194 THE ADVOCATE
VOL. 77 PART 2 MARCH 2019
For liability purposes, the court is focused in part on “cause in fact”—that
is, a factual inquiry into what likely caused the plaintiff’s loss.
There is said to be tension here between: (1) the view that defendants
who have been proven at fault should not be allowed to escape liability
because of difficulty in proving a connection between their wrongdoing and
a plaintiff’s loss or injury; and (2) the view that causation is central to the
establishment of liability and that no claimant should be able to recover on
the basis of fault, which is commonplace, without proof that the plaintiff in
fact suffered damage as a result.
The classic “but for” test has repeatedly been reaffirmed as the basis for
finding liability. In Clements v. Clements,14 Chief Justice McLachlin observed
that inherent in the phrase “but for” is the requirement that the defendant’s
negligence was necessary to bring about the injury—in other words, that the
injury would not have occurred without the defendant’s negligence.15
However, several means have been adopted by the Supreme Court of
Canada to mitigate the burden of the onus placed on a plaintiff. These
(1) the “robust and pragmatic approach”, which permits establishment
of “but for” causation by inference without need of “precise” or “scientific”
(2) the rule in Athey under which a defendant found to have made a
“material contribution” to causing injury or loss, sufficient to meet
the “but for” test, may be held fully liable despite not being its sole,
or even main, cause; and
(3) a policy-driven rule under which liability may in certain circumstances
be imposed on a defendant for “materially contributing to
the risk” that harm would be suffered by someone in the plaintiff’s
position—a rare departure from the “but for” rule.
THE “ROBUST AND PRAGMATIC” APPROACH
The “robust and pragmatic approach” introduced in Snell v. Farrell16 and reaffirmed
in Ediger v. Johnston17 and Clements18 permits an inference of causation
to be drawn on the basis of “ordinary common sense” and in the
absence of scientific evidence identifying the cause of the injury.
The expression adopted in Snell is drawn from language used by Lord
Bridge of the House of Lords to emphasize that the law applies a lower standard
than do many medical or scientific experts. The law does not deal in
“certainties”, but rather requires only a “reasonable certainty”—a probability
of, say, fifty-one per cent.