A signed deal holds value only when you can enforce it. When someone abandons their obligations, whether a customer stops paying on a delivered order, a supplier fails to ship goods you have already resold, or a partner walks away from a joint venture midway, a breach of contract can freeze receivables, halt a project mid-stream, and force you to cover costs you never planned for.
A broken contract is a setback, not a dead end. The good news is that the law gives you concrete ways to recover what you lost, provided you move deliberately and build your claim from the start. In Ontario, the law of contract is derived mainly from the common law, determined over the centuries by court decisions. Similar principles apply through much of the English-speaking world.
This guide explains how courts calculate damages under the expectation measure. Alternately, sometimes specific performance or an injunction makes more sense than a cash award. We will also explain what your duty to mitigate demands, and how to structure your claim so a judgment turns into money actually collected. Enforced properly, a contract protects exactly what you signed it to protect.
What Counts as a Breach of Contract in Ontario
A breach happens when one party fails, without lawful excuse, to perform an obligation the contract requires. That obligation can come from a signed document, an exchange of emails, or even an oral agreement, because Ontario law enforces contracts in many forms. The practical question is rarely whether a promise existed. Instead, it is whether the promise was broken and what that breach cost you.
Not every breach carries the same weight, though. Ontario contract law distinguishes a minor breach, which entitles you to damages but not termination, from a fundamental breach that goes to the root of the deal and lets you walk away. For example, a supplier who delivers late once has likely committed a minor breach, whereas one who never delivers at all has struck at the heart of the bargain. A term that looks minor on paper can also prove fundamental in practice, depending on how central it was to the deal, so knowing which category applies shapes every decision that follows.
A valid claim also requires a real loss. If the other side broke a term but you suffered no measurable harm, a court may award only nominal damages.
Before you sue, tie the breach to a specific dollar figure your records can prove, be it the invoice for replacement goods, the profit lost on a sale that fell through, the cost of fixing defective work, or the money you spent while relying on the promise. Ontario law also expects reasonable mitigation. This means that, where feasible, you should take alternative steps to reduce your loss. Any loss you could have avoided by sourcing elsewhere or reletting without delay may be trimmed from your award. A claim grounded in concrete numbers, backed by contracts, invoices, receipts, and correspondence, carries far more weight than one resting on general grievance, whether before a judge or in settlement negotiations.
Anticipatory Breach: When They Signal They Will Not Perform
Anticipatory breach happens when the other side tells you, before their performance is due, that they will not carry out the contract. The repudiation can be express, such as a clear statement that they will not deliver or pay, or it can be implied by conduct that makes performance impossible, such as selling to a third party the very asset they promised you. Under Ontario law the signal must be clear and unequivocal. A vague grumble or a request to renegotiate is not repudiation, and treating it as such can put you in breach instead.
Once a genuine repudiation exists, you must make a decision. You can accept the repudiation, treat the contract as at an end, and sue immediately for damages, or you can affirm it, hold the other party to performance, and wait for the due date. You must communicate your decision, and once made it is generally binding, so this is the moment for advice rather than instinct.
The choice affects your damages. If you accept the repudiation, your duty to mitigate kicks in promptly, and a court will measure your loss from that point. Affirming the contract instead keeps your rights under it, but you also take on the risk that circumstances shift against you. For that reason, businesses often document the breach carefully before deciding how to respond.
How Courts Measure Damages for Breach of Contract in Ontario
The default remedy is money, and the goal is straightforward: to put you in the position you would have occupied had the contract been performed. Lawyers call these expectation damages, and they form the backbone of most breach of contract claims in Ontario. In practice, that means recovering lost profits, the extra cost of a replacement supplier, or the value of goods you paid for but never received.
Recovery is not unlimited, however. The classic rule from Hadley v. Baxendale (1854), still applied by Ontario courts today, limits damages to losses that are not too remote. Under that test, you can recover losses that flow naturally from the breach in the usual course of things, plus losses that both parties would reasonably have contemplated when they made the deal.
The second branch matters most for unusual or high-value losses. A late delivery that costs you a specific lucrative contract, for instance, becomes far more recoverable where you told the other side about that risk up front. The parties must reasonably contemplate the loss, so communicating your special circumstances at signing can dramatically expand what you can claim later.
The Duty to Mitigate Your Losses
Ontario law will not let you sit back and let damages pile up. Once a breach occurs, you must take reasonable steps to reduce your loss, a principle known as the duty to mitigate. A supplier default generally obliges you to source a reasonable replacement rather than simply shutting down and billing the whole loss to the breaching party.
The duty is not a heavy one, and the burden sits with the defendant to prove you failed it. In fact, the Court of Appeal has confirmed that a defendant must show both that you failed to take reasonable steps and that those steps would actually have reduced the loss. Nonetheless, documenting your mitigation efforts protects your claim and undercuts a common line of defence.
When the Contract Sets the Damages in Advance
Many commercial contracts try to fix the consequences of a breach ahead of time through a liquidated damages clause. Such a clause states a set amount payable if a party defaults, which spares everyone the difficulty of proving loss after the fact. Where the amount reflects a genuine pre-estimate of the likely loss, Ontario courts will usually enforce it.
There is a limit, though. A fixed sum that works as a penalty to punish rather than to compensate may fail entirely, since courts decline to enforce penalties. Sophisticated parties who negotiate a clear limitation of liability clause will generally be held to their bargain. Reviewing these clauses before you sign, and again before you sue, therefore pays real dividends.
The Duty of Honest Performance
Ontario contract law changed meaningfully in the last decade. In Bhasin v. Hrynew, 2014 SCC 71, [2014] 3 S.C.R. 494, the Supreme Court of Canada recognized a general organizing principle of good faith and a specific duty of honest performance that applies to every contract. As Justice Cromwell put it, “[P]arties must not lie or otherwise knowingly mislead each other” about matters directly linked to performing the contract, at paragraph 73.
The Court did not leave this as an abstract idea. It awarded the wronged dealer damages of $87,000, measured by the business value he lost because the other side performed dishonestly. This duty cannot be contracted out of, so even an airtight termination clause will not shield a party who exercises it through lies or deception.
Silence and Half-Truths Can Breach the Duty
The Supreme Court went further in C.M. Callow Inc. v. Zollinger, 2020 SCC 45, [2020] 3 S.C.R. 908. There, a property manager actively misled a contractor into believing a maintenance contract would continue, then terminated it. The Court held, at paragraph 37, that the deception was directly linked to the contract because the party exercised its termination right dishonestly.
Callow expanded the practical reach of the duty in a way business owners should note. Knowingly misleading a counterparty can include half-truths, omissions, and even silence that allows a false impression to continue. Consequently, if your counterparty strings you along while quietly planning to exit, that conduct may itself ground a breach of contract claim.
For business owners, these two decisions carry a clear message. The law now expects a baseline of honesty in how you exercise contractual rights, and a counterparty who betrays that expectation exposes itself to liability. This shift rewards parties who keep clear written records of what they were told and when, since a documented pattern of misleading statements can turn an ordinary dispute into a strong claim.
Remedies Beyond a Simple Payout
Damages are the usual remedy, yet they are not the only one. An Ontario court may grant equitable relief in situations where money cannot adequately compensate you. The two most important forms are specific performance, which forces the other side to actually perform; and an injunction, which restrains them from breaching a negative covenant such as a non-compete.
A Recent Example: Blocking a Bad-Faith Exit
Courts reserve these remedies for cases where damages fall short. A recent decision shows the principle in action. In CSN Collision (Canada) Inc. v. Lift Auto Group Ltd., 2026 ONSC 1396 (CanLII), the Superior Court granted a permanent injunction to stop a partner from abandoning a long-term royalty network and rebranding its shops, even though the departing party offered to pay whatever damages it caused.
The court rejected the argument that a payout would suffice, because the losses were too complex and uncertain to quantify reliably over a nineteen-year remaining term. This reasoning targets the idea of efficient breach, where a party treats damages as simply the price of walking away. Where the harm resists calculation, an Ontario court may refuse to let a party buy its way out and will order performance instead.
Proving Lost Profits Is Where Cases Are Won or Lost
A right to damages means little if you cannot prove the number. Ontario courts require more than a plausible story about what you might have earned, and vague assertions rarely persuade a judge. In the CSN Collision case, the court found the plaintiff’s economic evidence too general to be useful, which shows how even a strong claim can stumble on proof.
The practical lesson is to build your damages case with real evidence: historical financial statements, comparable transactions, expert valuation, and clear records tying the breach to specific losses. The burden rests on you, so investing early in credible quantification often determines how much you recover. Solid numbers also strengthen your hand in settlement talks long before any trial.
What to Do Next and When to Call a Lawyer
If you are facing a breach, move quickly and methodically rather than reacting in anger. Start by gathering the paper trail: the contract, amendments, invoices, delivery records, and every email or text touching performance. Damages demand proof, and this documentation often decides how much you ultimately recover.
Next, watch the clock. Under the Limitations Act, 2002 (SO 2002, c 24, Sch B), most breach of contract claims in Ontario carry a two-year deadline that runs from the day you discovered, or reasonably should have discovered, the claim. Missing it can extinguish an otherwise strong case, so calendar the date early and treat it as firm.
You should call a litigator once the amounts at stake are meaningful, the other side disputes liability, or the contract involves specific performance or an injunction. A lawyer can assess whether summary judgment offers a faster route, quantify your damages credibly, and often resolve the matter through a demand letter or negotiation. In many cases, early advice recovers more money and avoids the cost of a full trial.
Interest and Legal Costs Add to the Picture
A damages award rarely stands alone. Ontario courts routinely add prejudgment interest to compensate you for being kept out of your money, which increases the value of a timely claim.
The successful party also usually recovers a portion of its legal costs from the loser. In the CSN Collision matter, for example, the court awarded the winning party $185,000 in costs on top of the injunction. These add-ons reward parties who pursue meritorious claims efficiently and penalize those who force needless litigation.
Conclusion
A breach of contract in Ontario does not have to sink your business, because the law offers real and flexible tools to recover what you are owed. From expectation damages and the duty of honest performance to injunctions that stop a bad-faith exit, your options depend on the facts, your records, and how fast you act. If a broken agreement is costing your business, the litigation team at Cowan can review your contract, assess your damages, and map out the strongest path to recovery. Reach out to discuss your situation in confidence.
