In this blog, I’ll be discussing one of the six elements that are present while establishing a cause of action for negligence against a defendant. I’ve previously discussed the six elements in another blog, which will entitle you to commence a tort action in the Superior Court of Justice in Ontario, and they are as follows:

1. Breach of standard of care;

2. Sustaining actual damage;

3. Causation;

4. The existence of a duty of care;

5. Proximate cause and remoteness; and

6. Contributory negligence.

If you want to learn more about the six elements of a cause of action for negligence, then please click the “link” to read my blog entitled “What is the Cause of Action for a Negligence Action in Tort?”

In this blog I’ll take a deep dive into the third element, causation, where as the plaintiff, you must prove that the damage you suffered was caused by the negligence of the defendant. Therefore, I’d have to prove on your behalf that there exists a causal link or nexus between the tortfeasor’s or defendant’s negligent conduct or behaviour and the loss or damage you suffered, which is nominally known as the “cause-in-fact” issue in a negligence action.

The key element that more times than not is the primary focus in the legal analysis, which easily takes up the most time, and is the most contentious in establishing a cause of action for negligence against a defendant, is ascertaining the appropriate standard of care required of the defendant. However, in personal injury tort actions against an at-fault driver, the most contentious element is more times than not, the cause-in-fact issue.

If you want to learn more about the appropriate standard of care required by a lawyer, then please click the “link” to read my blog entitled “What’s the Standard of Care Required of a Lawyer?”

If you want to learn more about the appropriate standard of care required by a physician, then please click the “link” to read my blog entitled “What’s the Standard of Care Required of a Doctor?”

The cause-in-fact issue can become the most contentious issue in personal injury cases involving a motor vehicle accident, in particular, because sometimes there are numerous potential causes to the injuries and impairments, or the loss that you sustained. This occurs, for example, but not limited to, in the following circumstances:

1. You have been in multiple motor vehicle accidents within a close period of time to each other, where you suffered similar injuries and impairments, or aggravated or exacerbated similar injuries and impairments in all of the motor vehicle accidents;

2. You have a pre-existing condition or pre-existing injuries and impairments that are similar to the injuries and impairments that you sustained in the motor vehicle accident;

3. You sustain injuries and impairments from a separate, unrelated incident after the motor vehicle accident, which are similar to the injuries and impairments that you sustained from the motor vehicle accident; or

4. A combination of all of the above, which will compound the cause-in-effect issue.

In each of these circumstances, it could potentially be challenging to ascertain whether it was the motor vehicle accident that caused your serious and permanent injuries and impairments, or the other unrelated accidents in circumstance one, or your pre-existing condition and post-accident incident in circumstances two and three.

In law, when an individual’s negligent conduct or behaviour is the cause of the damages, or injuries and impairments, or the loss you sustained, we call this a tortious cause, because provided the other five aforementioned elements are present, you have a strong basis for establishing a cause of action against the negligent individual or tortfeasor.  However, when the cause of the damages, injuries and impairments, or the loss you sustained, is not the individual whom you have initiated a tort action against or is independent of the event that gave rise to the tort action, such as another unrelated motor vehicle accident, a pre-existing condition, or a post-accident incident, we call this a non-tortious cause, if these circumstances eliminate the basis for establishing a cause of action.

The general test for causation is what is nominally known as the “but for” test, further to the seminal Supreme Court of Canada case entitled Resurfice Corp. v. Hanke, 2007 SCC 7 (CanLII), [2007] 1 S.C.R. 333 at paragraphs 21 to 23, citing Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 S.C.R. 311 at paragraph 14, which requires you, as the plaintiff, to show that your injuries and impairments, or the loss, would not have occurred “but for” the negligence of the defendant.  In other words, the “but for” test places the burden of proof on you, the plaintiff, to demonstrate that “but for” the negligence of the defendant, you would not have suffered your injuries and impairments, or the loss.

However, in certain exceptional cases, the “but for” test will not apply, such as, but not limited to, cases with the following circumstances, further to paragraph 25 of Resurfice Corp. v. Hanke, supra, as follows:

• It is impossible for the plaintiff to prove that the defendant’s negligence caused the plaintiff’s injury using the “but for” test; and

• It is clear that the defendant breached a duty of care owed to the plaintiff and exposed the plaintiff to an unreasonable risk of injury, and the plaintiff must have suffered that injury.

These two aforementioned conditions are not just mutually inclusive, but they both have to exist at the same time.

The leading seminal case, when the “but for” test is unworkable, is the Supreme Court of Canada case entitled Athey v. Leonati, [1996] 3 S.C.R. 458, where on page 2 of the decision, the Supreme Court of Canada stated the following:

The general, but not conclusive, test for causation is the “but for” test, which requires the plaintiff to show that the injury would not have occurred but for the negligence of the defendant. 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 of the injury.

Therefore, the test to be applied by a court to determine the cause-in-fact issue is the “but for” test, but only if the “but for” test is not workable, then and only then, can the court apply what is nominally known as the material contribution test.

The Supreme Court of Canada in Athey v. Leonati, supra, eloquently explained the rational basis for the material contribution test in a classic rudimentary example, at paragraph 17, as follows:

To borrow an example from Professor Fleming (The Law of Torts (8th ed. 1992) at p. 193), a “fire ignited in a wastepaper basket is … caused not only by the dropping of a lighted match, but also by the presence of combustible material and oxygen, a failure of the cleaner to empty the basket and so forth”. As long as a defendant is part of the cause of an injury, the defendant is liable, even though his act alone was not enough to create the injury. 

An example of when the “but for” test would be unworkable is if your motor vehicle accident alone could have been a sufficient cause, and your pre-existing condition or non-tortious causes alone could have also been a sufficient cause, because then it is unclear which was the cause of the injuries and impairments, or the loss you claim to have sustained as a direct result of the motor vehicle accident. In this example where the “but for” test is unworkable, the court will apply the material contribution test, where the court will determine, on a balance of probabilities, whether the defendant’s negligence materially contributed to your injuries and impairments, or the loss.

The Supreme Court of Canada in Athey v. Leonati, supra addressed what constitutes a contributing factor to be material, at paragraph 15, as follows:

A contributing factor is material if it falls outside the de minimis range: Bonnington Castings, Ltd. v. Wardlaw; R. v. Pinske (1988), 30 B.C.L.R. (2d) 114 (B.C.C.A.), aff’d [1989] 2 S.C.R. 979.

Therefore, so long as the contributing factor of the defendant’s negligence falls outside of the de minimis range, then it is deemed to constitute a material contribution to the injuries and impairments, or the loss you suffered, irrespective of whether there were other non-tortious causes and pre-existing conditions that also constituted a contributing factor.

The Supreme Court of Canada commented on the de minimus range analysis at paragraph 44 in Athey v. Leonati, supra, and what must be proven to show material contribution, as follows:

The trial judge’s conclusion on the evidence was that “[i]n my view, the plaintiff has proven, on a balance of probabilities, that the injuries suffered in the two earlier accidents contributed to some degree to the subsequent disc herniation”. She assessed this contribution at 25 percent. This falls outside the de minimis range and is therefore a material contribution: Bonnington Castings, Ltd. v. Wardlaw, supra. This finding of material contribution was sufficient to render the defendant fully liable for the damages flowing from the disc herniation.

Therefore, so long as the contribution of the motor vehicle accident to your injuries and impairments, or the loss you suffered is assessed at 25 percent, then the contribution of the defendant’s negligence falls outside of the de minimis range. As such, the motor vehicle accident, which was caused by the defendant’s negligent conduct and behaviour, constitutes a material contribution to your injuries and impairments, or the loss you suffered, irrespective of the existence of other pre-existing conditions and non-tortious causes that also constituted a contributing factor.

On a plain reading of the “but for” test, it would seem that it requires you, the plaintiff, to establish that the defendant’s negligence was the sole cause of your injuries and impairments, or the loss, however, the Supreme Court of Canada, while providing a rational basis for the need to have the aforementioned material contribution test, reminded us that this not a necessary requirement in the case entitled Athey v. Leonati, supra, at paragraphs 17, 19 and 20, as follows:

It is not now necessary, nor has it ever been, for the plaintiff to establish that the defendant’s negligence was the sole cause of the injury. There will frequently be a myriad of other background events which were necessary preconditions to the injury occurring … There is no basis for a reduction of liability because of the existence of other preconditions: defendants remain liable for all injuries caused or contributed to by their negligence.

and

The law does not excuse a defendant from liability merely because other causal factors for which he is not responsible also helped produce the harm: Fleming, supra, at p. 200. It is sufficient if the defendant’s negligence was a cause of the harm: School Division of Assiniboine South, No. 3 v. Greater Winnipeg Gas Co., [1971] 4 W.W.R. 746 (Man. C.A.), at p. 753, aff’d [1973] 6 W.W.R. 765 (S.C.C.), [1973] S.C.R. vi; Ken Cooper-Stephenson, Personal Injury Damages in Canada (2nd ed. 1996), at p. 748.

and

This position is entrenched in our law and there is no reason at present to depart from it. If the law permitted apportionment between tortious causes and non-tortious causes, a plaintiff could recover 100 percent of his or her loss only when the defendant’s negligence was the sole cause of the injuries. Since most events are the result of a complex set of causes, there will frequently be non-tortious causes contributing to the injury. Defendants could frequently and easily identify non-tortious contributing causes, so plaintiffs would rarely receive full compensation even after proving that the defendant caused the injury. This would be contrary to established principles and the essential purpose of tort law, which is to restore the plaintiff to the position he or she would have enjoyed but for the negligence of the defendant.

Therefore, one of the primary guiding principles behind the awarding of compensatory damages in common law negligence claims is captured in the term restitio ad integrum or restitutio in integrum, which is a Latin term that means restoration to original condition, or to restore you to the position you would have enjoyed “but for” the negligence of the defendant. Since this purpose would never be achieved if the law required the defendant’s negligence to be the sole cause of your injuries and impairments, or the loss, it has become entrenched in our law that the defendant could still be held 100% liable even if there are, as is often the case, a myriad of other background events, and a complex set of pre-conditions and non-tortious causes to the damages you sustained. So, if you, as the plaintiff, are able to prove on a balance of probabilities that the defendant’s negligent act materially contributed to your injury and impairment, or loss complained of, in a manner that falls outside of the de minimis range, then you satisfy the onus of proving causation, further to Kersey v. Wellesley Hospital [1988] 46 C.C.L.T. 271 (Ont.H.C.J.). As such, there would be no basis for a reduction of liability because of the existence of other preconditions and non-tortious causes, so the defendant would remain liable for all of your injuries and impairments, or the loss caused or contributed to by the defendants negligence, further to Cork v. Kirby MacLean Limited [1952] 2 All E.R. 402 (C.A.) and Athey v. Leonati, supra.

The legal or ultimate burden to prove causation remains with you, as the plaintiff, although positive or scientific proof of causation is not required. In the Supreme Court of Canada case entitled Laferriere v. Lawson (1991), 78 D.L.R. (4th) 609 (S.C.C.), Gonthier J. confirmed the principles concerning the burden of proof of causation, as set out in Snell v. Farrell, supra, as follows:

(a) causation in law does not require scientific causation;

(b) causation in law must be established on the balance of probabilities, taking into account all of the evidence: factual, statistical and that which the judge is entitled to presume;

(c) 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; and

(d) even where statistical and factual evidence do not support a finding of causation on the balance of probabilities with respect to particular damage, such evidence may justify a finding of causation with respect to lesser damage.

The Supreme Court of Canada in Athey v. Leonati, supra, also commented on how rigid the application of the causation test needs to be, at paragraph 16, as follows:

In Snell v. Farrell, supra, this Court recently confirmed that the plaintiff must prove that the defendant’s tortious conduct caused or contributed to the plaintiff’s injury. The causation test is not to be applied too rigidly. Causation need not be determined by scientific precision; as Lord Salmon stated in Alphacell Ltd. v. Woodward, [1972] 2 All E.R. 475, at p. 490, and as was quoted by Sopinka J. at p. 328, it is “essentially a practical question of fact which can best be answered by ordinary common sense”. Although the burden of proof remains with the plaintiff, in some circumstances an inference of causation may be drawn from the evidence without positive scientific proof.

Therefore, the court can draw an inference of causation from the defendant’s alleged negligence by applying common sense to the evidence I’d present for you on your behalf, or in the absence of evidence to the contrary adduced by the defendant. However, remember that even if the defendant in your tort action provides some evidence to the contrary, that evidence will be weighed by the court against the evidence I present on your behalf, and as a result, causation can still be inferred further to Blatch v. Archer [1774] 98 E.R.969, as cited in Snell v. Farrell [1990] 2 S.C.R. 311).

If you have suffered from previous injuries, impairments or pre-existing conditions before your motor vehicle accident that’s at issue, then the question is whether your motor vehicle accident caused permanent, serious impairments of an important function, when compared to your condition immediately before your motor vehicle accident, further to Austin-Cooke v. Reid, 2005 CarswellOnt 7923 (S.C.J.) and Chrappa v. Ohm, 1996 CarswellOnt 1743, [1996] O.J. No. 1663 (S.C.J.).

In a case entitled Briggs v. Maybee, [2001] O.J. No. 941 (S.C.J.), Mr. Briggs was injured in an automobile accident, but had suffered from many pre-accident conditions, including Crohn’s Disease and kidney malfunction, such that at the time of his accident he was on CPP disability benefits and his activities were seriously limited. Belch, J. said at para. 29, the following:

Is the injury one that has created a permanent serious impairment of important physical, mental or psychological functions? Again, the medical evidence presented at trial has suggested the injury is permanent. To decide whether it is serious to this plaintiff, one must look at how it has affected his life. Acknowledging he was on CPP disability prior to the accident, he was already functioning at a level far below what a usual healthy person would enjoy. He could only participate in activities at his own pace, and while those activities may not be seen as significant to others who enjoy a more active lifestyle, free of disability, this injury has further marginalized the existence of this plaintiff and has had a serious physical and psychological impact on the future enjoyment of his life. He cannot lift his son, cut grass, shovel snow, or do some of the housework. These had been his contributions to the marriage, given his disabilities.

In other words, the court will measure the seriousness of your impairment and the importance of your bodily function against your ability and function immediately before your motor vehicle accident. Assuming that your motor vehicle accident caused an injury and impairment that adversely affects your physical, mental or psychological function, depending on your pre-accident limitations, it may not take much further impairment for your accident-caused-impairment to be serious and the function important.

If you want to learn more about what constitutes a serious and permanent impairment, and the legislative threshold that must be satisfied in order to obtain general non-pecuniary damages – pain and suffering – in a tort action, then please click the “link” to read my blog entitled “What Damage Awards Do I Get from a Successful Tort Action?”

Of note, is the distinction between the assessment of causation, which deals with the past, and contingencies, which deals with the future. The Supreme Court of Canada in Athey v. Leonati, supra, noted the distinction at paragraphs 28 and 29, as follows:

By contrast, past events must be proven, and once proven they are treated as certainties. In a negligence action, the court must declare whether the defendant was negligent, and that conclusion cannot be couched in terms of probabilities. Likewise, the negligent conduct either was or was not a cause of the injury. The court must decide, on the available evidence, whether the thing alleged has been proven; if it has, it is accepted as a certainty: Mallet v. McMonagle, supra; Malec v. J.C. Hutton Proprietary Ltd., supra, Cooper-Stephenson, supra, at pp. 67-81.

and

The role of the court in making an assessment of damages which depends upon its view as to what will be and what would have been is to be contrasted with its ordinary function in civil actions of determining what was. In determining what did happen in the past a court decides on the balance of probabilities. Anything that is more probable than not it treats as certain. But in assessing damages which depend upon its view as to what will happen in the future or would have happened in the future if something had not happened in the past, the court must make an estimate as to what are the chances that a particular thing will or would have happened and reflect those chances, whether they are more or less than even, in the amount of damages which it awards.

Therefore, when the court is assessing the cause-in-fact issue in your tort negligence action against the defendant, which deals with the past, it will not do so in varying degrees of probability, but rather conclude whether the negligent conduct was not or was the cause of your injuries and impairments, or the loss, as a certainty. If the negligence of the defendant caused or contributed to injuries and impairments, or the loss you sustained in your motor vehicle accident, then the defendant is fully liable for the damages flowing from your injuries and impairments, or the loss. Again, you, as the plaintiff, must prove causation by meeting the “but for” or in the alternative, if the “but for” test is unworkable, the material contribution test. Furthermore, future or hypothetical events can be factored into the calculation of compensatory damages according to degrees of probability, but the causation of your injuries and impairments, or the loss, must be determined to be proven or not proven as a certainty.

The Supreme Court of Canada in Athey v. Leonati, supra, also noted the factors that a court, upon determining the negligent conduct of the defendant caused your injuries and impairments, must take into account to either (1) not unfairly reduce you compensatory damage award due to a pre-existing condition, or (2) reduce your overall award in order to not unfairly punish the defendant by putting you in a better position than you were in prior to your motor vehicle accident. At paragraphs 34 and 35, respectively, of the Athey v. Leonati, supra, decision, the Supreme Court of Canada, further elucidated the distinction between the well-known thin skull and crumbling skull rules, as follows:

…the “crumbling skull” doctrine is an awkward label for a fairly simple idea. It is named after the well-known “thin skull” rule, which makes the tortfeasor liable for the plaintiff’s injuries even if the injuries are unexpectedly severe owing to a pre-existing condition. The tortfeasor must take his or her victim as the tortfeasor finds the victim, and is therefore liable even though the plaintiff’s losses are more dramatic than they would be for the average person.

and

The so-called “crumbling skull” rule simply recognizes that the pre-existing condition was inherent in the plaintiff’s “original position”. The defendant need not put the plaintiff in a position better than his or her original position. The defendant is liable for the injuries caused, even if they are extreme, but need not compensate the plaintiff for any debilitating effects of the pre-existing condition which the plaintiff would have experienced anyway. The defendant is liable for the additional damage but not the pre-existing damage: Cooper-Stephenson, supra, at pp. 779-780 and John Munkman, Damages for Personal Injuries and Death (9th ed. 1993), at pp. 39-40. Likewise, if there is a measurable risk that the pre-existing condition would have detrimentally affected the plaintiff in the future, regardless of the defendant’s negligence, then this can be taken into account in reducing the overall award: Graham v. Rourke, 74 D.L.R. (4th) 1; Malec v. J.C. Hutton Proprietary Ltd., 169 C.L.R. 638; Cooper-Stephenson, supra, at pp. 851-852. This is consistent with the general rule that the plaintiff must be returned to the position he would have been in, with all of its attendant risks and shortcomings, and not a better position.

Therefore, the balance of compensatory fairness between you and the negligent at-fault driver, is also expressed in these two legal principles and rules: (1) the “thin skull” rule; and (2) the “crumbling skull” rule. Further to the thin skull rule, the negligent at-fault driver is liable for your accident-related injuries and impairments, even if they are unexpectedly severe owing to a pre-existing condition. So, the negligent at-fault driver must take you, the victim, as he or she  finds you, and is therefore liable even though your losses are more dramatic than they would be for the average person. However, it’s balanced out by the crumbling skull rule, which recognizes that your pre-existing condition was inherent in your “original position”. Therefore, the negligent at-fault driver need not put you in a position better than your original position. The negligent at-fault driver is liable for the injuries caused, even if they are extreme, but need not compensate you for any debilitating effects of your pre-existing condition, which you would have experienced anyway. The negligent at-fault driver is liable for the additional damage, but not the pre-existing damage.

If your motor vehicle accident alone could have been a sufficient cause, and your pre-existing condition or non-tortious causes alone could have been a sufficient cause, then it is unclear which was the cause-in-fact of the injuries and impairments you claim to have sustained as a direct result of the motor vehicle accident.  The trial judge must determine, on a balance of probabilities, whether the defendant’s negligence materially contributed to your injuries and impairments, or the loss.

I hope you found this information valuable. Rudder Law Group’s website is your one-stop source for answers to all of your legal questions concerning catastrophic impairment law and personal injury law.