What do I need to prove to win a breach of contract case in Ontario?
In Ontario civil litigation, the standard of proof is the balance of probabilities — you must show that it is more likely than not that your version of events is true. This is a lower threshold than the criminal standard of beyond a reasonable doubt.
To establish a breach-of-contract claim, you must prove four things: (1) a valid contract existed, requiring offer, acceptance, consideration, certainty of terms, and the intention to be legally bound; (2) you performed your own obligations under the contract (or had a valid excuse for not doing so); (3) the defendant failed to perform one or more of their contractual obligations; and (4) you suffered a loss as a result of that failure.
Gathering evidence for each element matters. The written contract itself, correspondence, invoices, payment records, delivery records, and witness evidence from people who observed the parties' dealings all help establish these facts.
If the defendant raises defences — frustration, misrepresentation, unconscionability, waiver — they bear the burden of proving those defences. The overall burden of proving the claim, however, stays with you throughout.
A litigation lawyer can assess the strength of each element of your claim and identify where evidence gaps exist before you commit to the cost and time of litigation.
Key takeaways
- Civil claims are proven on the balance of probabilities — more likely than not.
- Prove: a valid contract, your own performance, the defendant's breach, and your resulting loss.
- Documentary evidence — contract, emails, invoices — is central to contract claims.
- Defendants bear the burden of proving any affirmative defences they raise.