What does an 'entire agreement' clause do in an Ontario contract?

An entire agreement clause (sometimes called an integration clause) states that the written contract represents the complete agreement between the parties and supersedes all prior discussions, promises, and representations. Its purpose is to prevent one side from later claiming that something said during negotiations — but not included in the final document — is part of the deal.

In Ontario, courts generally respect entire agreement clauses in commercial contracts between sophisticated parties. If you signed a contract with one and now want to rely on a pre-contract promise your counterparty made, you will have a difficult time unless the clause was fraudulently induced or was itself part of a misrepresentation.

The practical lesson: read the entire agreement clause carefully before signing. If there were specific verbal promises or representations that induced you to sign — a promise about delivery timelines, pricing, or performance standards — make sure those are written into the contract itself. Once you sign with an entire agreement clause, what is in the document is almost certainly all you will be able to enforce.