Mustapha v Culligan of Canada Ltd

Mustapha clarified the reasonable foreseeability requirement for psychiatric injury in negligence. The plaintiff's injury must be more than emotional upset or distress; it must rise to the level of recognisable psychiatric illness, and it must be reasonably foreseeable in a person of ordinary fortitude.

Mustapha discovered a dead fly in an unopened bottle of Culligan-supplied water. He developed major depressive disorder and other psychiatric injuries. He sued.

When is psychiatric injury actionable in negligence?

No liability. Injury was not reasonably foreseeable in a person of ordinary fortitude.

For negligence: injury must be reasonably foreseeable. For psychiatric injury, the plaintiff must establish (a) a recognisable psychiatric illness (not mere upset), and (b) that such injury was reasonably foreseeable in a person of ordinary fortitude. Once the threshold is crossed, the thin-skull rule applies.

McLachlin CJ held that the law assumes ordinary fortitude as a baseline for assessing whether harm is reasonably foreseeable. The defendant takes the plaintiff as found only after the threshold of foreseeability is met. Mustapha's reaction was extreme by the ordinary-fortitude measure.

Standard authority on psychiatric injury in Canadian negligence. Distinguishes the threshold question (foreseeability in ordinary fortitude) from quantum (thin-skull). Compatible with English Page v Smith and Bourhill v Young framework.

Mustapha v Culligan of Canada Ltd, 2008 SCC 27, [2008] 2 SCR 114.

McLachlin CJ, Bastarache J, Binnie J, LeBel J, Deschamps J, Fish J, Abella J, Charron J, Rothstein J