station.
PROOF OF CAUSAL LINK


The courts have not developed a single test for
satisfying the causal requirement. In theory, every
injury is the culmination of many conditions that
are “jointly sufficient to produce it.” There are
complex contributory factors at work to produce
damage or injury. For example, dropping a lighted
match in a wastepaper basket ignites the basket.
Note that there must be (a) combustible material
(paper) and (b) oxygen to produce the fire.
Query: What “caused” the fire?
The “But for” Test

The first test is whether the alleged factor in the
“causation” chain is NECESSARY to complete
the set of conditions sufficient to produce the
injury in question.This test is universally known as
the “But For” test. If it can be proved, on the
balance of probabilities, that the plaintiff’s injury
would not have occurred WITHOUT (but for) the
defendant’s negligent conduct, the causal
connection IN FACT is established. (Klar, at 321)
…But For…

In other words, applying the “but for” test,
there would be no liability where the injury
or damage would have regardless of the
defendant’s conduct. The primary function
of the test is to weed out from further
consideration factors which would not have
made any difference to the outcome. It is
thus a speculative and evaluative test.
…But For…

The “but for” test requires the court to use
its human experience, best judgment,
intuition, common sense, and sometimes,
expert evidence to speculate on what might
ordinarily have happened “but for” the
defendant’s conduct. However, the decision
is one which need not be made with
mathematical certitude.
The Scope of the “But For” Test

The test is not necessarily CONCLUSIVE.
The factor in question, beyond passing the
“but for” test must scale the additional
hurdle of “proximate” or “legal” cause. The
“but for” test is thus a NECESSARY but
insufficient condition of legal responsibility.
Material Contribution Test

Initially, the courts insisted on a doctrine of strict
proof of causation. While this doctrine was tenable
in cases where a single cause could be attributed to
a harm, in other cases where multiple, independent
“causes” may bring about a single harm, the “but
for” test proved unworkable. In the latter type of
cases, it is virtually impossible to prove causation
with mathematical precision. In attempting to
remedy this defect, the courts devised another test
known as the “material contribution test.”
The Material Contribution Test

Thus, in cases where more than one set of
sufficient conditions can account for a single
injury, the courts ask the question whether each of
the conditions was a substantial factor. For
example, if two persons simultaneously approach
a leaking gas pipe with lighted candles and the
resulting inferno burns down a neighboring house,
it would be unwise to apply the “but for” test as
both tortfeasors may then escape liability. See
Walker Estate v. York Finch Gen. Hospital
The Material Contribution Test


In effect, where there are multiple “causes” each
independently capable of “causing” the single
harm in question, all that the plaintiff is required
to prove is that the dft’s negligence “materially
contributed” to the injury.
Query: if firefighters arrive late and without
equipment, would the owner of a burnt down
house succeed in an action in negligence against
the firefighters?
Materially Increased Risk

Another test, now discredited is “did the dft’s
negligence “materially increase the risk” of injury
to the ptf? This test was formulated McGhee’s
case. The ptf contracted dermatitis from the dft’s
brick yard. The dft’s failure to provide washing
facilities was held to be negligent but it was
unclear whether the provision of washrooms
would have prevented the disease. There was
evidence, however, that the absence of washrooms
materially increased the risk of the ptf contracting
dermatitis.
Retreat from McGhee

The full significance of McGhee is that all
activities which unreasonably increase risk of
injury in society are negligence in law even when
such activities have not in fact caused any injury.
This was a radical, albeit unintended redefinition
of negligence law. Another implication is that
proof by ptf that dft’s conduct “materially
increased the risk” shifts the onus of proving lack
of causation to the defendant. The SC departed
from the logic of McGhee in Snell v. Farrell.
Snell v. Farrell

Ptf became blind in one eye following a cataract
operation by the dft. The trial judge found the dft
negligent because he continued with the operation
after noticing bleeding in the ptf’s eye. Apart from
the dft’s conduct, there were other probable causes
of the ptf’s blindness. Applying McGee, the trial
judge shifted the onus of proving lack of causation
to the dft. On a final appeal to the SC, it was held
that:
Snell v. Farrell



Ordinary causation principles properly applied are
adequate to deal with most cases in negligence.
Principles of proof must not be applied too rigidly
.
Causation is a practical question of fact that can be
answered by ordinary common rather than abstract
metaphysical theory. The courts may therefore use
their general knowledge of life to draw reasonable
inferences of causation.
Impact of Snell on “but for” test

Put simply, in cases where scientific evidence
cannot establish on a balance of probabilities the
connection between dft’s conduct and ptf’s injury,
the ratio in Snell v. Farrell requires the courts to
substitute the “but for” test with reasonable
inference of the cause of the injury. This is a
significant fudging of the rule that a ptf can only
win if s/he proves his/her case on a balance of
probabilities.
Multiple Causes

There are cases where an injury may have been
caused by more than one tortfeasor. In such cases,
proof of causation cannot be done by reliance on
the “but for” test. In Fairchild’s case, the House of
Lords (HOL) had cause to deal with this sort of
problem. Employers had sued 2 employees for
respectively failing to take measures that would
have prevented the employees from inhaling
asbestos. The employees had contracted
mesothelioma.
Multiple Causes

Both employers exposed the employees to the risk
of inhaling asbestos dust but it was unclear and
could not be scientifically which particular
employer had caused the damage. Both employers
had exposed the employers to the same risk of
injury. The HOL was faced with the dilemma of
applying the “but for” test (which would lead to a
dismissal of the suit against the dfts or tweaking
the “but for” test in order to grant relief to the ptfs.
Fairchild v. Glenhaven


If the HOL applied the “but for” test, both
employers would escape liability, as neither would
be the cause of the mesothelioma. Applying the
“material contribution” test, the HOL found for
the ptfs.
Query: What are the concerns with the “material
contribution” test? And what policy reasons
dictate its bias against well heeled defendants?
Athey v. Leonati

The material contribution test cannot be
used to apportion liability between tortious
and non-tortious causes. See Athey v.
Leonati. For it to apply, both possible
causes of the injury but respectively be
tortious.
Cottrelle v. Gerrard

Ptf’s left foot became gangrenous and had to be
amputated below the knee. Trial judge found that
dft doctor was negligent in treating ptf’s diabetes.
However, given the preexisting medical condition
(First Nations Canadian, a smoker and thus at a
higher risk of developing vascular disease and
diabetes which could have developed into a
gangrenous tissue on the foot) ptf and dft expert
witnesses were unsure as to whether ptf’s left leg
would have been saved by the dft. It was held that
the dft was not liable.