CanadaDo I need expert medical evidence to prove I suffered a mental injury?
No, you do not need expert medical evidence to prove a mental injury in Canada. The Supreme Court of Canada ruled in Saadati v. Moorhead that a recognized psychiatric diagnosis is not required — credible lay evidence can be sufficient.
What the Law Says
Canadian tort law does not impose a special evidentiary requirement for mental injury claims. There is no statutory provision mandating expert medical evidence or a formal psychiatric diagnosis to establish compensable mental injury.
Unlike some other jurisdictions, Canadian law treats mental injury the same as physical injury for purposes of proof in negligence claims.
The burden remains on the plaintiff to prove, on a balance of probabilities, that the defendant’s negligence caused a serious and prolonged mental disturbance — but no statute prescribes how that must be shown.
No federal or provincial statute requires expert testimony or a DSM diagnosis to establish mental injury in civil litigation.
What Courts Have Said
The Supreme Court of Canada fundamentally changed how mental injury is proven in civil cases.
The Court held that plaintiffs need not present expert medical evidence or prove a recognized psychiatric illness to recover for mental injury. Credible lay witness testimony — including from family, friends, or the plaintiff — may be sufficient to establish the existence, cause, and severity of a mental injury on a balance of probabilities.
What to Do
Gather consistent, credible lay evidence (e.g., testimony from family, employers, or therapists about changes in behaviour, mood, or function)
Document symptoms over time (journals, emails, medical visits — even without formal diagnosis)
Consider obtaining expert evidence if available — it strengthens your case but is not legally required
Work with a lawyer to frame lay evidence persuasively around the legal test: serious, prolonged, and causally linked to the defendant’s negligence
Sources
Same Question, Other Jurisdictions
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South KoreaNot legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-06-08.