Parol Evidence

MBEMax wiki article — paired with the Contracts question set on mbemax.com.

One-line summary

When the parties have a writing intended as a final expression of their agreement, the parol evidence rule bars evidence of prior or contemporaneous statements that would contradict or (if the writing is totally integrated) supplement the writing.

Mnemonic

F-I-T — is the writing Final? Is it Integrated (partially/totally)? Does the offered evidence Try to contradict/supplement?

Then run the exceptions: CMS-VICS — Condition precedent, Modification (subsequent), Separate consideration, Void/voidable attacks, Interpretation of ambiguity, Collateral agreement, Subsequent agreement.

The rule (plain-language)

A writing that is "integrated" — intended as the final expression of the parties' agreement — cannot be contradicted by evidence of prior agreements or negotiations, or contemporaneous oral agreements. If the writing is also completely integrated (intended as the complete and exclusive statement), it also cannot be supplemented.

Integration analysis

1. Final expression? Parties intended the writing to be a final statement of at least some terms.
2. Partial integration — final as to the terms it contains, but not a complete statement. Consistent additional terms are admissible.
3. Total integration — complete and exclusive statement. Even consistent additional terms are barred.
4. Merger clause — strong evidence of total integration but not conclusive (especially under UCC § 2-202 and modern Restatement, which allow looking at the "naturally omitted" test).

What parol evidence CAN do (exceptions)

• Show condition precedent to formation (not performance).
• Show no contract formed — fraud, duress, undue influence, mistake, illegality, lack of consideration.
• Interpret ambiguous terms — patent or latent ambiguity.
• Show a collateral agreement on a distinct subject, naturally omitted from the writing.
• Show subsequent modifications — the rule does not apply to post-execution events.
• Reformation for mutual mistake in transcription.
• UCC course of performance, course of dealing, usage of trade — always admissible to explain or supplement, subject to § 2-202.

NCBE loves to test

• Merger clauses ≠ automatic total integration. Most courts still look at the circumstances. A restatement "naturally omitted" test asks whether a reasonable party would include this term in the writing.
• Condition precedent trap. "No contract unless my dad approves" is admissible to show no contract formed — it's a condition precedent to existence, not a contradiction of terms.
• Fraud in the inducement vs. fraud in the factum. Both admissible; parol evidence rule does not shield a fraudulently induced or void contract.
• Course of dealing vs. express terms. Express terms control when inconsistent; course of dealing and usage of trade fill gaps and help interpret.
• Consistent additional terms. Admissible only if partial integration. Must be consistent — cannot contradict.
• Agreement to modify. Parol evidence rule has nothing to say about events after signing. No-oral-modification clauses in sale-of-goods contracts (UCC § 2-209(2)) bar oral modifications only between merchants unless the non-merchant consumer signs a separate provision.

Fast hypos

Hypo 1. Written contract for sale of house has a merger clause. Buyer wants to introduce seller's oral statement that "roof is brand new." If offered to show a warranty term contradicting "as is" merger — barred. If offered to show fraudulent misrepresentation inducing the sale — admissible exception.

Hypo 2. Contract is final and clearly integrated but silent on who pays closing costs. Buyer offers evidence that parties orally agreed seller pays. Admissible if partial integration (consistent additional term). Not if total integration plus the term is one naturally included.

Hypo 3. UCC sale. Writing says "500 widgets at $5 each." Seller wants to introduce that parties orally agreed delivery by rail only. Admissible under § 2-202(b) as consistent additional term; also admissible to show usage of trade or course of dealing.

Hypo 4. Oral statement: "This contract is not binding unless and until my partner signs." Written contract makes no mention. Admissible — condition precedent to formation.

Case anchors

• Masterson v. Sine, 436 P.2d 561 (Cal. 1968) — Traynor's functional approach to integration.
• Pacific Gas & Elec. Co. v. G.W. Thomas Drayage, 442 P.2d 641 (Cal. 1968) — extrinsic evidence admissible to show meaning even of unambiguous language (California minority view).
• Mitchill v. Lath, 247 N.Y. 377 (1928) — collateral-agreement test (three-part New York traditional test).
• Trident Center v. Connecticut General Life Insurance, 847 F.2d 564 (9th Cir. 1988) — Kozinski's critique of California rule, still applying it.

See also

• Offer and Acceptance
• Statute of Frauds
• UCC — Sales
• Modification

Sources

Restatement (Second) of Contracts §§ 209–217; UCC § 2-202; Masterson v. Sine, 436 P.2d 561 (Cal. 1968); Pacific Gas & Elec. v. G.W. Thomas Drayage, 442 P.2d 641 (Cal. 1968); Mitchill v. Lath, 247 N.Y. 377 (1928); Trident Center v. Connecticut General Life Ins., 847 F.2d 564 (9th Cir. 1988).