Last Updated: August 22 2026
In Ontario, what does the duty to mitigate mean if I suffered losses after someone else’s wrongful conduct?
In Ontario, the duty to mitigate requires a harmed person to take reasonable steps to reduce the losses flowing from another party’s wrongful conduct; if you do not act reasonably, the other side may argue you caused part of your own damages through inaction, which can reduce what you recover and can also include allowing you to recover reasonable mitigation costs you truly incur. Courts commonly cite that this is a fairness-based rule that does not require perfection, and the burden is on the defendant to prove a failure to take reasonable mitigation steps and that mitigation was realistically possible. If you are dealing with a claim or possible lawsuit and need help evaluating mitigation steps for your situation, Caruso Legal Services can assist as a paralegal service across Ontario; call (289) 271-0488 to discuss your next steps.
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The Duty to Mitigate Including the Standard of Efforts to Do So
In a conscientious society, reasonably minded persons prefer to avoid waste; and accordingly, the law imposes the principle of mitigation, being a duty to mitigate, upon a harmed party. The duty to mitigate imposes a requirement upon a harmed person to act reasonably by taking steps that reduce or control losses and applies to all areas of law.
Note: Please contact Caruso Legal Services by phone at: (289) 271-0488 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, the duty to mitigate requires a harmed person to minimize the harm suffered. Failure to minimize the harm may, and likely will, reduce the sum that the wrongdoer will owe the harmed person in a determination of liability at a court Trial. As was explained above by the Supreme Court in the Southcott Estates case, where a failure to mitigate occurs, it is the failure of the Plaintiff to act reasonably to minimize the loss that caused a portion 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. 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 inquiries featuring “lawyers near me” or “best lawyer in” typically indicate a pressing requirement for competent legal assistance, rather than a precise designation. In Ontario, licensed paralegals are overseen by the same Law Society that governs lawyers and have the authority to assist clients in specified litigation matters. Advocacy, legal interpretation, and procedural expertise are fundamental to this role. Caruso Legal Services provides legal representation within its licensed framework, focusing on strategic planning, evidence preparation, and compelling advocacy aimed at securing effective and beneficial outcomes for clients.
