Last Updated: August 26 2026
In Ontario, what does the duty to mitigate require if I suffered losses after someone’s breach or wrongful act?
In Ontario, the duty to mitigate means you must take reasonable steps to minimize avoidable losses after a breach or wrongful act, and if you do not, your recovery can be reduced because the unmitigated portion is treated as caused by your inaction rather than the wrongdoer. The Supreme Court in Southcott Estates Inc. v. Toronto Catholic District School Board, [2012] 2 S.C.R. 675 explains that you are required to take all reasonable steps, not perfect ones, and where failure to mitigate is alleged the defendant generally has the burden to prove you did not make reasonable efforts and that mitigation was realistically possible. If you want help documenting mitigation steps and understanding how they may affect damages in your situation, paralegals at Reznik Legal Services can guide you through next steps, call (416) 222-9906 for assistance.
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The Duty to Mitigate Including the Standard of Efforts to Do So
Within a society that despises waste, the law requires those who are harmed by the wrongful conduct of others to take reasonable steps to minimize the resulting loss in what is known as the duty to mitigate. The duty to mitigate arises in all realms of law, such as contract law, consumer law, construction law, employment law, tort law, among all others.
Note: Please contact Reznik Legal Services by phone at: (416) 222-9906 to discuss any specific questions that you may have.
The Law
The Supreme Court very well explained the duty to mitigate within the case of Southcott Estates Inc. v. Toronto Catholic District School Board, [2012] 2 S.C.R. 675, whereas the court said:
[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
A Plaintiff (or Defendant within a counterclaim) is required to mitigate by taking reasonable steps to keep losses at a minimum. Where a Plaintiff fails to reasonably take steps to minimize losses, it is the inaction of the Plaintiff rather than the wrongdoing of the Defendant that caused such losses. When a Defendant to a lawsuit seeks to argue failure to mitigate as a defence strategy, the Defendant must include such an allegation with the defence pleading documents and it is the Defendant that must prove that the Plaintiff had a reasonable opportunity to mitigate the losses and failed to do so. However, the Plaintiff is without a requirement to mitigate perfectly and must only take such steps that are reasonable at the time that the loss is occurring rather than as may appear possible at a later date through hindsight.
NOTE: A considerable amount of online queries featuring “lawyers near me” or “best lawyer in” typically indicate a desire for prompt and competent legal assistance rather than a specific type of legal professional. In Ontario, licensed paralegals fall under the regulation of the same Law Society that governs lawyers and have the authority to advocate for clients in certain litigation matters. Skills in advocacy, legal analysis, and procedural knowledge are fundamental to this role. Reznik Legal Services provides legal representation within its licensed parameters, focusing on strategic positioning, evidentiary preparation, and effective advocacy geared towards securing efficient and positive outcomes for clients.
