The Multiple Meanings of Causation in the Supreme Court of Canada's Medical Malpractice Jurisprudence: Past, Present, and Future
| Author | Joan M. Gilmour |
| Pages | 111-144 |
111
The Multiple Meanings of Causation in
the Supreme Court of Canada’s Medical
Malpractice Jurisprudence: Past, Present,
and Future
joan m. gilmour*
A. INTRODUCTION
Determinations about causation both allocate and limit legal responsibility for
the outcomes of conduct. ey do so, however, in a circumscribed eld—the
inquiry is not to nd all the causes t hat contributed to the harm suered by the
plainti, but to decide whether the acts or omissions of the defendant caused
that harm. e starting point when determining causation in neg ligence claims
has long been the familiar “ but-for” test: the plainti must show on a balance of
probabilities that the injury would not have occurred but for the negligence of
the defendant. It encapsulates the traditional view of who should bear respon-
sibility for injury and why. e underlying rationale is that if the defendant had
taken proper care, the plainti would not have been injured; consequently, it is
considered just to hold the defendant responsible to repair the harm, insofar as
an award of nancial compensation can do so. Once the plainti has satised
the burden of proof, the causal connection is taken as certain, and the plainti
is entitled to full recovery for the injuries suered.
In many cases, what caused the harm is clear, and application of the test
is straightforward. Cause is not contested, or if it is, the but-for test suces to
resolve the issue. Matters cannot always be so easily resolved, however, and cases
about causation raise some of the greatest challenges for courts. Commentators
* e author is grateful f or the research assistance of Ga brielle Cohen.
Hotson v. East Berkshire Health Au thority, [] A.C. per Lord Ackner; Jane
Stapleton, “Cause-In-Fact and the S cope of Liability for Consequences ,” () Law
Q. Rev. , [“Cause-In-Fact”].
112 Health Law at the Supreme Court of Canada
are divided on many of these issues. Courts have moved away from the but-for
test in a numb er of instances, a nd are being pushed to do so in more. It is those
developments on which I will concentrate, examining the present state of the
law, reviewing conicting interpretations, and assessing alternative approaches
to causation that have been proposed or adopted.
Medical malpractice cases are not separate and distinct from personal injury
law generally. However, because they present some of the most dicult analytical
and practical problems, they highlight tensions in the law on causation in stark
terms, and can usefully be analyzed separately. ey are also notable for the ex-
pressions of judicial dissatisfaction and frustration with the existing legal frame-
work that they have triggered; while infrequent, these expressions are nonetheless
powerful. is chapter critically reviews Supreme Court of Canada jurispru-
dence on causation in claims for injury allegedly caused by substandard treat-
ment, as well as failure to warn of risks and/or obtain informed consent. It assesses
ways in which the law of causation has been altered recently by courts in England
and Australia, with a v iew to evaluating the factors relied on to justify departures
from the focus on individual responsibility and individual harm characteristic of
the but-for test. Finally, it consider s the implications of these developments for
Canadian courts in their del iberations on the factual and legal cau ses of harm.
Writing extra-judicially in the late s about the renewed focus on causa-
tion in judicial decisions, McLachlin, J. (as she then was) suggested that “[i]t is this
imbalance between the perception of a wrong and the inability to bring the wrong-
doer to account and compensate the victim that lies, I believe, behind the recent
forays of the courts into the waters of causation that had so long lain tranquil.”
Although Stapleton, ibid. at , notes that in the U.S., the isolated exceptiona l rule of
proof of causation is accepted on ly in medical negl igence claims.
See, for example, Greg g v. Scott, [] UKHL at para. , [] W.L.R. (H. L.), a’g.
[] EWCA Civ. (C.A.), Lord Nichols, di ssenting: if the law were to leave a plai nti
without a remedy when his prospect s of recovery, worsened by the defendant physician’s negl i-
gence, were never better th an percent, then “it would dese rve to be likened to the proverbia l
ass.” See also Rothwell v. Raes (), O.R. (d) at (H.C.J.), Osler J.: “I cannot leave
this tragic a nd extremely dicult c ase without expressing t he view, perhaps unbecoming to
a trial judge, t hat the normal process of litig ation is an utterly inappropriate procedu re for
dealing with c laims of the nature” (unsuccessfu l claim agai nst a physician, vaccine manufa c-
turer and government for injur ies allegedly re sulting from vaccination of i nfant); Ferguson v.
Hamilton Civic Hos pitals (), O.R. (d) (H.C.J.), Krever J. (plainti unable to
establish that if prop erly informed of risks, he would not have proc eeded with operation).
Beverly McLachl in, “Negligence Law — Proving the Connection” in Nichola s Mullaney
& Allen Linden, e ds., Torts Tomorrow: A Tribute to John Fleming (Sydne y, LBC Infor ma-
tion Services, ) at .
Multiple Mean ings of Causation in the S upreme Court’s Medic al Malpractice Ju risprudence 113
Her observation not only acknowledges the existence of popular dissatisfaction
with the fairness or perceived fairness of judicial decisions, but also evidences
some disquiet about the distributive consequences of current understandings
of legal responsibility and liability that underlie these decisions. She goes on to
question whether legal analysis as presently structured may be impeding justied
recovery. is in tu rn raises a number of practical and theoretical issues: Should
the but-for test continue to dominate decision-making about causation and legal
responsibil ity, when are depar tures from it appropri ate, and most i mportantly, on
what basis? More broadly, this query highlights tensions between the role of law
in meetin g social purp oses and a more sel f-contained, form alist unders tanding of
law. As this chapter wil l demonstrate, t he Supreme Court’s deci sions on causation
since , as well as recent developments in the law elsewhere in the Common-
wealth, h ave done more to raise suc h questions than to answer them. It focuses on
dicu lties in proving c ausation in thre e major areas: rs t, when it is clai med that
treatment or care was decient; second, claims of lack of informed consent and
failure to warn of risks; and third, cla ims for loss of chance.
B. CLAIMS OF DEFICIENCIES IN TREATMENT OR CARE
uestions about the cause of harm are oen particularly dicult to ans wer in
the context of health care. Treatment, diagnosis, drugs, devices, and medical
tests —all are ripe for disagreement about their eects, whether these are the
result of wrongdoing on the part of a defendant or would have occurred in any
event, and the extent of defendants’ legal responsibility for outcomes. e real-
ity of patients who are ill or injured and face uncertain prognoses is further
complicated by the disjunction between scientic and legal concepts of evi-
dence and proof, and by limitations on scientic and medical knowledge, such
that in some instances, experts cannot explain what occu rred or why. It can be
dicult or impossible for plaintis to meet the traditional but-for test in these
circumstances. Courts have responded to this reality in a number of ways.
e leadin g Supreme Court of Canada decisions in recent years on causa-
tion in the context of liability for treatment or care are rst, Snell v. Farrell, and
Specically, who should bear t he risks, burdens, and benets t hat tort law assigns, and
on what basis. See general ly Peter Cane, “Distributive Justice and Tort Law” ()
N.Z.L .R. at –, argu ing the centrality of distr ibutive concerns such as this to
concepts of legal resp onsibility and liabi lity.
McLachlin,
supra note .
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