This article will visit the topics of causation and intervening events, including the applicable law.
When an “intervening event” occurs in a personal injury matter, it may break the chain of causation. Take note that intervening events must be carefully analysed as they will create a negative contingency on a file. Damages will certainly be reduced by the Courts in proportion to the intervening event.
As noted in Farrant v. Laktin, 2011 BCCA 336 (CanLII) let’s review the applicable law on causation, including intervening events:
The Applicable Law on Causation
 To justify compensation for his disabling pain, the plaintiff must establish a causal connection between the defendant’s negligence and that pain.
 The general test for causation, established in Athey v. Leonati, 1996 CanLII 183 (SCC),  3 S.C.R. 458 at paras. 13-17, is the “but for” test: “but for” the accident, would the plaintiff have suffered the disabling pain? In Athey, the Court also stated that a plaintiff need not establish that the defendant’s negligence was the sole cause of the injury. If there are other potential non-tortious causes, such as the plaintiff’s spinal degeneration in this case, the defendant will still be found liable if the plaintiff can prove the accident caused or materially contributed to the disabling pain, beyond the de minimus range.
 In Resurfice Corp. v. Hanke, 2007 SCC 7 (CanLII), 1 S.C.R. 333, the Supreme Court affirmed the “but for” test remains the basic test for determining causation, but developed the concept of “material contribution” in a different manner than that used in Athey, formulating a “material contribution” test as an exception to the “but for” test, a matter that is not relevant to this appeal. The Court replaced the Athey definition of “material contribution” to the plaintiff’s injury with the concept of “a substantial connection” between the injury and the defendant’s conduct. These developments were usefully summarized by Mr. Justice Smith, writing for the majority, in Sam v. Wilson, 2007 BCCA 622 (CanLII) at para. 109:
“Material contribution”, as that phrase was used in Athey v. Leonati, is synonymous with “substantial connection”, as that phrase was used by McLachlin C.J.C. above in Resurfice Corp. v. Hanke. This causal yardstick should not be confused with the “material contribution test”. As McLachlin C.J.C. explained in Resurfice Corp. v. Hanke, at paras. 24 – 29, the “material contribution test” applies as an exception to the “but for” test of causation when it is impossible for the plaintiff to prove that the defendant’s negligent conduct caused the plaintiff’s injury using the “but for” test, where it is clear that the defendant breached a duty of care owed the plaintiff thereby exposing the plaintiff to an unreasonable risk of injury, and where the plaintiff’s injury falls within the ambit of the risk. …
 Thus, in applying the “but for” test, the trial judge was required to consider not just whether the defendant’s conduct was the sole cause of the plaintiff’s disabling pain, but also whether the plaintiff had established a substantial connection between the accident and that pain, beyond the de minimus level.
In T.W.N.A. v. Canada (Ministry of Indian Affairs), 2003 BCCA 670, the Court of Appeal reviewed the issue of intervening incident on the assessment of damages. The court said:
 Unrelated intervening events must be taken into account in the same way as pre-existing conditions. If such an event would have affected the plaintiff’s original position adversely in any event, the net loss attributable to the tort will not be as great and damages will be reduced proportionately (Athey v. Leonati ¶ 31-32).
…“independent intervening events” that would have affected the plaintiff’s original position adversely, must be reviewed and considered and if necessary, used to reduce the net loss attributable to the defendants’ negligence: Athey v. Leonati, at 31-32.
In addition, intervening events will impact the award under the category of past and future wage loss.
This principle is applicable not only to non-pecuniary damages but as well to damages for past or future loss or impairment of earning capacity.
We see a recent decision Friesen v Moo, 2018 BCSC 1866 (CanLII) in which the Plaintiff suffered injuries in 3 motor vehicle accidents. His non-pecuniary damages and income loss, however, were reduced due to the fact, among other events, that the Plaintiff had been later incarcerated and assaulted while in prison. The Court accepted that the events while incarcerated were deemed intervening, for which the Defendant could not be held responsible, thereby reducing these awards.
- Plaintiff must establish cause in fact connection between injury and defendant’s conduct
- Plaintiff must prove that “but for” the Defendants’ acts, the Plaintiffs damages would not have incurred
- The Defendant need not put the plaintiff in a better position than the position prior to the MVA
- The intervening event has broken the chain of causation between the defendants’ negligence and the plaintiff’s medical status
- The Plaintiff will not be excused if they acted unreasonably
- Plaintiff’s original position was affected by these events
- Events in prison exacerbated the Plaintiff’s symptoms
- The worsening of the Plaintiff’s injuries while in prison should result in a reduction in the quantum of the Plaintiff’s claims
The Court ultimately agreed with the defence arguments and stated the following:
 In the circumstances, I accept that some of the physical altercations in prison which resulted in blows to the plaintiff’s head, neck, and teeth worsened the plaintiff’s symptoms. I note that his recurrent headaches had abated for some time before he was struck on the head while in prison.
 I conclude that the physical assaults on the plaintiff when he was in prison adversely affected his physical condition in any event and there must [be] a proportionate reduction in his damages to reflect that fact so that the measure of damages the defendants must pay is adjusted.
The Plaintiff recovered the following awards:
$60,000 in non-pecuniary damages
$25,000 future income loss
$3,630 special damages and future care costs
MRI costs and costs to the Plaintiff
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