Canada Insurance Lawyer & Attorney : Michael Thomas of Harper Grey Law Firm : British Columbia, Vancouver

Here is a link to the paper that C.E. Hinkson, Q.C. and I wrotet on this topic in December of 2006:

insuranceblog.harpergrey.com/Causation in medical malpractice cases.pdf 

The paper was originally presented to the Trial Lawyers of British Columbia.

Here is the full text of the paper if you prefer to read it here; please note that all formatting has been removed from this exert.  If you want to see the formatted paper please use the link.

CAUSATION IN MEDICAL NEGLIGENCE CASES

A paper written by C.E. Hinkson, Q.C. and M.G. Thomas of Harper Grey LLP
for the Trial Lawyers Association of British Columbia

CAUSATION IN MEDICAL NEGLIGENCE CASES

OVERVIEW

This paper consists of five sections:

The first section provides an overview of the general principles governing causation and to provide an explanation as to how these principles have combined to complicate the law in this area;

The second section describes the "but for" test. Although this section is the shortest, it is arguably the most important, since it is the legal test that is most commonly used to determine causation in medical negligence cases;

The third section discusses the "robust and pragmatic" approach that courts are often encouraged to apply in certain cases when assessing causation. This section attempts to illustrate why the robust and pragmatic approach does not apply to the majority of medical negligence cases;

The fourth section discusses the loss of chance doctrine. Although this section is quite lengthy, it concludes that recovery of damages under the loss of chance doctrine is generally not available to plaintiffs in medical negligence cases involving torts; and

The final section discusses the material contribution test. This section illustrates that the material contribution doctrine is of limited applicability in medical negligence cases.

1. General Principles

Causation is the relationship that must be found to exist between the tortious act of a defendant and the injury to the plaintiff in order to justify compensation of the latter out of the pocket of the former. The plaintiff has the burden of proving, on a balance of probabilities, that the defendant caused or contributed to the injury. Legal theory requires that the plaintiff prove the link between a breach in standard of care, and damages resulting from the breach with certainty. Increasingly, scientific opinions on causal links or relationships are expressed on a continuum of probabilities. This can create a divergence between legal theory and reality. In an attempt to assess causation in cases involving probabilistic causal effects, courts, on occasion, have expanded the "but for" test as an attempt to deal with situations when a causal link is uncertain. However, this expansion has been tempered by judicial deference to the principle that the plaintiff has the burden of proving his or her case on a balance of probabilities. The development of the law of causation cannot be understood without a recognition of these two competing principles.

A review of the English and Canadian medical negligence jurisprudence indicates that the courts have been, and likely will continue to be, reluctant to place liability on a medical professional when causation has not been established by the plaintiff on a balance of probabilities. Therefore, one should be cautious of proceeding with a case where causation cannot be established on a balance of probabilities.

2. The "But For" Test

The general test for causation is the "but for" test which requires the plaintiff to show that the injury would not occur "but for" the negligence of the defendant. The "but for" test will be applied in circumstances where the plaintiff alleges that the defendant’s tortious act was both necessary and sufficient to cause his or her injuries. The "but for" test requires the plaintiff to establish this causal link on a balance of probabilities. The "but for" test is used in the majority of medical negligence cases in assessing whether there is a causal link between an alleged breach in the standard of care owed to a plaintiff and the damages suffered by the plaintiff.

3. A "Robust and Pragmatic" Approach to Causation

There are times when a plaintiff, due to the shortcomings of medical or other scientific expertise, is unable to establish the decisive link between his or her injury and the defendant’s proven breach of duty. The courts have expressed concern that, in such circumstances, a rigid application of the "but for" test and of the burden of proof on a balance of probabilities rewards the careless defendant and denies relief to his probable victim. This problem was recognized by the House of Lords in McGhee v. National Coal Board.

McGhee v. National Coal Board

McGhee v. National Coal Board involved an employee who developed dermatitis from coal dust at his workplace. However, he could not establish that the provision of washing facilities at the workplace would have prevented him from contracting dermatitis. At trial the National Coal Board was found to have breached the standard of care owed to their employees by not providing washing facilities at the workplace. Mr. McGhee worked for several different employers, none of whom provided appropriate washing facilities. The troubling issue was whether any one employer caused Mr. McGhee’s dermatitis. The matter was considered by the House of Lords who determined that Mr. McGhee had established that the failure of each employer to provide washing facilities materially increased the risk of his injury. The decision seemed to imply that once a plaintiff established a material increase in risk, the burden of proof then shifted to the defendant to disprove the causal link. Lord Wilberforce noted:

First, it is a sound principle that where a person has, by breach of a duty of care, created a risk, and an injury occurs within the area of that risk, the loss should be borne by him unless he shows that it had some other cause. Secondly from an evidential point of view, one may ask, why should a man who is able to show that his employer should have taken certain precautions, because then there is a risk, or an added risk, of injury or disease, have to assume the burden of proving more: namely that it was the addition of the risk, caused by the breach of duty, which caused or materially contributed to the injury? In many cases, of which the present is typical, this is impossible to prove, just because honest medical opinion cannot segregate the causes of an illness between compound causes. And if one asks which of the parties, the workman or the employers, should suffer from this inherent evidential difficulty, the answer as a matter of policy or justice should be that it is the creator of the risk who, ex hypothesi must be taken to have foreseen the possibility of damage, who should bear its consequences.

Lord Wilberforce’s comments have been argued by some counsel as reversing the onus of proof on the issue of causation where the plaintiff is able to establish that the defendant’s breach of duty increased the risk of the injury that occurred. However, the subsequent decision of the House of Lords in Wilshire v. Essex Area Health Authority affirmed that this is not the case, and that the plaintiff has the onus of establishing causation on a balance of probabilities remains with the plaintiff.

Wilshire v. Essex Area Health Authority

In Wilshire v. Essex Area Health Authority, a neonate developed an eye condition that was caused either by substandard provision of excessive oxygen to the neonate by employees of the National Health Authority, or occurred due to one of a number of other, non-tortious, factors. The claim against the National Health Authority succeeded in the Court of Appeal based on the causation principles enunciated in McGhee v. National Coal Board. At the Court of Appeal, Sir Nicholas Browne-Wilkinson dissented and distinguished Wilshire v. Essex Area Health Authority from McGhee v. National Coal Board on the basis that in McGhee v. National Coal Board there was only one possible cause of the plaintiff’s dermatitis, whereas in this case there were both tortious and non-tortious potential causes. The House of Lords agreed with Sir Browne-Wilkinson and refused to impose liability on the National Health Authority, which had no control over the other potential causes of the infant’s condition. Wilshire v. Essex Area Health Authority clarified that, notwithstanding McGhee v. National Coal Board, the burden of proof still lay with the plaintiff. Lord Bridge noted:

The conclusion that I draw from these passages is that McGhee v. National Coal Board, [1973] 1 W.L.R. 1 laid down no principle of law whatsoever. On the contrary, it affirmed the principle that the onus of proving causation lies on the pursuer or plaintiff. Adopting a robust and pragmatic approach to the undisputed primary facts of the case, the majority concluded that it was a legitimate inference of fact that the defenders’ negligence had materially contributed to the pursuer’s injury.

Snell v. Farrell

The "robust and pragmatic" approach drawn from McGhee and Wilshire was adopted by the Supreme Court of Canada in Snell v. Farrell. In Snell v. Farrell, the plaintiff underwent a surgical procedure in which the surgeon admitted that his treatment fell below the requisite standard of care. The plaintiff suffered a stroke and went on to develop blindness. Interestingly, neither the plaintiff’s nor the defendant’s experts could say whether the stroke that triggered the plaintiff’s blindness was caused by the admitted negligence, or whether the plaintiff would have gone blind in any event. In understanding the rationale on the finding of causation in Snell v. Farrell it is important to remember that a court is not permitted to abdicate making a finding of fact on causation on the basis that neither the plaintiff nor the defendant could establish or disabuse a causal link on a balance of probabilities. Thus, Snell v. Farrell must be understood as an assessment of causation in circumstances where the court was required to make a legal assessment of causation, despite the fact that expert opinion evidence could not establish or disabuse a causal link on a balance of probabilities.

Sopinka J. provided a number of principles to be considered in assessing causation in these circumstances:

Causation need not be determined with scientific precision;

Factfinders are to take a "robust and pragmatic approach" to the facts that the injured person asserts support the conclusion that the misconduct of a defendant is a factual cause of his or her injury;

Where the relevant facts are particularly within the knowledge of the defendant "very little affirmative evidence will be needed to justify an inference of causation, in the absence of evidence to the contrary; and

Factual causation is a question to be answered by the application of "ordinary common sense".

The classic statement on causation by Sopinka J., often cited in plaintiff’s arguments and facta addressing causation, is as follows:

It is not strictly accurate to speak of the burden shifting to the defendant when what is meant is that evidence adduced by the plaintiff may result in an inference being drawn adverse to the defendant. Whether an inference is or is not drawn is a matter of weighing evidence. The defendant runs the risk of an adverse inference in the absence of evidence to the contrary. This is sometimes referred to as imposing on the defendant a provisional or tactical burden.

The legal or ultimate burden remains with the plaintiff, but in the absence of evidence to the contrary adduced by the defendant, an inference of causation may be drawn although positive or scientific proof of causation has not been adduced. If some evidence to the contrary is adduced by the defendant, the trial judge is entitled to take account of Lord Mansfield’s famous precept. This is, I believe, what Lord Bridge had in mind in Wilshire when he referred to a "robust and pragmatic approach to the … facts".

Snell v. Farrell is a case in which the court, due to evidentiary constraints, had to make a factual finding based on circumstantial evidence. Sopinka J.’s observation that the court may draw an inference of causation when necessary facts lie "particularly within the knowledge of the defendant" strongly suggest an overlap between what was the res ipsa loquiter doctrine and the circumstances in which one may apply the Snell inference of a causal link. Some authors have developed this concept and suggest that the Snell inference is simply an application of the evidentiary rules governing circumstantial evidence.. A close examination of Sopinka J.’s reasons in Snell v. Farrell support this proposition. For example, Sopinka J. notes:

The legal or ultimate burden remains with the plaintiff, but in the absence of evidence to the contrary adduced by the defendant, an inference of causation may be drawn although positive or scientific proof of causation has not been adduced. If some evidence to the contrary is adduced by the defendant, the trial judge is entitled to take account of Lord Mansfield’s famous precept.

Lord Mansfield’s famous precept is that evidence is to be weighed according to the proof which is in the power of one side to have produced and in the power of the other side to have contradicted. It is this maxim that underlies the justification provided by Sopinka J. for allowing probable cause to be inferred, notwithstanding the absence of positive, scientific evidence of probable cause in medical negligence causes. Sopinka J. summarized the circumstances in which the Snell inference could be relied upon in medical negligence cases as follows:

In many malpractice cases, the facts lie particularly within the knowledge of the defendant. In these circumstances, very little affirmative evidence on the part of the plaintiff will justify the drawing of an inference of causation in the absence of evidence to the contrary.

Evidentiary Rules Governing Circumstantial Evidence

Although the res ipsa loquiter doctrine was formally abolished in Canada in Fontaine v. British Columbia, [1998] 1 S.C.R. 424, the doctrine did not disappear; it was simply re-characterized as an evidentiary rule governing the use that could be made of circumstantial evidence. Major J. summarized the evidentiary rule governing circumstantial evidence as follows:

If the plaintiff has no direct or positive evidence which can explain the occurrence and prove that the defendant was negligent, appropriate circumstantial evidence, as defined by the maxim res ipsa loquiter, may be introduced.

…

It would appear that the law would be better served if the maxim [res ipsa loquiter] was treated as expired and no longer used as a separate component action in negligence actions. After all, it was nothing more than an attempt to deal with circumstantial evidence. That evidence is more sensibly dealt with the trier of fact, who should weigh the circumstantial evidence with the direct evidence, if any, to determine whether the plaintiff has established on the balance of probabilities a prima facie case of negligence against the defendant. Once the plaintiff has done so, the defendant must present evidence negating that of the plaintiff or necessarily the plaintiff will succeed.

The rules of evidence governing the use of circumstantial evidence established by Fontaine v. British Columbia define the circumstances in which the Snell inference process may be used. This is reflected by the fact that in circumstances where affirmative evidence has been led by a defendant [on causation], the Snell inference has been found to be inapplicable.

Application of Circumstantial Evidentiary Rule in British Columbia

In Moore v. Castlegar & District Hospital, the plaintiff established that the defendant doctor breached the duty of care owed to the plaintiff by failing to take appropriate spinal x-rays following a motor vehicle accident. At issue was whether the plaintiff’s spinal cord injury occurred in the hospital, or whether the injury occurred at the time of the accident. Both parties led evidence on the issue of causation. The trial judge rejected the plaintiff’s evidence on causation, accepted the defendant’s evidence on causation and dismissed the action. On appeal, the plaintiff contended that the trial judge erred in failing to draw an inference, in the absence of affirmative x-ray evidence, that the defendant’s spinal cord injury occurred after he arrived in the hospital. Hollinrake J.A. determined that, since expert evidence had been led on the causation issue, this was not a circumstance in which the court could rely upon the Snell inference of causation:

With respect, I think in a case such as this where there is affirmative medical evidence leading to a medical conclusion it is not open to apply "the common sense reasoning urged in Snell v. Farrell". I take it this is what the trial judge was referring to when she said:

All parties have led evidence on this issue [causation] and it would be inappropriate to resort to an inferential analysis as was argued on the plaintiff’s behalf.

I share that view.

This principle was reaffirmed by our Court of Appeal in Bigcharles v. Dawson Creek and District Health Care Society. In addition, our Supreme Court has interpreted Moore v. Castlegar & District Hospital as standing for the proposition that the Snell inference approach is limited to situations in which there is no affirmative expert evidence addressing factual causation.

Conclusions on Inferences of Causation

In British Columbia, the circumstances in which a court may draw an inference of causation are more limited in medical negligence cases than Sopinka J.’s initial wording in Snell v. Farrell might lead one to suspect. The first limitation is that the "but for" test must not be appropriate. The second limitation is that there is no affirmative evidence on causation. The final qualification is that the Snell inference is constrained by the current evidentiary law governing inferences that may be drawn from circumstantial evidence.

4. Loss of Chance

When a plaintiff must establish a loss on a balance of probabilities, difficulties arise if the tortious conduct of a defendant deprive the plaintiff of a chance of avoiding an injury of less than 50 percent. The idea that a plaintiff may recover for the "lost opportunity", even if the chance of that opportunity materializing again was less than 50 percent, was first set out in Chaplin v. Hicks, [1911] 2 K.B. 786 (C.A.).

Chaplin v. Hicks

In Chaplin, the plaintiff entered into a beauty contest in which 12 winners would be awarded prizes. The plaintiff was selected as one of the 50 finalists for one of the 12 prizes, but the defendant failed to properly notify her and she lost her chance at the prize. The court concluded that her chances of winning the prize were 12 out of 50, or 24 percent. Despite the fact that the plaintiff could only prove a possible loss, as opposed to a loss on a balance of probabilities, the court held that the defendant had breached his contract by failing to use reasonable efforts to notify the plaintiff. The plaintiff was awarded nominal damages of £100. Chaplin established the principle that, at least in contract cases, damages could be awarded for lost chances, even when the chances were well under the traditional "but for" threshold of 50 percent.

Seyfert v. Burnaby Hospital Society

One example of the application of the loss of chance doctrine is Seyfert v. Burnaby Hospital Society (1986), 27 D.L.R. (4th) 96 (B.C.S.C). In Seyfert v. Burnaby Hospital Society, the plaintiff injured his abdomen. The court found that the treating physician failed to provide him with appropriate treatment and his failure resulted in a delay in obtaining appropriate treatment. The issue at trial was whether the delay in providing the plaintiff with treatment made the plaintiff more susceptible to complications. Relying on McGhee v. National Coal, McEachern C.J.S.C., as he then was, held that the negligence had materially contributed to the risk of complications and awarded 25 percent of the damages representing the loss of chance of avoiding the complications and a longer period of convalescence.

Hotson v. East Berkshire Area Health Authority

McEachern C.J.S.C.’s approach was explicitly rejected in England by the House of Lords in Hotson v. East Berkshire Area Health Authority, [1987] 2 All E.R. 909 (H.L.). In Hotson v. East Berkshire Area Health Authority, a child fell from a tree and received negligent treatment from a doctor. The trial judge found that there was a 75 percent chance that the child’s eventual loss occurred even with appropriate care, and awarded 25 percent of the damages on that basis. The House of Lords analyzed the trial judge’s finding and found that the plaintiff had only established a possible loss. Since the plaintiff had failed to prove "but for" causation on the balance of probabilities, the case was dismissed against the physician.

Laferriere v. Lawson

The applicability of the loss of chance doctrine in a medical negligence setting was considered by the S.C.C. in Laferriere v. Lawson (1991), 78 D.L.R. 4, 609 (S.C.C.). In Laferriere v. Lawson, the defendant physician failed to advise a plaintiff that she had cancer, of which she died in 1978. The issue before the court was whether the plaintiff, who had not been informed of the diagnosis of cancer, should be compensated for the loss of chance of obtaining treatment and possibly avoid her subsequent death. The opinion evidence clearly established that the loss of any benefit of treatment, if it existed at all, was substantially less than 50 percent. The Supreme Court of Canada clearly rejected the notion of compensation for a loss of chance in tort, confining recovery to cases where breach of duty is linked to damages on a balance of probabilities. Gonthier J. rejected the application of the loss of chance doctrine in medical negligence cases:

I do not feel it is appropriate to focus on the degree of probability of success and to compensate accordingly …"

…

[I]t is only in exceptional loss of chance cases that a judge is presented with a situation where the damage can only be understood in probabilistic or statistical terms, and where it is impossible to evaluate sensibly whether or how the chance would have been realised in that particular case. The purest example of such a lost chance is that of the lottery ticket which is not placed in the draw due to the negligence of the seller of the ticket. The judge has no factual context in which to evaluate the likely result other than the realm of pure statistical chance. Effectively, the pool of factual evidence regarding the various eventualities in the particular case is dry in such cases, and the plaintiff has nothing other than statistics to elaborate the claim in damages

…

I am not prepared to conclude that particular medical conditions should be treated for purposes of causation as the equivalent of diffuse elements of pure chance, analogous to the nonspecific factors of fate or fortune which influence the outcome of a lottery.

de la Giroday v. Brough

The issue of loss of chance was considered by our Court of Appeal in de la Giroday v. Brough, [1997] B.C.J. No. 1146 (B.C.C.A.). In de la Giroday v. Brough, the plaintiff suffered from necrotizing fasciitis. The condition was not diagnosed initially by the emergency physician and the plaintiff’s diagnosis and treatment was delayed. The expert evidence accepted by the court was that a possibility existed that the plaintiff would have been diagnosed earlier if he had been referred to a tertiary care facility, but the evidence of this did not rise above a possibility. The majority of the British Columbia Court of Appeal held that the action against the defendant physician sounded in both contract and tort, but that the tort action was barred by the loss of chance doctrine. The majority concluded - in absence of any specific pleading or evidence - that a contract existed between the plaintiff and the defendant and that every breach of contract entitled the innocent party to at least some damages, even if nominal. In the result, the majority found the contractual loss of chance approach could be applied in medical negligence cases. Southin J.A. noted:

For the loss of chance approach to apply in this country in actions of tort would require either a legislative amendment or a decision to that effect of the Supreme Court of Canada. But I see no legal impediment to applying the approach of Dylan L.J. [in Hotson v. East Berkshire Area Health Authority] to an action in contract for breach of the implied obligation to exercise reasonable care and skill.

The result was that the British Columbia Court of Appeal ordered a new trial to decide whether there was a breach of contract and whether and to what extent the plaintiff suffered a loss of chance. It is important to recognize that this decision was rendered in the context of the old Medical Service Act, R.S.B.C. 1979, c. 255 and the Medical Services Plan Act, R.S.B.C. 1981, c. 18. Southin J.A. emphasized that her decision was only binding on actions arising from the old legislation:

I say that only that the relationship between the patient and physician remain contractual. As to whether it does so now under the replacement statute, the Medicare Protection Act, R.S.B.C. 1996, c. 286, first enacted in 1992, c. 76 of that year, I make no comment.

In Oliver (Public Trustee of) v. Ellison 2001 BCCA 359, Southin J.A. appears to adopted the position of the majority of the Court of Appeal in de la Giroday v. Brough. Southin J.A. notes, at paragraph 35:

35. I think there may be here some confusion to which I may have materially contributed. The principal question in de la Giroday v. Brough was whether the appellant had a cause of action for Dr. Brough’s breach of duty. We found that he did on the footing that there was a contract between them and that every breach of contract imports damage (para. 34). In other words, damage is not the gist of an action for breach of contract. For that reason, the court directed a new trial. It may be said with some justice that the discussion of "loss of chance" was obiter. It can also be said that, as counsel for the respondent physician in that case gave no analysis to the court of the Medical Services Plan, it is now open to the present respondents to argue that upon its true construction, it is a scheme of the same order as that which led to the courts in Hotson v. East Berkshire Area Health Authority, infra, proceeding on the footing that the only action which the plaintiff could have sounded in tort. I agree the point is open.

In coming to its decision in de la Giroday v. Brough, our Court of Appeal noted that Laferriere v. Lawson, [1991] 1 S.C.R. 541 was a civil law case which did not, in any way, address the implications at common law of contract for medical services in British Columbia. After de la Giroday v. Brough, the Supreme Court of Canada in Arndt v. Smith, [1999] 2 S.C.R. 539 (S.C.C.) suggested that the principles in Laferriere v. Lawson should be equally applicable in common law jurisdictions. McLachlin J., as she then was, went on to say at paragraph 43:

This approach accords with the decision of this court in Laferriere v. Lawson, [1991] 1 S.C.R. 541 which held (at p. 609) that causation "must be established on the balance of probabilities, taking into account all the evidence: factual, statistical and that which the judge is entitled to presume". It is consistent with the view there expressed that "statistical evidence may be helpful as indicative but is not determinative", and that "where statistical evidence does not indicate causation on the balance of probabilities, causation in law may nonetheless exist where the evidence in the case supports such finding". While Laferriere arose in the context of the civil law effect, Gonthier J., speaking for a majority of the court, made extensive reference to common law jurisdictions, suggesting that the principles discussed may be equally applicable in other provinces.

No Prima Facie Action in Contract in Medical Negligence Cases?

The issue as to whether an action lies in medical negligence in contract or tort was further considered by our Court of Appeal in Letvad v. Fenwick (2000), 2 B.C.L.R (3d) 296. Esson J.A. noted for the court, in the context of an application to amend this Statement of Claim to plead, inter alia, breach of contract in the provision of medical care, the following:

The remaining question arises from the fact that the amended Statement of Claim raised for the first time an allegation of a breach of contract against the hospital. The plea nay raised no fresh factual issues. Primarily, it is an acknowledgement of the view that contract and negligence exist concurrently in circumstances such as are alleged here. See de la Giroday v. Brough (1997), 33 B.C.L.R. (3d) 171 (C.A.). The purpose of raising that plea appears that it might open the way to damages being assessed on the basis on a loss of chance - an approach which is not available in a negligence action. It may be doubted that, as a matter of law, such a claim can succeed.

In Oliver (Public Trustee of) v. Ellison (1998), B.C.J. No. 589 (B.C.S.C), the learned trial judge applied Laferriere v. Lawson to dismiss a claim for loss of chance at para. 25:

At most, the evidence of Ms. Soolsma establishes that by virtue of failing to contact the nursing supervisor, who may have chosen to override Dr. Mitchell, there was the "loss of a chance" that Ms. Oliver’s clinical management may have been altered by Dr. Mitchell. It is clear that an increased possibility of injury as a result of a failure in medical care (otherwise described as a "loss of chance") is not compensable.

This decision was appealed, with the plaintiff arguing that the Court of Appeal ought to entertain a claim in contract. The majority disagreed, given that the claim was not advanced in the court below.

St-Jean v. Mercier

In St-Jean v. Mercier, [2002] 1 R.S.C. 491, a case decided under Quebec civil law, the Supreme Court emphasized that what it said in Laferriere v. Lawson was "worth repeating". In Mercier, the plaintiff sued his orthopedic surgeon for injuries arising out of his treatment following a motor vehicle accident. The lower court found that appropriate medical care, through early immobilization and diminuation of the swelling of the spinal cord, offered "chances of recuperation that were more than simple possibilities". The Supreme Court of Canada noted:

…the Court of Appeal basically found the likelihood of an early immobilization leading to recuperation to be somewhere on the spectrum in between the poles of possibility and probability: greater than the realm of what is merely possible but still not enough to meet the threshold of probability. The initial harm of the accident simply outweighed any kind of effect the faulty treatment might have had, to the point where it cannot be said on a probabilistic basis that the faulty treatment had any causal effect. It is worth repeating the traditional principle set out in Laferriere v. Lawson, [1991] 1 S.C.R. 541, at pp. 608-609, where I found that causation must be established on a balance of probabilities and that the loss of a mere chance cannot be a compensable harm. (at page 38). Accordingly, the chances of recuperation in this case were not significant enough on a balance of probabilities to establish that the faulty treatment caused the harm suffered.

Fraser Park South Estate Limited v. Lang Michener Lawrence & Shaw et al.

The rejection of the loss of chance doctrine in tort, and its limitation to nominal damages in contract was affirmed in a majority decision by our Court of Appeal in Fraser Park South Estate Limited v. Lang Michener Lawrence & Shaw et al (2001), 146 B.C.A.C. 86. In dissent, Southin J.A. would have awarded more than nominal damages based on a breach of contract, but, of significance to causation in alleged medical negligence cases, noted that loss of chance is generally not applicable in tort actions:

45. It is necessary to struggle with "causation" when the claim sounds in tort, for proof that the lack of reasonable care caused damage is of the essence of the tort of negligence. That causal connection must be proven on a balance of probabilities but in contract the cause of action is complete once the breach is established. See the discussion of this point in my judgment in de la Giroday v. Brough (1997), 33 B.C.L.R. (3d) 171 (C.A.), which I shall not repeat here.

Other Noteworthy Decisions

The loss of chance doctrine was rejected in the medical negligence context by the Ontario Court of Appeal in Cottrelle v. Gerrard, [2004] 233 D.L.R. (4th) 45 (Ont. C.A.). In Cottrelle, not only did the Ontario Court of Appeal confirm that recovery on the basis of loss of chance is not available to plaintiffs in medical negligence case, but the court noted that it was bound by the cases of St-Jean v. Mercier and Laferriere v. Lawson.

Similarly, in the United Kingdom, the majority of the House of Lords in the recent case of Gregg v. Scott, [2005] U.K.H.L. at 2 the majority of the House of Lords rejected the introduction of a loss of chance approach. In rejecting the loss of chance doctrine, Lord Hoffman noted that a wholesale adoption of possible rather than probable causation as the criterion of liability would be so radical a change in law as to amount to a legislative act:

89. In Fairchild’s case [2003] 1 AC 32, 68, Lord Nicholls of Birkenhead said of new departures in the law:

To be acceptable the law must be coherent. It must be principled. The basis on which one case, or one type of case, is distinguished from another should be transparent and capable of identification. When a decision departs from principles normally applied, the basis for doing so must be rational and justifiable if the decision is to avoid the reproach that hard cases make bad law.

90. I respectfully agree. And in my opinion, the various control mechanisms proposed to confine liability for loss of a chance within artificial limits do not pass this test. But a wholesale adoption of possible rather than probable causation as the criterion of liability would be so radical a change in our law as to amount to a legislative act. It would have enormous consequences for insurance companies and the National Health Service. In company with my noble and learned friends Lord Phillips of Worth Matravers and Baroness Hale of Richmond, I think that any such change should be left to Parliament.

Gregg v. Scott was recently relied upon by Garson J. in Seatle (Guardian ad litem) v. Purvis [2005] BCSC 1567 to reject a loss of chance argument in an alleged medical negligence action.

Conclusions on Loss of Chance

Loss of chance in a medical negligence action is limited to situations when the plaintiff can establish a contractual relationship between himself or herself and the physician, and may result in restricting damages to a nominal amount. If plaintiffs wish to advance a loss of chance case, breach of contract should be specifically pled and proven at trial.

5. Material Contribution

Athey v. Leonati, [1996] 3 S.C.R. 458 represents the Supreme Court of Canada’s next significant departure after Snell v. Farrell from the "but for" test. In Athey v. Leonati, the court ruled that in some circumstances it is sufficient to prove that it is more likely than not that a defendant "materially contributed" to an injury in order to satisfy a causal link to damages.

Athey v. Leonati

In Athey v. Leonati, the plaintiff had a history of back problems. He was involved in two successive motor vehicle accidents. The defendants in each accident admitted liability. Following the second motor vehicle accident, the plaintiff suffered a disc herniation while stretching in a health club. The plaintiff sued the two defendants who had caused the prior accidents. At trial, the only issue was whether the disc herniation was caused by the injuries sustained in the accidents, or whether they were attributable to the plaintiff’s pre-existing back condition. The trial judge held that, although the accidents were not "the sole cause" of the disc herniation, they played "some causative role", which was assessed at 25 percent. The trial judge then awarded the plaintiff 25 percent of the damages to represent the reduced role of the accidents.

The Supreme Court of Canada held that the defendants were liable for all of the plaintiff’s damages on the basis that their negligence was proven to have caused or materially contributed to the plaintiff’s injuries. The Supreme Court of Canada noted that a contributing factor was material if it falls outside the de minimis range. Once it is established that the defendant’s breach is a "materially contributing cause" of the plaintiff’s injury, the defendant will be fully liable for the plaintiff’s damages caused by his fault. The defendant is not excused from liability merely because other causal factors, for which he or she is not responsible, helped to produce the plaintiff’s damages. The issue as to when one may use the material contribution test to replace the "but for" test is controversial. Athey v. Leonati itself provides little guidance with respect to when the material contribution test can be applied, however, it is clear that, no matter whether the "but for" test or the material contribution test is used, the plaintiff has the burden of establishing causation on a balance of probabilities. This was recently affirmed by the Supreme Court of Canada in Blackwater v. Plint 2005 SCC 58 at paragraph 78.

Walker Estate v. York Finch General Hospital

The difficulty in determining when the material contribution test should be applied is illustrated by the Supreme Court of Canada decision in Walker Estate v. York Finch General Hospital, [2001] 1 S.C.R. 647. In Walker Estate v. York Finch General Hospital, three plaintiffs contracted AIDS from blood and blood products supplied by the Canadian Red Cross Society before the ability to test for HIV in blood existed. The Red Cross screen procedures included a questionnaire which was given to potential donors. The questionnaire did not ask symptom-specific questions about HIV. Thus, the donors, after filling out the questionnaire, would not have identified themselves as people who might have HIV. The court determined that the Red Cross Society was negligent in not asking symptom-specific questions about HIV in their questionnaires.

The causation question ultimately turned on whether the infected donor would or would not have donated the tainted blood if he had been provided the appropriate questionnaire. The court decided to approach the question of causation by applying the "material contribution" test. According to the court, the Red Cross’ negligence in failing to screen donors who were at risk of having HIV was a material contribution, falling outside the de minimis range to the occurrence of the plaintiff’s injury. At paragraph 88, the court noted:

In cases of negligent donor screen, it may be difficult or impossible to prove hypothetically what the doctor would have done had he or she been properly screened by the CRCS (the Red Cross). The added element of donor conduct in these cases means that the but for test could operate unfairly, highlighting the possibility of leaving legitimate plaintiffs uncompensated. Thus, a question in cases of negligent donor screen should not be whether the CRCS’ conduct was a necessary condition for the plaintiff’s injuries using the "but for" test but whether the conduct was a sufficient condition. The proper test for causation in cases of negligent donor screen is where the defendant’s negligence "materially contributed" to the occurrence of the injury. In the present case, it is clear that it did. "A contributing factor is material if it falls outside the de minimis range." (See Athey v. Leonati, [1996] 3 S.C.R. 458 at para. 15). As such the plaintiff retains the burden of proving that the failure of the CRCS to screen donors with tainted blood materially contributed to Walker contracting HIV from tainted blood.

After Walker Estate v. York Finch General Hospital it is difficult to understand when the material contribution test may be used to establish causation. Until Walker Estate v. York Finch General Hospital, it appeared that the use of the material contribution test was limited to cases of cumulative causation. Application of the "but for" test would have nullified the plaintiff’s claim in Walker Estate -- the plaintiff’s contraction of AIDS would only be actionable if the contraction of the disease was caused by a donation that would have been avoided by a proper screening. The Supreme Court of Canada noted that it was not possible to present any evidence on that central issue. Therefore, the court applied the material contribution test in order to establish causation. Paragraph 88 of Walker Estate v. York Finch General Hospital appears to suggest that the expansion of the "but for" test is limited to cases involving negligent donor screening. Alternatively, one could argue that the negligence of the Red Cross caused an increase in risk of the type of harm that developed and that the causal link was based upon an increase in the risk of harm. This interpretation is compelling because it is consistent with the subsequent House of Lord decisions of Fairchild and Gregg.

St-Jean v. Mercier

The central issue raised by Walker Estate v. York Finch General Hospital, in the medical negligence context, is whether the circumstances in which the material contribution test could be applied will be expanded to enable plaintiffs to recover for damages causally linked to conduct on less than a balance of probabilities. The Supreme Court of Canada clarified that, regardless of Walker Estate v. York Finch General Hospital, once must still prove causation in medical negligence cases on a balance of probabilities.

In St-Jean v. Mercier (2002), S.C.C. 15, the plaintiff was hit by an automobile and transported by ambulance to a hospital. He had open fractures in both legs and was bleeding from the head. He underwent emergent surgery for his legs, and a subsequent surgery thereafter. After discharge, it was determined that he had suffered a fracture at the T7 level and went on to develop paraparesis in his legs. The defendant physician did not fully investigate or treat the injury to the plaintiff’s spine. The trial judge determined that the care provided by the defendant physician was appropriate and that the lack of treatment of the spinal fracture was not causally linked to the plaintiff’s paraparesis. The Court of Appeal reviewed the findings of the trial judge and determined that the defendant physician breached the standard of care in not making further inquiries into the plaintiff’s spinal fracture. However, the Court of Appeal concluded that, notwithstanding the faults committed by the physician, the accident was the legal cause of the plaintiff’s paraparesis and that there was no causal link between the delayed diagnosis and the plaintiff’s injuries.

At the Supreme Court of Canada, the plaintiff strenuously argued that the circumstances required that the court draw an inference of causation against the defendant physician. The plaintiff noted that the defendant physician created a risk and that the harm subsequently occurred within the ambit of the risk created such that there should be an inference of causation. In addition, the plaintiff argued that the defendant’s negligence deprived the plaintiff of some important means of proof and therefore there should be a reversal of the burden of proof onto the defendant to show that his fault did not cause the damage. The Supreme Court of Canada rejected both of these arguments, noting:

The Court of Appeal appropriately said that it was insufficient to show that the defendant created a risk of harm and that the harm subsequently occurred within the ambit of the risk created. To the extent that such a notion is a separate means of proof with a less stringent standard to satisfy, Snell, supra, and definitely Laferriere, supra, should have put an end to such attempts at circumventing the traditional rules of proof and the balance of probabilities. There may be a misapprehension of what I said in Laferriere, supra, at page 609:

In some cases, where a fault presents a clear danger and where such a danger materializes, it may be reasonable to presume a causal link, unless there is a demonstration or indication to the contrary.

This is merely a reiteration of the traditional approach on presumptions and does not create another means of proof in Quebec civil law in the establishment of the causal link. The Court of Appeal correctly interpreted this passage as pertaining to presumptions within the traditional rules of causation.

St-Jean v. Mercier is important because it indicates that the circumstances when the material contribution test are expanded are limited in the medical negligence context. Applying the material contribution test to situations involving multiple causative effects is synonymous with allowing recovery for loss of chance. The Supreme Court of Canada affirmed that causation must be proven using the "but for" test on a balance of probabilities and one cannot adapt the material contribution test to circumvent this requirement.

Cottrelle v. Gerrard

Cottrelle v. Gerrard is a leading case on causation in the medical negligence context. Ms. Cottrelle was a diabetic who was at a high risk for the development of a vascular disease, a risk which was further increased by the fact that she was Aboriginal and a smoker. She developed a sore between her toes and saw her physician, who prescribed a topical cream. No arrangements for a follow-up visit were made, and the physician did not re-examine the plaintiff’s foot until she subsequently visited him five weeks later. Five weeks after that visit, she attended at an emergency department of a hospital where the emergency physician prescribed oral antibiotics. She arranged to see her physician a few days after her emergency department visit. The physician did not examine her foot and referred her to a skin specialist, which was scheduled approximately two months later. Three months after that visit to her physician, the plaintiff’s foot developed gangrene and required amputation.

The plaintiff’s theory of causation was that her physician should have admitted her to hospital for more aggressive treatment and that, had he done so, the infection could have been controlled through antibiotics or the amputation of a toe as opposed to the plaintiff’s leg. The physician’s theory of causation was that, given the serious nature of the infection, more aggressive treatment would not have made any difference. The trial judge determined that the defendant’s failure to provide more aggressive treatment to the plaintiff caused her injuries. The trial judge based her analysis of the causation on the basis that the physician’s lack of action materially contributed to the development of a deeper infection, which materially contributed to the development of gangrene and the resulting need for a below-the-knee amputation.

At the Ontario Court of Appeal plaintiff’s counsel conceded that there was no evidence suggesting that it was more likely than not that had the defendant lived up to the standard of care, the plaintiff’s leg would have been saved. Plaintiff’s counsel argued that the evidence of a possibility, lower than a probability, that the respondent’s leg might have been saved satisfied the material contribution test in Athey v. Leonati. The Court of Appeal rejected this submission:

The "but for" test has been relaxed as "unworkable" in cases where, practically speaking, it is impossible to determine the precise cause of the injury. In Athey, for example, the Supreme Court affirmed the "material contribution" test as a qualification to the strict "but for" test only when used in cases similar to Bonnington Castings Ltd. v. Wardlaw, [1956] 1 All E.R. 615 (H.L.), and McGhee v. National Coal Board, [1972] 3 All E.R. 1008 (H.L.). The more recent House of Lords decision in Fairchild v. Glenhaven Funeral Services Ltd., [2002] 3 All E.R. 305 (H.L.), also reflects this same tendency to depart from the "but for" standard, but only where the precise cause of the injury is unknown. Bonnington, McGhee, and Fairchild all involved situations where the plaintiff was exposed to a harmful substance from various sources, but could not prove precisely that the substance resulting from the defendant’s tortious conduct caused the loss. In Fairchild, the plaintiffs had been exposed to asbestos while working for various employers for various periods. The plaintiffs developed a fatal disease caused by asbestos, but could not establish which exposure or exposures to asbestos had actually caused the disease. The House of Lords allowed the plaintiffs’ appeals form lower court decisions dismissing their claims and held that they were entitled to recover. The salient feature of Fairchild was that the plaintiffs were definitely injured by the negligence of one of the defendants, and there was no other operative cause or explanation for the injury. As pointed out in Lewis N. Klar, Tort Law, 3rd ed. (Toronto: Thomson, 2003) at 400: "courts will strive to fashion a just solution in this type of case to allow a wronged plaintiff to recover. Courts will not allow wronged plaintiffs to fall between the cracks due to the formal requirements of proving cause."

In my view, the principle followed in this line of cases does not assist the respondent. In the case at bar, there is no practical uncertainty as to the impact of the appellant’s wrongful conduct upon the plight of the respondent. It was clearly established that the respondent lost her leg because of an infection. The question was whether the appellant could have prevented an outcome that was unquestionably caused by the infection and the respondent’s pre-existing vascular condition. The evidence demonstrated that it is more likely than not that even if the appellant had lived up to the standard of care, the respondent would have lost her leg.

Nor, in my view, is the respondent assisted by the principle established in Snell v. Farrell, [1990] 2 S.C.R. 311, 72 D.L.R. (4th) 289. Snell involved a situation in which the plaintiff became blind following cataract surgery. The court found the defendant negligent in proceeding with the operation despite retrobulbar bleeding. The expert witnesses who testified were unable to say with certainty what caused the plaintiff’s blindness, but the retrobulbar bleeding was found to be a possible cause. In Snell, Sopinka J. held that the plaintiff did not need to prove with scientific precision that the bleeding was the cause of her blindness, particularly since the facts as to precisely what had occurred during the surgery were within the knowledge of the defendant.

The "robust and pragmatic" approach to proof of causation utilized in Snell v. Farrell does not assist the respondent. In the case at bar, there is no uncertainty over why Darlene Cottrelle suffered the amputation of her leg and this is not a case where the appellant is in a better position to say what happened. Here, the issue is not whether the appellant created a situation that might have caused the respondent’s loss. Instead, the issue is whether the appellant could have prevented the loss of the respondent’s leg in any event. In this case, the experts agree that it is more likely than not that even if the appellant had met the appropriate standard of care, the respondent still would have lost her leg.

In addition, Cottrelle makes it clear that the majority of delayed diagnosis cases should be analyzed using the doctrine of loss of chance, as opposed to using the Athey material contribution analysis, and are generally not recoverable. Sharpe J.A. notes:

I agree with the appellant’s submission that the case at bar falls within the first category and does not fall into either the second or the third category. Proper treatment might have saved the respondent’s leg, but, according to the medical experts, in view of the severe pre-existing atherosclerosis in her leg, she likely would have lost her leg in any event. The appellant’s negligence was not a necessary cause to bring the case within the second category, nor could the appellant’s negligence alone have been a sufficient cause to bring the case within the third category.

In my view, the respondent established no more than the loss of a less than 50 per cent chance of salvaging her leg had the appellant not been negligent. Unfortunately for the respondent, under the current state of the law, loss of a chance is non-compensable in medical malpractice cases: see Laferriere v. Lawson, [1991] 1 S.C.R. 541, 78 D.L.R. (4th) 609; St-Jean v. Mercier, [2002] 1 S.C.R. 491, 209 D.L.R. (4th) 513; Hotson v. East Berkshire Area Health Authority, [1987] A.C. 750 (H.L.). The trial judge did not explain the basis for her conclusion that "the loss of chance doctrine is not applicable to this case" [para.72]. In view of the evidence I have reviewed, and in view of the respondent’s concession that there was no evidence to suggest that it was more than likely a better outcome would have followed had the appellant acted with care, the trial judge’s finding reveals either a misapprehension as to the law or a palpable and overriding error on the facts.

Application for leave to appeal Cottrelle to the Supreme Court of Canada was denied at [2003] S.C.C.A. No. 549.

Adoption of St-Jean v. Mercier and Cottrelle in British Columbia

In McClelland v. Zacharias (2004), B.C.S.C. 1077, the court dismissed a medical negligence claim, noting that, "It is not enough to show that earlier treatment ‘might’ have avoided the plaintiff’s present condition," and cited with approval Cottrelle v. Gerrard. The rejection of the expansion of the material contribution test was upheld by our Court of Appeal in Mooney v. Canada (Attorney General), [2004] B.C.J. No. 1566 leave to S.C.C. denied at [2004] S.C.C.A. No. 428.

In the recent case of Seatle (Guardian ad Litem of) v. Purvis, [2005] B.C.S.C. 1567, Garson J. relied upon Cottrelle v. Gerrard in dismissing a medical negligence claim for failing to establish causation on a balance of probabilities. In Seatle, the infant plaintiff suffered shoulder dystocia during childbirth. The infant plaintiff alleged that the defendant physician should have anticipated shoulder dystocia and consulted with a specialist. Had the defendant consulted with a specialist, the infant plaintiff says that the outcome may have been different. The defendant argued that, even if a specialist had been consulted, there was no evidence establishing the necessary causal link between the failure to consult and the infant plaintiff’s injuries.

With respect to causation, the plaintiffs argued that, while the generally accepted test for causation is the "but for" test, the Supreme Court of Canada in Athey v. Leonati determined that, in circumstances where the "but for" test is unworkable, the courts have recognized that causation is established where the defendant’s negligence "materially contributed" to the occurrence or injury. The plaintiffs further argued that if it could be said that the defendant, by her breach of duty, created a material risk that a particular type of damage could occur, it is open to the court to infer that the risk materialized if the exact type of damage occurs absent evidence to the contrary. In essence, the plaintiffs argued that the material contribution test in Athey v. Leonati could be met by demonstrating a material risk of harm which in fact materialized. The court did an extensive review of the causation jurisprudence in Canada and concluded from reviewing the authorities that there were four possible theories of causation available to the plaintiff:

I conclude from reviewing these authorities that there are four possible theories of causation available to this plaintiff. At the risk of oversimplification, I would summarize these theories as follows:

1. The plaintiff must prove that "but for" the negligence of the defendant no injury would have occurred. This test should not be applied too rigidly, which means that an inference of causation may be made even in the absence of conclusive, precise, scientific evidence (Snell).

2. Where there are multiple possible causes of an injury, but the plaintiff can prove the defendant’s negligence materially contributed to the injury, liability for the whole loss, subject to claims of contribution, will attach to the defendant (Athey).

3. If the plaintiff can establish that the defendant materially increased the risk of a specific injury, and that specific injury occurs, the court may infer on a sufficient evidentiary basis that the material increase in risk was a contributing cause of the injury such that causation is established (Levitt, Webster). "The evidence is to be applied according to the proof which it was in the power of one side to have produced." (Snell).

4. The House of Lords has held that there may be a reversal in the burden of proof for causation such that if a plaintiff establishes that the defendant created an area of risk and the injury occurred in that area, the defendant must show that the injury had some other cause in order to escape liability (McGhee). This theory has not been applied in Canada and seems to have been restricted in England to toxic exposure cases.

Garson J. determined that there was insufficient evidence to conclude on a balance of probabilities that "but for" the absence of a consultation, the infant plaintiff would have been delivered sooner and the injury would not have occurred. With respect to the material contribution test, Garson J. noted that she accepted that if the defendant had consulted a specialist, the result might have been better, but there was no evidence establishing this fact on a balance of probabilities. Garson J. rejected the contention that causation could be established on less than a balance of probabilities by drawing an inference of evidence from the material increase in risk, noting that courts in both Ontario and Alberta have rejected finding that a "material increase in the risk of harm" satisfies the material contribution test. She noted that:

My findings that Dr. Thomas might have been able to deliver the baby faster and the outcome of the delivery might have been better had Dr. Thomas been present constitute an insufficient evidentiary basis on which to infer that his absence caused the oxygen deprivation, absent any testimony from Dr. Thomas, or any other expert that they would have handled the delivery differently.

Garson J. noted that in reality, the argument put forward by the plaintiff was that she lost her chance of a better outcome by the defendant’s failure to consult with a specialist. Garson J. noted that the law in Canada and in the United Kingdom does not attach liability to a defendant upon proof of a loss of chance [less than 50 percent] of a better outcome.

Conclusions on Material Contribution

The material contribution test should only be applied when the "but for" test is unworkable and, in the medical negligence context, should generally only be applied in circumstances where the plaintiff’s injury is caused by the cumulative effect of two or more factors, at least one of which is tortious. The material contribution test requires proof, on a balance of probabilities, that the tortious act was a factor, above the "de minimus", in causing the plaintiff’s injury. The material contribution test is generally not applicable in situations involving a delay in diagnosis or treatment; these situations are more appropriately analyzed using the loss of chance analysis.