The phase rule and its applications

Following oral discussion and negotiation, it is customary for parties to reduce their agreements to some written form. Of the terms, conditions, and promises discussed, only those included in a writing will be enforced. This provision is because the court presumes that the parties will have put everything they agreed to in writing. The parol evidence rule will not apply when unfair and unjust decisions might result from its application. While many unjust situations can occur, they generally fall into one of five categories: incomplete, ambiguous, or erroneous agreements; void and voidable agreements; agreements based on a condition precedent; modified or rescinded agreements; or agreements involving past or usual commercial practice. In cases in which a written agreement is incomplete, oral evidence may be used to supply the missing terms. In general, the courts allow a party to a written agreement to introduce oral testimony to show that the contract is void or voidable due to a lack of mutual assent or contractual capacity ...»