Parol Evidence and Washington Contracts

Updated: Sep 11

What is parol evidence in Vancouver, WA, and how does it impact the agreement you've put in writing?

What is parol evidence?

If you read our article on the statue of frauds in WA, you know that some contracts must be in writing before a court will enforce them. You can have a validly enforceable oral contract as long as it is not a type of contract that falls under the statute of frauds. But when a contract is put in writing, whether the statute of frauds requires it or not, there are certain rules that apply. And one of those is the parol evidence rule.


The parol evidence rule states that a written agreement "may not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement" RCW 62A.2-202

In other words, if it's on your mind, make sure it ends up in the writing; otherwise you'll be left only with what is ascertainable by reading the final document.

"...if it's on your mind, make sure it ends up in the writing...."

Can I ever bring up parol evidence in Washington?

Yes. Contracts for the sale of goods, by their very nature, contain terms that are ambiguous and unclear, and may even be missing some terms. In this case, parol evidence may be necessary because looking at the document alone doesn't tell us everything we need to know, and using the evidence explains the document without contradicting it.

"...contracts for the sale of goods, by their very nature, contain terms that are ambiguous and unclear, and may even be missing some terms."

Example: WA Fishmongers, LLC has a contract to purchase 50 pounds of trout every week from WA Seafood Growers, Inc. The written agreement states that WA Seafood Growers must deliver 50 pounds of trout that are "market size." If the contract is for the sale goods, as it is here, the law finds that a contract was formed even when a term is unclear or ambiguous. (That is not the case for service contracts.) Both merchants, with their experience in the business, know "market size" to mean 12-16 ounces in their industry. Thus their mutual intent was to deal with trout of 12-16 ounces, but that is not clear from the written agreement. Therefore, we would need extrinsic parol evidence to explain an ambiguous term in the contract. The Washington Revised Commercial Code, 62A.2-202, states that parol evidence may be used to explain or supplement the terms of a goods contract, using the following forms of parol evidence:

  • Course of performance: This refers to how parties have performed the contract up to the point of the dispute. If WA Fishmongers had accepted 12-16 ounce trout up until a dispute with WA Seafood Growers, they could not argue they believed "market size" meant 20-24 ounces when they go to court.

  • Course of dealings: This refers to contracts the parties have had with each other in the past. It works like course of performance evidence, except you look at how the parties behaved with different contracts in the past, not the current contract in dispute.

  • Trade usage: This refers to evidence of what is customary in the trade, such as the seafood industry in WA. In other words, is there evidence that anyone in the WA seafood industry would know the industry standard for "market size" trout always means 12-16 ounces?

Bottom line: To be on the safe side, always reduce the terms of your WA contract into a written agreement which encompasses every concern of your business.

If you have more questions about parol evidence in Vancouver, Washington, or about contracts in general, please contact In-house | On-site to speak with a Vancouver WA lawyer.

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