The law of ‘causation’ was discussed extensively in reasons for judgment released today by the BC Court of Appeal.
Today’s case (Chambers v. Goertz) involved the appeal of the trial judge’s findings of liability. At trial the court found a taxi driver partially responsible for a crash for leaving his high-beams on which made it difficult for another motorist to see various Plaintiffs crossing a street. The other motorist then struck the Plaintiffs causing injuries. (Click here to read my post on the trial judgment).
The taxi driver appealed this finding arguing that “the trial judge erred in law in finding that his conduct was a ‘contributing cause’ of the plaintiffs injuries“.
This appeal was dismissed and the trial judgment was upheld. In dismissing the Appeal the BC Court of Appeal discussed the law of Causation in personal injury actions, specifically what the law requires for there to be a compensable relationship between the wrong act and injury to the victim.
The Court summarized this area of law as follows:
 The Supreme Court’s other use of “material contribution” is seen in Athey v. Leonati,  3 S.C.R. 458, 140 D.L.R. (4th) 235,  1 W.W.R. 97, where Major J., writing for the Court, held in the following passage that causation will be established if it is shown that the defendant’s negligence “materially contributed” to the occurrence of the plaintiff’s injury:
The “but for” test is unworkable in some circumstances, so the courts have recognized that causation is established where the defendant’s negligence “materially contributed” to the occurrence of the injury: Myers v. Peel County Board of Education,  2 S.C.R. 21, Bonnington Castings, Ltd. v. Wardlaw,  1 All E.R. 615 (H.L.);McGhee v. National Coal Board, supra. A contributing factor is material if it falls outside the de minimis range: Bonnington Castings, Ltd. v. Wardlaw, supra; see also R. v. Pinske(1988), 30 B.C.L.R. (2d) 114 (B.C.C.A.), aff’d  2 S.C.R. 979.
] 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. …
 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. 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. 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.
This proposition has long been established in the jurisprudence. Lord Reid stated in McGhee v. National Coal Board, supra, at p. 1010:
It has always been the law that a pursuer succeeds if he can shew that fault of the defender caused or materially contributed to his injury. There may have been two separate causes but it is enough if one of the causes arose from fault of the defender. The pursuer does not have to prove that this cause would of itself have been enough to cause him injury.
[Emphasis in original]
 As this passage illustrates, every injury has multiple necessary or “but for” factual causes. The function of tort law is to identify those for which the defendant should be held responsible. Thus, in Snell v. Farrell,  2 S.C.R. 311, 72 D.L.R. (4th), 4 C.C.L.T. (2d) 229, Sopinka J., writing for the Court, said, at 326,
Causation is an expression of the relationship that must be found to exist between the tortious act of the wrongdoer and the injury to the victim in order to justify compensation of the latter out of the pocket of the former.
 For purposes of determining whether a breach of duty was a “but for” cause of particular harm, there are no degrees of causation – specific conduct was either necessary for the harm to occur or it was not. However, not every cause necessary for the harm to occur can reasonably be considered a candidate for liability. For example, in this case, the accident would not have occurred but for the taxi company dispatcher’s sending Mr. Ahmad to respond to Ms. McDonald’s call, but no one would suggest that the dispatcher should be found liable for what happened. Therefore the law takes cognizance only of those causes that play a significant role in bringing about the outcome.
 This concept has been expressed in different ways. As I have noted, in Athey v. Leonati, the Court said at para. 15 that “causation is established where the defendant’s negligence ‘materially contributed’ to the occurrence of the injury”, and that a “material contribution” is one that “falls outside the de minimis range”. To similar effect the Court said, inSnell v. Farrell, at 327, that proof of causation requires “a substantial connection between the injury and the defendant’s conduct”. “Substantial connection” was also used to describe this idea in R. v. Goldhart,  2 S.C.R. 463 at 480, 136 D.L.R. (4th) 502, 107 C.C.C. (3d) 481, where the Court said,
The happening of an event can be traced to a whole range of causes along a spectrum of diminishing connections to the event. The common law of torts has grappled with the problem of causation. In order to inject some degree of restraint on the potential reach of causation, the concepts of proximate cause and remoteness were developed. These concepts place limits on the extent of liability in order to implement the sound policy of the law that there exist a substantial connection between the tortious conduct and the injury for which compensation is claimed. …
 Clearly, the “material contribution” test discussed in Resurfice Corp. v. Hanke has nothing to do with the circumstances of this case. Here, it was not impossible for the plaintiffs to prove causation. Rather, whether the breaches of duty of the parties played legally significant causal roles in the outcome was in each case a question of fact to be answered by rational inference drawn in the usual way from the evidence. Causation is essentially “a practical question of fact which can best be answered by ordinary common sense”: Snell v. Farrell at 328, citing Alphacell Ltd. v. Woodward,  2 All E.R. 475 at 490 (per Lord Salmon).
 It was this conventional “but for” test of causation that the trial judge applied when she held that Mr. Ahmad’s breach of duty was a “contributing cause” of the accident and that he was therefore liable. Her use of the phrase “contributing cause” signifies that she found as a fact that Mr. Ahmad’s conduct played an important enough role in the combination of events necessary for this occurrence to fix him with liability for the consequences. This was the correct approach in the circumstances and I would reject the submission that she erred in adopting it.