Executive Summary: Key Legal and Evidentiary Issues

• Causation was the central legal issue, focusing on whether a minor collision could trigger long-term psychological and cognitive impairment.

• The plaintiff’s extensive pre-existing conditions, including Addison’s disease, complicated the medical causation analysis.

• Conflicting expert medical opinions raised doubt about whether the plaintiff suffered a concussion or had somatic symptom disorder.

• Non-expert testimony from family members played a key role in establishing the plaintiff’s post-accident decline.

• The court found the plaintiff’s impairments genuine but not fully attributable to the accident, warranting a significant reduction in damages.

• A 75% contingency discount was applied across all heads of damages to account for the likelihood that the plaintiff’s condition would have developed regardless of the incident.

Facts and outcome of the case

Background and facts

In this case, Kristina Mariotto sued the estate of the late Joan Rowntree for damages following a minor motor vehicle collision on July 6, 2018. The plaintiff was stopped in traffic when her vehicle was rear-ended at low speed. She initially appeared uninjured and did not seek medical attention immediately. However, in the weeks and months that followed, she began experiencing debilitating physical, cognitive, and emotional symptoms that she attributed to the accident.

Prior to the collision, Ms. Mariotto was an active individual with part-time employment in a dental office and her husband’s company. She also lived with several chronic health conditions, including Addison’s disease, hypothyroidism, and a history of migraines. Despite these, she maintained a relatively normal lifestyle. Her health sharply declined after the accident. She reported memory lapses, chronic fatigue, confusion, and pain, rendering her unable to work or engage in social or physical activities. Her husband and sister both testified to observing significant changes in her personality, behavior, and functioning shortly after the incident.

The defence contested the causal link between the accident and her alleged injuries, pointing to her complex medical history. Medical experts offered conflicting assessments. Some believed she had suffered a mild traumatic brain injury or post-concussion syndrome, while others doubted any concussion occurred and instead attributed her condition to pre-existing disorders. One psychiatrist diagnosed somatic symptom disorder, suggesting that her sincere belief in her symptoms, rather than physical injury alone, might explain her current state.

Causation and legal analysis

The court applied the “but for” test for causation, requiring the plaintiff to prove the accident was a necessary cause of her injuries. While the court accepted that the plaintiff was not malingering and that her impairments were real, it was not persuaded that the low-impact accident alone could have caused a concussion or traumatic brain injury. Justice Baird leaned toward the view of the defence neurologist, who considered the plaintiff’s symptoms “multifactorial” and likely related to her complex medical background.

Nonetheless, the court acknowledged that the accident may have acted as a psychological trigger, particularly for someone with pre-existing vulnerabilities. Given the sudden deterioration in her functionality post-accident and the absence of any other triggering event, the judge concluded that the collision was a contributing factor, but not the primary cause. He determined that even a minor incident could have set off the plaintiff’s symptoms due to her predisposition, but that her current condition would likely have emerged regardless of this specific accident.

Damages and award

Though the plaintiff sought over $1.6 million in damages, the court applied a substantial 75% reduction across all categories, finding that only 25% of her current condition could be fairly attributed to the accident. The total award came to $378,192.98. This included $50,000 in non-pecuniary damages, $82,040.50 in past wage loss, $156,993 for future loss of earning capacity, $84,749.25 for future care costs, and $4,410.23 in special damages. The court accepted that the plaintiff was largely unemployable but found the extent of the damages requested excessive given the uncertain causation.

Trial dates and counsel

The trial took place in Vancouver over two periods: January 27 to 31 and February 3 to 5, 2025. Judgment was issued on July 18, 2025. Kristina Mariotto was represented by A. Sayn-Wittgenstein and B. Souza. The defendant estate was represented by A. Spence and P. Pandher. Law firm affiliations were not identified in the judgment. Although the plaintiff succeeded in part, the matter of costs was left open for further determination if needed.

Conclusion

This decision illustrates how courts navigate complex personal injury claims involving plaintiffs with significant pre-existing conditions. While the plaintiff was found to be sincere and impaired, the court emphasized that defendants are not liable for unrelated medical conditions or inevitable declines in health. By applying a substantial contingency discount, the judgment balanced the principles of fairness and proportional liability in tort law.