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Reasonable Mitigation Obligations:
Involves Duty to Avoid Unnecessary Losses or Damages
Last Updated: August 22 2026
Question: How does Ontario law expect me to mitigate damages after a breach or injury claim?
Answer: In Ontario, a court generally expects a harmed person to take reasonable steps to reduce losses, because damages are limited to what naturally flows from the wrongdoing minus amounts caused by your inaction, with the doctrine explained by the Supreme Court in Southcott Estates Inc. v. Toronto Catholic District School Board, [2012] 2 S.C.R. 675. If you can’t avoid a loss, you still must act reasonably, not perfectly, and where failure to mitigate is raised, the defendant usually has the burden to prove you did not take reasonable steps and that mitigation was reasonably possible. If you’re dealing with a claim in contract, tort, employment, or construction, White Owl Legal can help you document what you did to limit harm and build a mitigation-focused response tailored to your situation in Ontario, call (289) 839-3075 for next steps.
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The Duty to Mitigate Including the Standard of Efforts to Do So
The law despises waste and the doctrine of mitigation, being the duty to mitigate, is the mechanism that imposes an obligation upon a harmed party to take reasonable steps to minimize or control avoidable losses. This principle applies in all matters of law including tort law, contract law, employment law, construction law, among various others matters.
Note: Please contact White Owl Legal by phone at: (289) 839-3075 to discuss any specific questions that you may have.
The Law
The doctrine of mitigation was explained well whereas it was said in general by the Supreme Court in Southcott Estates Inc. v. Toronto Catholic District School Board, [2012] 2 S.C.R. 675, that:
[23] This Court in Asamera Oil Corp. v. Seal Oil & General Corp., 1978 CanLII 16 (SCC), [1979] 1 S.C.R. 633, cited (at pp. 660-61) with approval the statement of Viscount Haldane L.C. in British Westinghouse Electric and Manufacturing Co. v. Underground Electric Railways Company of London, Ltd., [1912] A.C. 673, at p. 689:
The fundamental basis is thus compensation for pecuniary loss naturally flowing from the breach; but this first principle is qualified by a second, which imposes on a plaintiff the duty of taking all reasonable steps to mitigate the loss consequent on the breach, and debars him from claiming any part of the damage which is due to his neglect to take such steps.
[24] In British Columbia v. Canadian Forest Products Ltd., 2004 SCC 38 (CanLII), [2004] 2 S.C.R. 74, at para. 176, this Court explained that “[l]osses that could reasonably have been avoided are, in effect, caused by the plaintiff’s inaction, rather than the defendant’s wrong.” As a general rule, a plaintiff will not be able to recover for those losses which he could have avoided by taking reasonable steps. Where it is alleged that the plaintiff has failed to mitigate, the burden of proof is on the defendant, who needs to prove both that the plaintiff has failed to make reasonable efforts to mitigate and that mitigation was possible (Red Deer College v. Michaels, 1975 CanLII 15 (SCC), [1976] 2 S.C.R. 324; Asamera; Evans v. Teamsters Local Union No. 31, 2008 SCC 20 (CanLII), [2008] 1 S.C.R. 661, at para. 30).
[25] On the other hand, a plaintiff who does take reasonable steps to mitigate loss may recover, as damages, the costs and expenses incurred in taking those reasonable steps, provided that the costs and expenses are reasonable and were truly incurred in mitigation of damages (see P. Bates, “Mitigation of Damages: A Matter of Commercial Common Sense” (1992), 13 Advocates’ Q. 273). The valuation of damages is therefore a balancing process: as the Federal Court of Appeal stated in Redpath Industries Ltd. v. Cisco (The), 1993 CanLII 3025 (FCA), [1994] 2 F.C. 279, at p. 302: “The Court must make sure that the victim is compensated for his loss; but it must at the same time make sure that the wrongdoer is not abused.” Mitigation is a doctrine based on fairness and common sense, which seeks to do justice between the parties in the particular circumstances of the case.
Accordingly, mitigation requires the minimizing of harm. Failure to minimize the harm is a failure to mitigate and may reduce sums that a wrongdoer owes to the person harmed whereas when a failure to mitigate occurs, it is the person who was harmed and failed to reasonably minimize loss that caused some of the harm. The wrongdoer is liable only for the portion of harm caused by the wrongdoer. Examples of mitigation include, among other things, the reasonable efforts of a wrongfully dismissed employee to seek fresh employment or for the victim of an injury to attend rehabilitation rather than to allow injuries to fester while loss of income for time off work accrues needlessly.
Conclusion
The law required that a Plaintiff (or a Defendant within a counterclaim against the Plaintiff) took reasonable steps to mitigate, meaning reduce, losses. When a person failed to take reasonable steps to mitigate (reduce losses), the law will disallow claims, or the amounts within claims, that arose because of the failure to mitigate whereas the law views the losses that arise from the failure to mitigate as caused by the inaction of the victim rather than by the action of the wrongdoer. Where failure to mitigate is alleged by the Defendant, it is the Defendant who holds the duty to prove that the Plaintiff failed to mitigate and that a reasonable opportunity to mitigate was available; furthermore, the duty upon the Plaintiff is to take reasonable steps in the effort to mitigate rather than take steps to perfectly mitigate and a Defendant is unable to use the vision of hindsight to argue what the possible opportunities to mitigate were available to the Plaintiff. Again, the duty is to act reasonably without expectations of perfection.
NOTE: A significant volume of online queries featuring “lawyers near me” or “best lawyer in” typically underscores a demand for prompt, proficient legal support rather than a specific occupational designation. In Ontario, licensed paralegals are governed by the same Law Society that also regulates lawyers, granting them the authority to represent clients in specific litigation contexts. Their role hinges on advocacy, legal analysis, and procedural expertise. White Owl Legal provides legal representation within its licensed parameters, focusing on strategic positioning, evidence preparation, and compelling advocacy aimed at securing swift and favourable outcomes for clients.
