Parol Evidence Rule
Contracts & Sales · Lesson 09
Parol Evidence Rule
這一課問的是：當書面合約是最終版本（integrated），能否再用之前或同時的口頭／書面陳述去更改其條款？
Actor
Act
Object
Standard
Consequence
Issue · what this lesson is really about
When a written contract is final, may a party introduce prior or contemporaneous oral or written statements to vary its terms?
這一課問的是：當書面合約是最終版本（integrated），能否再用之前或同時的口頭／書面陳述去更改其條款？
Trigger words & phrases that should flag this issue:
oral agreementprior statementmerger clausecontemporaneousside agreement
Core Terminology · 7 must-know
Tap a card to flip and reveal the meaning.
parol evidence
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Prior or contemporaneous oral or written statements not in the final writing.
口頭／外證據。
integration
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Parties' adoption of the writing as the final expression.
整合。
total integration
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Writing is the complete and exclusive statement.
完全整合。
partial integration
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Final as to terms stated; supplementary consistent terms may be added.
部分整合。
merger clause
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Clause stating writing is complete agreement — strong evidence of total integration.
整合條款。
Rule Sentence · the workhorse
The Parol Evidence Rule bars evidence of prior or contemporaneous statements that would contradict the terms of a writing the parties intended as the final expression of their agreement.
Sentence Anatomy · 5 roles, 5 colors
Every rule sentence breaks into five visual roles.
Actor 行為人a party at trial訴訟中當事人
Act 行為offering prior/contemporaneous evidence提出之前/同時證據
Object 對象an integrated writing已整合書面
Standard 法律標準integration: total vs partial完全 vs 部分整合
Consequence 後果evidence barred (or admitted)證據排除（或採納）
Casebook Snapshot · a real American case
Mitchill v. Lath
Holding. An oral collateral agreement may be admitted alongside an integrated writing only if it would naturally have been made as a separate agreement; if the alleged oral term would normally have been included in the writing, PER excludes it.
Why it matters. Side-deals naturally absorbed by ordinary contracts are barred. Closer to the writing's subject = more likely excluded.
若所稱口頭條款依常理會載入書面，則 PER 排除之。
Common Mistakes · what trips students
✗ 「Parol」指「口頭」。
✓ Parol covers prior/contemp written too.
Parol 涵蓋之前/同時之口頭與書面。
✗ PER 把所有外部證據都擋掉。
✓ Fraud, mistake, ambiguity, condition precedent are all exempt.
詐欺、錯誤、模糊、生效條件皆例外。
Mini IRAC · build the Application
Issue. May P introduce an alleged oral promise to repaint the house when the written sale agreement is fully integrated and silent on painting?
Rule. The Parol Evidence Rule bars evidence of prior or contemporaneous terms that would vary a writing intended as the final and complete agreement.
Application (model). The written house-sale agreement contained a merger clause and made no mention of painting. Because the Parol Evidence Rule bars prior or contemporaneous terms that would vary a totally integrated writing, the fact that the merger clause shows the writing was intended as the complete agreement means an oral promise that adds a new performance obligation falls within the rule's bar.
Pick the right element for each blank:
g1.
g2.
g3.
Conclusion. Therefore, the alleged oral promise is inadmissible to vary the contract.
MBE Check · multiple choice
Buyer claims seller orally promised, before signing the integrated written sale, that the property was 'free of mold.' The writing has a merger clause and is silent on mold. Buyer claims fraud. Can the oral promise come in?
Practice Drill · tap to build the rule
Drop the chips here in correct order:
Tap chips to add → tap chips in the target to remove: