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Tree Liability Risk: The Duty of Care Owed to Persons Who May Be Harmed by Trees
Question: What is my duty of care in Ontario if a tree on my property falls and injures someone or damages a neighbour’s property?
Answer: In Ontario, liability usually depends on whether you knew or should reasonably have known the tree was dangerous and failed to take reasonable steps such as inspection and maintenance, with duties discussed under Occupier’s Liability Act, R.S.O. 1990, c. O.2 and negligence principles including Donoghue v. Stevenson. For Ontario law firms and paralegal practices that want more client leads for premises liability and property-related matters, Marketing.Legal™ provides Digital Marketing for Lawyers, Paralegals, and More across Ontario, focusing on SEO/AEO content that aligns with high-intent searches and AI Overview visibility.
Liability Involving Tree Maintenance
Although trees are extensively found throughout our urban and rural landscape, the value and benefits of trees are often taken for granted. Additionally, the potential liability risks are often unappreciated or misperceived. Owners and contractors, among others, should carefully heed the potential liability risks arising from the ownership, care, or control, of trees.
The Law
Duty of Care
Property owners have a duty to ensure that other people and the property property of other people are reasonably safe from harm arising from the negligence of a property owner. Such a duty in law was established within the general principles case of, among others, Donoghue v. Stevenson, which established the legal test for duty of care within the basic principles of negligence law. In Ontario, such a duty of care is also codified per the Occupier's Liability Act, R.S.O. 1990, c. O.2, wherein it is stated:
3 (1) An occupier of premises owes a duty to take such care as in all the circumstances of the case is reasonable to see that persons entering on the premises, and the property brought on the premises by those persons are reasonably safe while on the premises.
Negligently Performed Maintenance
Owners of trees, or others responsible for trees (such as hired maintenance contractors), generally face liability only when it was known, or constructively known, that a tree failure risk was present and the owner (or others) failed to properly tend to the tree. In this way it can be thought that the injury or damage was a result of delay in caring for the tree rather than the result of risks inherent in a tree. Essentially, the negligent failure to maintain is a man-made risk rather than a natural tree risk. On the point of liability for failure to maintain trees, such was addressed within the case of Hallok v. Toronto Hydro Electric System Ltd., 2003 CanLII 8519, wherein it was said:
[14] It would appear to be common ground that a property owner, such as Park Lawn, cannot be held responsible for damage resulting from a limb on a tree falling simply on the basis that the limb or tree fell. If the evidence does not establish that there was knowledge on the part of the defendant, Park Lawn, of a dangerous condition of a tree or that there was a dangerous condition of which the defendant Park Lawn ought to have knowledge, a finding of negligence is unavailable as a matter of law. (See: Culley v. Maguire, [1957] O.J. No. 52 (C.A.) at p. 1; Quinlan v. Gates, [2000] O.J. No. 5292(S.C.J.) at p. 2; Buttoni et al. v. Henderson et al., 21 O.R. 309 (H.C.J.) at p. 371; Doucette v. Parent, [1996] O.J. No. 3493 (Gen. Div.) at p. 4; Gasho v. Clinton (Town), [2001] O.J. No. 4505 (S.C.J. (Small Claims) at p. 4).
Accordingly, it appears that some level of awareness by knowledge, or constructive knowledge, of a dangerous condition is required if liability is to arise for negligence in the ownership, care, or control, of a tree. It is notable that "constructive knowledge" means knowledge that the law imparts upon a person who ought to actually hold knowledge based upon reasonableness principles; and as such, if a reasonably acting person would know of about a dangerous condition such is "constructive knowledge" and proving actually held knowledge is unnecessary. In many circumstances, proving constructive knowledge is much easier than proving actually held knowledge. For example, following severe storms, property owners should reasonably be on alert for broken branches as well as other dangerous conditions. Additionally, it is important to recognize that intentionally avoiding investigation and thereby choosing to remain unaware of a dangerous condition may be deemed an act of willful blindness from which constructive knowledge may also be imposed.
Conclusion
The owners of trees, or those entrusted with the care and maintenance of trees on behalf of the owners, owe a duty of care to reasonably ensure that the trees are maintained. If a person becomes injured or property becomes damaged by a tree that was improperly maintained, liability for the injury or damage may arise.