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Reasonable Foreseeability:
Principles Regarding Whether an Advance Risk of Harm Arising Could Be Recognized
Last Updated: August 23 2026
Question: How does reasonable foreseeability affect negligence liability in Ontario?
Answer: Reasonable foreseeability in Ontario negligence asks whether a person in the defendant’s position ought to have anticipated a real risk of harm before the incident (not after it happened), and remoteness limits liability to harm that is not too unrelated to the wrongful conduct, as explained by Rankin (Rankin’s Garage & Sales) v. J.J., [2018] 1 S.C.R. 587 and Mustapha v. Culligan of Canada Ltd., [2008] 2 S.C.R. 114 If the alleged harm was not reasonably foreseeable, liability for negligence can fail. For help applying these foreseeability principles to your specific facts, a paralegal from Forseti Legal Services can review your situation and next steps in plain language, call (705) 806-7577 to book a consultation.
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Understanding Foreseeability Principles
In negligence law, the principle of reasonable foreseeability applies. Simply put, reasonable foreseeability means the common sense thinking ahead and understanding of what might happen as a result of certain conduct. As the core definition of negligence involves the failure to do, or avoid doing, what a reasonably acting person who do, or would avoid doing, an understanding of what a reasonably acting person might perceive as posing a risk is required.
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The Law
As per the cases of Rankin (Rankin’s Garage & Sales) v. J.J., [2018] 1 S.C.R. 587, and Mustapha v. Culligan of Canada Ltd., [2008] 2 S.C.R. 114, the Supreme Court explained reasonable foreseeability and remoteness principles by stating:
[53] Whether or not something is “reasonably foreseeable” is an objective test. The analysis is focussed on whether someone in the defendant’s position ought reasonably to have foreseen the harm rather than whether the specific defendant did. Courts should be vigilant in ensuring that the analysis is not clouded by the fact that the event in question actually did occur. The question is properly focussed on whether foreseeability was present prior to the incident occurring and not with the aid of 20/20 hindsight: L. N. Klar and C.S.G. Jefferies, Tort Law (6th ed. 2017), at p. 212.
[12] The remoteness inquiry asks whether “the harm [is] too unrelated to the wrongful conduct to hold the defendant fairly liable” (Linden and Feldthusen, at p. 360). Since The Wagon Mound (No. 1), the principle has been that “it is the foresight of the reasonable man which alone can determine responsibility” (Overseas Tankship (U.K.) Ltd. v. Morts Dock & Engineering Co., [1961] A.C. 388 (P.C.), at p. 424).
[13] Much has been written on how probable or likely a harm needs to be in order to be considered reasonably foreseeable. The parties raise the question of whether a reasonably foreseeable harm is one whose occurrence is probable or merely possible. In my view, these terms are misleading. Any harm which has actually occurred is “possible”; it is therefore clear that possibility alone does not provide a meaningful standard for the application of reasonable foreseeability. The degree of probability that would satisfy the reasonable foreseeability requirement was described in The Wagon Mound (No. 2) as a “real risk”, i.e. “one which would occur to the mind of a reasonable man in the position of the defendan[t] . . . and which he would not brush aside as far-fetched” (Overseas Tankship (U.K.) Ltd. v. Miller Steamship Co. Pty., [1967] A.C. 617 (P.C.), at p. 643).
[14] The remoteness inquiry depends not only upon the degree of probability required to meet the reasonable foreseeability requirement, but also upon whether or not the plaintiff is considered objectively or subjectively. One of the questions that arose in this case was whether, in judging whether the personal injury was foreseeable, one looks at a person of “ordinary fortitude” or at a particular plaintiff with his or her particular vulnerabilities. This question may be acute in claims for mental injury, since there is a wide variation in how particular people respond to particular stressors. The law has consistently held — albeit within the duty of care analysis — that the question is what a person of ordinary fortitude would suffer: see White v. Chief Constable of South Yorkshire Police, [1998] 3 W.L.R. 1509 (H.L.); Devji v. Burnaby (District) (1999), 180 D.L.R. (4th) 205, 1999 BCCA 599; Vanek. As stated in White, at p. 1512: “The law expects reasonable fortitude and robustness of its citizens and will not impose liability for the exceptional frailty of certain individuals.”
As per Rankin and Mustapha, foreseeability involves the question of whether a person could rationally anticipate that certain actions might bring about harm to another person. Additionally, per Rankin and Mustapha, when reviewing whether harm was foreseeable a court must consider the incident from the perspective of foresight rather than in hindsight.
Conclusion
Negligence law involves the scrutiny of whether an individual acted without proper care and should be held accountable for the harm caused to another person. A component of the scrutiny into whether actions were without proper care involves the inquiry into whether the harm caused could be rationally seen as a possibility. If the harm was reasonably unforeseeable, then liability for the harm fails to arise.
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