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Reasonable Foreseeability:
Principles Regarding Whether an Advance Risk of Harm Arising Could Be Recognized
Last Updated: August 23 2026
Question: In Ontario negligence claims, how do courts decide if harm was reasonably foreseeable?
Answer: Vescio Legal Services can help you understand how reasonable foreseeability works in Ontario negligence cases, using an objective test that asks whether a reasonably minded person in the defendant’s position ought to have foreseen the harm before it occurred, not based on hindsight. Courts look for a “real risk” that would not be brushed aside as far-fetched, and they also consider remoteness to decide whether the harm is too unrelated to hold the defendant fairly liable. If you want paralegal guidance on how foreseeability may affect your claim or defence, call (416) 400-8255 to book a free 15-minute consultation.
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Understanding Foreseeability Principles
Negligence law includes the principle of reasonable foreseeability. Reasonable foreseeability involves the question of whether a reasonable person could envision the risk of harm arising from the specific conduct in question. As a fundamental component of negligence law principles requires an analysis of what a reasonable person would do or avoid doing, analyzing what a reasonable person would view as risky becomes necessary within a negligence liability discussion.
The Law
In the cases of Rankin (Rankin’s Garage & Sales) v. J.J., [2018] 1 S.C.R. 587, as well as Mustapha v. Culligan of Canada Ltd., [2008] 2 S.C.R. 114, the Supreme Court explained the concept of reasonable foreseeability and remoteness whereas it was said:
[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.”
The Rankin and Mustapha cases describe the foreseeability question as relating to whether an individual could sensibly foresee that certain behavior might culminate in the occurrence of harm to another person. Furthermore, in line with the Rankin and Mustapha case decisions, when analyzing whether harm was foreseeable, a court is required to consider the event from the perspective of foresight as opposed to looking back with hindsight after harm has actually occurred.
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 rationally unforeseeable, then negligence failed to occur.
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