If I have pre-existing conditions that become symptomatic due to my crash injuries, am I entitled to damages? How does a court decide what to attribute to the crash?
In a decision released on September 20, 2016 (Chappell v. Loyie 2016 BCSC 1722), the British Columbia Supreme Court was asked to assess the damages resulting from a crash between a motorcycle and car. The motorcyclist (Mr. Chappell) was proceeding on a green light, when the car (driven by Mr. Loyie) crossed his path while attempting a left turn. Mr. Chappell was thrown from his motorcycle, and suffered significant injuries including a mTBI, severe depression and anxiety, soft tissue injuries to the feet, ankles, back and neck, headaches, carpal tunnel syndrome, injury to a previously reconstructed right knee ACL, and a right shoulder rotator cuff injury. He also later developed pain in his left shoulder, and his left knee. Determination of the cause of his injuries and symptoms was greatly complicated by the fact that he had pre-existing conditions that became symptomatic after this crash.
Before parsing out which injuries and symptoms were attributable to the crash, Madam Justice Fisher summarized the “but for” test, noting that the plaintiff (Mr. Chappell) was not required to establish that the defendant’s (Mr. Loyie’s) negligence was the sole cause of his injuries. She noted that “in short, the essential purpose of tort law is to restore the plaintiff to the position he would have enjoyed but for the negligence of the defendants”. She went on to overview the law is it relates to causation and pre-existing conditions:
 As the court said in Blackwater, a plaintiff is only to be restored to his original position, and not a better position. A defendant is not required to compensate a plaintiff for any debilitating effects arising from a pre-existing condition that the plaintiff would have experienced anyway, and if there is a measureable risk that the pre-existing condition would have detrimentally affected the plaintiff in the future, regardless of the defendant’s negligence, this is to be taken into account in reducing the overall award: Athey, at para. 35; Moore v. Kyba, 2012 BCCA 361 at para. 43. In addition, damages caused by other non-tortious causes that occur after the defendant’s wrongful act must be taken into account: Blackwater, at para. 80. This is referred to as the “crumbling skull” doctrine. It is important to note that any reduction made to take these factors into account does not reduce the damages; it simply awards the damages which the law allows: see Blackwater, at para. 84.
 In addition, a tortfeasor is liable for a plaintiff’s injuries even if the injuries are unexpectedly severe owing to a pre-existing condition. As the court said in Athey, at para. 34, the tortfeasor must take the victim as he finds him, and is liable even though the plaintiff’s losses are more dramatic than they would be for the average person. This is known as the “thin skull rule”.
 There has been some confusion in the law with respect to these labels. In A. (T.W.N.A.) v. Canada (Ministry of Indian Affairs), 2003 BCCA 670, the court clarified this at para. 30 by stating that the “simple idea” expressed in Athey, was clear and direct and “both latent and active pre-existing conditions must be considered in assessing the plaintiff’s original position.” At para. 48:
…Whether manifest or not, a weakness inherent in a plaintiff that might realistically cause or contribute to the loss claimed regardless of the tort is relevant to the assessment of damages. It is a contingency that should be accounted for in the award. Moreover, such a contingency does not have to be proven to a certainty. Rather, it should be given weight according to its relative likelihood.
 Hypothetical and future events – how the plaintiff’s life would have gone without the tortious injury – need not be proven on a balance of probabilities. They are given weight according to their relative likelihood, or the probability of their occurrence. A future or hypothetical possibility is to be taken into account “as long as it is a real and substantial possibility and not mere speculation”: Athey, at para. 27.
She went on to a lengthy assessment of which injuries were caused by the crash. She concluded that all complaints other than right shoulder pain and right knee pain (the onset of each being well over a year post-crash) were caused by the crash. She awarded $150,000.00 for pain and suffering, wage loss for the two years leading up to trial (despite carrying on with his work as a firefighter for 2.5 years post-crash), a loss of earnings associated with “under the table” earnings for construction work (complicated by his failure to report those earnings to the CRA), and a future loss of earning capacity for both firefighting and under the table earnings. In total, he was awarded over $1.1M despite the complexities posed by his pre-existing conditions.