Can I sue someone on a contract I am not a party to in Ontario?

The doctrine of privity of contract means that, generally speaking, only parties to a contract can sue to enforce it or be sued under it. If you were not a party — even if the contract was made for your benefit — you normally cannot bring a claim to enforce it in Ontario.

There are recognized exceptions. A person can assign their contractual rights to a third party, who then steps into the original party's shoes. Trusts can sometimes hold contractual rights for a beneficiary. Agency relationships let an agent bind a principal. In certain construction contexts, the concept of "collateral warranty" or tort law principles can sometimes allow third-party claims.

Ontario courts have also recognized that in very limited circumstances, a third party beneficiary may have some ability to enforce a contract made specifically for their benefit, particularly where refusing to allow that claim would be unjust. The law here continues to evolve.

If you suffered a loss due to a breach of a contract that someone else made, speak with a litigation lawyer about whether any exception to privity applies to your situation, or whether another cause of action — such as negligence — might be available to you.