Integration clause is a clause in the contract that declares that the contract is a complete and final agreement between the parties. In the U.S. integration clause is not a conclusive proof that no varied or additional conditions exists with respect to the performance of a contract. Any contract which contains in it as integration clause is known as an integrated contract.
The purpose of integration clause is to prevent the parties to a contract from later claiming that the contract does not reflect their entire understanding.
Following is an example of the case law defining integration clause:
The term "integration clause" is in turn defined as "a contractual provision stating that the contract represents the parties' complete and final agreement and supersedes all informal understandings and oral agreements relating to the subject matter of the contract [Tiburzi v. DOJ, 269 F.3d 1346, 1354 (Fed. Cir. 2001)].