Introduction

This piece is a complement to one I wrote earlier this month, “A Primer in CAT Threshold: Where Case Law is Heading in Catastrophic Impairment Designations”^[1]. In it, I discussed the 3 distinct battlegrounds for catastrophic impairment at the LAT, namely traumatic brain injury, the 55% whole body impairment route, and mental/behavioral disorders.

This article takes aim at the last one.

What Criterion 8 Is—And Why It Matters

Under Ontario’s Statutory Accident Benefits Schedule (hereinafter “SABS”)^[2], a claimant is “catastrophically impaired” under Criterion 8 if, because of a mental or behavioural disorder, they have marked impairments in at least three of the four functional domains—activities of daily living, social functioning, concentration/persistence/pace, and adaptation—or an extreme impairment in one of those domains.

This post-2016 test applies to accidents on or after June 1, 2016 and is set out in s. 3.1(1)8 of O. Reg. 34/10.

The consequences to a claimant of a CAT finding under Criterion 8 are big.

A catastrophic designation immediately unlocks the lifetime combined cap of $1,000,000 for medical, rehabilitation, and attendant-care benefits, replacing the non-CAT combined ceiling of $65,000. Post-2016 SABS consolidated these categories into a single CAT pot. Expenditures on treatment, rehab goods/services, and attendant care all draw from that $1,000,000 fund^[3].

Within that combined limit, attendant care remains subject to monthly caps that are higher for CAT cases, up to $6,000 per month, provided the expense is reasonable/necessary and supported by a Form 1 from a qualified assessor^[4]. 

CAT status also restores housekeeping and home-maintenance benefits as a standard entitlement of $100 per week for as long as the impairment persists, whereas non-CAT claimants only access this head of loss if optional coverage was purchased^[5].

If the claimant was an unpaid primary caregiver pre-accident and can no longer perform those caregiving activities, the caregiver benefit becomes available on a CAT finding of  $250 per week for the first person in need of care and $50 per week for each additional person, subject to the SABS election rules (you cannot receive IRB/NEB and caregiver at the same time) and duration conditions^[6].

CAT designation also permits funding for a case manager, coordination that is generally unavailable in non-CAT files without optional benefits, again paid from the same combined $1,000,000 fund^[7].

Two common misconceptions are worth clearing up.

First, weekly income benefits (IRB) and non-earner benefits (NEB) are not enlarged by CAT status. Their quantum and tests are set elsewhere in the SABS and generally remain the same, though the caregiver election can displace NEB/IRB in appropriate CAT cases^[8].

Second, optional accident-benefit endorsements can increase the combined med/rehab/attendant-care limit (commonly to $2,000,000) or add housekeeping/caregiver for non-CAT cases, but those are contractual add-ons, not automatic consequences of a CAT finding^[9].

The bottom line is that CAT status doesn’t change every benefit, but it dramatically expands the treatment/rehab/attendant-care envelope, restores housekeeping and caregiver benefits, and unlocks case management. These are the levers that most often move settlement value in serious mental-behavioural cases.

Statutory Architecture and the AMA Guides

The 2016 reforms tethered catastrophic determinations to the AMA Guides framework and, for Criterion 8, retained a function-first, domain-based inquiry.

Crucially, the amendments raised the threshold from the pre-2016 regime so that the single “marked” pathway recognized before 2016 no longer suffices. Claimants must now prove three marked domains or one extreme. The text and structure of s. 3.1(1) reflect this deliberate tightening and continue to demand domain-specific evidence rather than global labels.

What “Marked” and “Extreme” Mean—And What Pastore Still Teaches

Although Pastore v. Aviva Canada Inc., 2012 ONCA 642^[10] interpreted the pre-2016 SABS and confirmed that a single marked impairment could trigger CAT then, the case remains instructive on how adjudicators should analyze functional loss, including the quality and sustainability of real-world functioning, the difference between impairment and disability, and the permissibility of considering pain within the mental/behavioural analysis.

The quantitative gateway has changed since 2016, but Pastore’s approach to evidence remains relevant today.

The Evidence That Moves the Needle

On modern files, the cases turn on granular, long-term, function-anchored proof. Treating-source notes, psychological and OT assessments tied explicitly to each domain, friends and family accounts, employer or school records, and objective anchors such as attendance logs, medication adherence, and crisis contacts carry more weight than conclusory reports. Adjudicators press on causation, namely whether post-accident deterioration is attributable to the MVA rather than unrelated stressors. They also focus on domain-by-domain justification rather than global descriptors. The parties who map evidence to each domain with specificity tend to control the narrative.

Appellate Backdrop: Deference to LAT Fact-Finding

The Supreme Court’s decision in Yatar v. TD Insurance Meloche Monnex, 2024 SCC 8^[11]underscores the narrow path for statutory appeals and confirms the continued role of judicial review, while emphasizing deference to fact-intensive administrative determinations. For Criterion 8 disputes, Yatar is a practical reminder that parties must build a careful record the first time, because pure fact-finding and mixed questions closely tethered to the evidence will be difficult to dislodge later.

Legislative and Procedural Anchors

The controlling text remains O. Reg. 34/10, s. 3.1(1)8^[12], as consolidated, and practitioners should ensure that assessment protocols, scopes of practice, and domain analyses are aligned to the post-2016 framework when they commission or challenge expert opinions. The regulation itself is the first and last word on mental and behavioral CAT designation,  and should be the lens through which any expert evidence is prepared and tested.

Important Recent LAT Criterion 8 Cases

The LAT pumps out decisions constantly. In terms of how the LAT is actually weighing evidence on Criterion 8, these four are the tightest, most instructive recent picks I have found.

In Simmons v. Belairdirect Insurance Company, 2023 CanLII 26935 (ON LAT)^[13], the Tribunal designated the applicant catastrophically impaired under Criterion 8, accepting three marked impairments supported by long-term clinical notes, detailed collateral evidence, and an OT situational assessment that captured dramatic decompensation under everyday stressors. Surveillance showing isolated outings was not treated as determinative. The LAT focused on domain-by-domain functional loss over snapshots.

The case of Abou-Gabal v. Economical Insurance Company, 2024 CanLII 77423 (ON LAT)^[14]is illuminating. Despite a complex pre-accident history and preliminary disputes about IE attendance, the LAT found the applicant met the catastrophic threshold on the strength of the record, emphasizing necessary causation and weighing the totality of the medical and functional evidence over gaps or inconsistencies in participation. The decision is a useful reminder that CAT determinations turn on sustained, real-world functioning tied to the SABS domains, not labels.

In Cyples v. Intact Insurance Company, 2025 CanLII 3778 (ON LAT)^[15],
the LAT clarified how to apply the three-marked / one-extreme standard post-2016. Adjudicators expect discipline-appropriate opinions that map evidence to each domain, with clear attribution to the accident. Conclusory “global” ratings carried little weight compared with reasoned, domain-specific analyses tied to daily functioning and collateral proof.

I also found Ortaugurlu v. Pembridge Insurance, 2025 CanLII 31124 (ON LAT)^[16] instructive. The Tribunal found CAT under Criterion 8 and, procedurally, admitted a late-served lay witness where prejudice was minimal. The case llustrates the LAT’s willingness to hear corroborative collateral evidence that speaks directly to ADLs, social function, CPP, and adaptation. Substantively, the decision underscores that consistent treating-source records and credible lay narratives from family and friends can carry decisive weight across the domains.

The Mediator’s Perspective

In the mediation room, Criterion 8 disputes resolve when the parties converge on credible, durable evidence of day-to-day incapacity across the requisite number of domains. A prudent approach is one that asks whether the claimant’s record genuinely establishes three marked domains—or one extreme—with defensible, domain-specific reasoning, whether the experts are properly qualified and stay within scope, and whether the claimed impairments are stable over time rather than snapshot-dependent.

Post-2016 thresholds make claimant wins rarer, but defendants face risk when a well-built, function-first record lands three marked impairments. Pragmatic settlements reflect that risk calculus by funding serious care and supports rather than spending the same dollars litigating domain arithmetic to the end.