Section 7.22 Parol Evidence

• Library: Contracts 2016 Supp

A. (§7.22) Parol Evidence

To adjudicate a contract dispute, the court must first determine what the parties’ agreement is. This determination, of course, requires interpreting the contract. The first decision the court must make in interpreting a contract is what evidence the court can consider. If the contract is oral, the court considers all competent testimony about the parties’ agreement. Cf. Thompson v. St. Louis Union Trust Co., 253 S.W.2d 116 (Mo. 1952).

If the agreement is in writing, however, the court must decide whether to consider only the writing itself or to consider the writing together with other evidence. This determination involves the application of the parol-evidence rule.

The parol-evidence rule, in its simplest form, states that if the parties have expressed their final agreement in writing, the court will interpret the agreement solely from the writing and not from oral testimony; in other words, oral evidence may not vary the terms of an unambiguous, complete document. Norden v. Friedman, 756 S.W.2d 158, 163 (Mo. banc 1988). Parol evidence is a rule of substantive law, not a rule of evidence. Commerce Trust Co. v. Watts...