Can terms that were never written down be implied into a contract in Ontario?

Ontario courts recognize that contracts sometimes carry terms that the parties never expressly wrote down. Implied terms can arise in several ways. Terms implied in fact are necessary to give business efficacy to a contract — if without the term the contract makes no commercial sense, courts may read it in, provided it is so obvious it goes without saying and does not contradict the express terms.

Terms implied in law apply automatically to certain types of contracts regardless of what the parties agreed. For example, a term of reasonable care may be implied in contracts for services, and certain warranties can be implied into sales of goods under the Sale of Goods Act.

Ontario courts have also developed the principle of good faith in contractual performance — parties must not act in ways that are clearly dishonest or that undermine the other side's right to receive the benefit of the bargain. This does not impose a general duty to put the other party's interests first, but it can constrain opportunistic conduct.

Courts are cautious about implying terms and will not do so simply because one party would have liked the term to be there. The bar is genuine necessity or established legal implication, not mere reasonableness or fairness.