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Reasonable Foreseeability:
Principles Regarding Whether an Advance Risk of Harm Arising Could Be Recognized
Last Updated: March 30 2026
Question: How does reasonable foreseeability affect whether I can claim negligence in Ontario?
Answer: In Ontario negligence claims, reasonable foreseeability is an objective test asking whether a reasonable person in the defendant’s position ought to have foreseen a real risk of the kind of harm that occurred, assessed before the incident rather than with hindsight, as discussed in 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. Hall Paralegal Services provides Ontario paralegal services to help you evaluate foreseeability and remoteness, organize evidence, and take next steps toward a potential negligence claim or defence.
Understanding Foreseeability Principles
The principle of reasonable foreseeability applies within negligence law. To simplify, reasonable foreseeability involves the awareness of risk of harm that might arise from a specific behavior. As the basics of negligence law involve the question of what a reasonably minded person would do in a given situation, it is necessary to review what a reasonably minded person might foresee as a potential risk arising from the specific behaviour that is being challenged as unreasonable.
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 explain foreseeability as pertaining to whether a person could reasonably anticipate that specific behavior might cause harm to some other person. Moreover, according to the principles established in Rankin and Mustapha, when evaluating whether harm was foreseeable, a court should approach the situation from the perspective of foresight before the incident occurred rather than in hindsight after the incident occurred.
Conclusion
Negligence law encompasses the assessment of whether an individual behaved with an unreasonable lack of care and should be deemed responsible for harm brought about by such lack of care. Within the inquiry of whether the behavior lacked due care is the question regarding whether the ensuing harm could be reasonably anticipated. If the harm was reasonably unforeseeable, then liability for the harm fails to arise.
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