What is the Parol Evidence Rule?

A key part of understanding why an integration clause is important is understanding what the parol evidence rule is.

What is the Parol Evidence Rule?

Generally speaking, the parol evidence rule bars (or keeps out) extrinsic evidence of a prior or contemporaneous agreement.  In English, this means that once parties to a contract sign and agree to the terms of the contract, the parol evidence rule will keep the parties to the agreement from trying to submit prior oral or written statements to modify or contradict terms or clauses in the contract.

Take the example we posted in our previous blog post on integration clauses.  In that example, Party B agreed to buy “industry standard gears” for a specified sum, but in Party B’s conversations with Party A, they discussed “type-1” gears.  Thus, when Party A delivers “type 3” gears, Party B will go to court and attempt to submit parol evidence that the agreement was for 100 “type-1” gears.

As we noted in prior posts, the parol evidence rule is codified in California Code of Civil Procedure section 1856, which states that the “[t]erms set forth in a writing intended by the parties as a final expression of their agreement with respect to the terms included therein may not be contradicted by evidence of a prior agreement or of a contemporaneous oral agreement.”   Likewise,  California Civil Code section 1625 states that “[t]he execution of a contract in writing, whether the law requires it to be written or not, supersedes all the negotiations or stipulations concerning its matter which preceded or accompanied the execution of the instrument.”

As we explained in our prior blog post, most contracts have an integration clause, which will be used  to determine whether the contract is “a final expression” of the parties’ agreement.  Assuming that is the case, a party will have to show that an exception to the parol evidence rule applies.

What are the Exceptions to the Parol Evidence Rule?

Generally, the parol evidence rule will not allow a party to a written agreement to submit prior inconsistent statements (written or oral), although there are exceptions.  The following general circumstances are exceptions to the parol evidence rule:

• Incomplete writings
• Collateral or independent agreements
• Subsequent agreements
• Ambiguity or uncertainty in instrument
• Illegality or bad faith
• Fraud
• Mistake
• Lack of consideration

If one of these exceptions applies a party may then be able to submit evidence that was prior to or contemporaneous with the written contract in order to explain or contradict the terms of the deal.