COLLATERAL-CONTRACT DOCTRINE

collateral-contract doctrine.The principle that in a dispute concerning a written contract, proof of a second (usu. oral) agreement will not be excluded under the parol-evidence rule if the oral agreement is independent of and not inconsistent with the written contract, and if the information in the oral agreement would not ordinarily be ex-pected to be included in the written contract. — Also termed collateral-agreement doctrine. [Cases: Evidence  440. C.J.S. Evidence §§ 1249–1251, 1283.] [Blacks Law 8th]