An entire agreement or integration clause states that the written contract is the complete agreement and supersedes prior discussions. Its purpose is to prevent a party arguing that something said in negotiation formed part of the deal.

Against contract claims it generally works. The parol evidence rule bars extrinsic evidence to contradict or add to a fully integrated written agreement, and the clause is strong evidence of integration.

Against fraud claims it works less reliably. Many jurisdictions will not allow a boilerplate integration clause to defeat a claim that the contract was induced by a misrepresentation, on the reasoning that a party should not be able to contract out of responsibility for its own fraud. Where such protection is achievable at all, it usually requires a specific non-reliance clause — stating that the party has not relied on any representation outside the document, and sometimes identifying the subject matter.

Practical consequences. For a buyer, an aggressive non-reliance clause can eliminate recourse for statements made during diligence, so anything relied on should be moved into the representations. For a seller, a general integration clause alone is thinner protection than it looks.

Ambiguity is the other limit: where a term is ambiguous, extrinsic evidence of context is generally admissible to interpret it regardless of the clause.