Barkley v. Sloan, 2025 ONSC 6057 offers an important reminder that catastrophic (CAT) impairment is not a matter of intuition, narrative medical opinions, or hindsight logic. It is a technical medical-legal determination governed by strict statutory and methodological requirements and calculations. Justice Nightingale’s decision illustrates just how rigorously courts will enforce those requirements, especially when a plaintiff attempts to prove a “lost opportunity” to be found catastrophically impaired after settling their accident benefits claim.
Ms. Barkley, the plaintiff, was injured in a 2012 accident and later sued her former lawyer alleging that he provided negligent legal advice. Although Justice Nightingale’s decision centred around these allegations of professional negligence, much of the decision was devoted to evaluating expert evidence on CAT impairment. Ms. Barkley’s theory was, but for her lawyer’s advice, she could have been found catastrophically impaired under two pathways: the 55% whole person impairment (WPI) test and the mental/behavioural “marked impairment” test. The first requires a combined impairment rating of 55% or higher in accordance with the American Medical Association (AMA) Guides. The second required a “Class 4” marked impairment in at least one domain of mental or behavioural functioning.
Expert Witnesses
Two experts reviewed the medical evidence: Dr. Persi, a chiropractor who conducts impairment assessments, and Dr. Gnam, a psychiatrist. Justice Nightingale gave little weight to Dr. Persi’s evidence. As Dr. Gnam explained, and the court accepted, Dr. Persi, as a chiropractor, was not qualified to diagnose mental disorders, assign psychological impairment ratings, or provide WPI calculations that included mental or behavioural components. Under the AMA Guides and the Statutory Accident Benefit Schedule (SABS), these tasks fall squarely within the expertise of physicians (except in the narrow case of traumatic brain injuries, which was not the case here).
Beyond their qualifications, the bigger issue between the experts was methodological. Dr. Persi conducted a retrospective assessment based on selected medical summaries, not full treatment records, and his impairment ratings repeatedly lacked evidentiary support. He assigned a 5% WPI for headaches even though no neurologist diagnosed accident-related headaches, and the treating physicians did not document persistent headaches in the relevant period. He also assigned an additional 3% rating for chronic pain despite the fact that the AMA Guides already incorporate pain into other system ratings. His 9% rating for sleep disturbance was also rejected because the table he used applied only to sleep issues arising from brain injuries.
Another issue was that Dr. Persi consistently chose the highest number available within every AMA range. 29% for psychological impairment, 9% for sleep disturbance, and so on. He argued that assessors should provide claimants the benefit of the doubt. However, case law has repeatedly dismissed this “generous” interpretation. The AMA Guides require precision, not generosity. Justice Nightingale found that Dr. Persi’s approach functioned as advocacy, not objective assessment.
By contrast, Dr. Gnam relied on accepted methodology and used the AMA Guides the way they are intended to be used. Even if the judge had generously accepted Dr. Persi’s 28% rating for Ms. Barkley’s left upper extremity (which itself was questionable), the combined physical and psychological ratings still fell around 49–50%, below the 55% threshold.
Ms. Barkley also argued that she would have been catastrophically impaired under the mental/behavioural test, but the evidence simply didn’t support it. Dr. Persi asserted that she had marked impairments in concentration, persistence, pace, and adaptation to work. But both mental health experts Dr. McKay, a neuropsychologist, and Dr. Gnam, a psychiatrist, found that her impairments were moderate, not marked. They made note of her ability to continue working part-time, her functional level in daily activities, and the absence of the kind of substantial functional breakdowns typically associated with Class 4 impairments. Even Dr. Persi’s own psychological WPI rating placed her squarely within the “moderate” category, contradicting his claim of marked impairment.
Justice Nightingale ultimately determined that Ms. Barkley had failed to establish on a balance of probabilities that she would have qualified as catastrophically impaired under either test. This wasn’t a judgment on the severity of her injuries; the court accepted that they were definitely significant. The issue was the evidence. CAT impairment is a technical legal designation, and it must be proven through qualified experts using the proper assessment framework and defensible, medically supported calculations. Without that type of reliable system, the court could not rule that she would have been deemed catastrophically impaired.
The takeaway is clear. For catastrophic impairment analysis, the expert evidence has to be clear, qualified, and grounded in the right framework.
Noah Waisglass is an articling student at ZTGH and is the author of this blog. If you have a question about this decision or a similar file, please reach out to Noah at [email protected].
