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Parol evidence rule

Common law rule relating to contracts

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  • 3 chapters

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The rule's origins lie in English contract law, but it has been adopted in other common law jurisdictions; however there are now some differences between application of the rule in different jurisdictions. For instance, in the US, a common misconception is that it is a rule of evidence (like the Federal Rules of Evidence), but that is not the case; whereas in England it is indeed a rule of evidence.

The supporting rationale for excluding the content of verbal agreements from written contracts is that since the contracting parties have agreed to reduce their contract to a single and final writing, extrinsic evidence of past agreements or terms should not be considered when interpreting that writing, as the parties ultimately decided to leave them out of the contract. In other words, one may not use evidence made prior to the written contract to contradict the writing.

Overview

The rule applies to statements made orally, and to other extrinsic evidence (such as written correspondence that does not form a separate contract) regarding a contract. If a contract is in writing and final to at least one term (integrated), parol or extrinsic evidence will generally be excluded. However, there are a number of exceptions to this general rule. These include partially integrated contracts, agreements with separate consideration, in order to resolve ambiguities, or to establish contract defenses.

To take an example, Carl agrees in writing to sell Betty a car for $1,000, but later, Betty argues that Carl earlier told her that she would only need to pay Carl $800. The parol evidence rule would generally prevent Betty from testifying to this alleged conversation because the testimony ($800) would directly contradict the written contract's terms ($1,000).

The precise extent of the rule varies from jurisdiction to jurisdiction. As a preliminary or threshold issue, the court may first determine if the agreement was in fact totally reduced to a written document or (in US terminology) fully "integrated". In the case of State Rail Authority of New South Wales v Heath Outdoor Pty Ltd McHugh J held that the parol evidence rule has 'no operation until it is first determined' that all the terms of the contract are in writing. This threshold question applies even in those jurisdictions that apply a very strong form of the parol evidence rule, called the "Four Corners Rule".

Beyond that, the exceptions to the parol evidence rule vary between jurisdictions. Examples of circumstances where extrinsic evidence may be admissible in different jurisdictions include:

  • To prove the parties to a contract. A written agreement to sell land signed by Mrs. Kenny at times made reference to Mr. Kenny, and the court held that oral evidence was admissible to prove that she was signing for herself and as an agent for her husband.
  • To prove a condition precedent. In Pym v Campbell (1865) 119 ER 903, Pym entered into a written contract with Campbell to sell an interest in an invention. The court allowed Campbell to include the oral terms of acknowledgement that the sale was subject to an inspection and approval by an engineer. The engineer did not approve the invention.
  • To prove that the written document is only part of the contract as in Hospital Products Ltd v United States Surgical Corporation, where the court found a written contract to be only part of an agreement. In State Rail Authority of NSW v Heath Outdoor Pty Ltd the court held that the parol evidence rule is persuasive and the evidentiary burden is on the party wishing to establish that the whole contract was not in writing.
  • To prove that an implied term of custom, trade usage, or past dealings is part of a contract even if it is not in a written agreement. In Hutton v Warren [1836] 1 M and W 466, the party wishing to add the term bore the evidentiary burden; in this case, a lease had to be read in the light of established custom.
  • To prove what is true consideration, not something added to avoid taxes.
  • To prove that the term or promise is part of a collateral contract.
  • To aid in the interpretation of existing terms.
  • To resolve ambiguity using the contra proferentem rule.
  • To show, particularly in California, that (1) in light of all the circumstances surrounding the making of the contract, that the contract is actually ambiguous (regardless of whether the contract's meaning appears unambiguous at first glance), (2) thus necessitating the use of extrinsic evidence to determine its actual meaning.
  • To disprove the validity of the contract.
  • To show that an unambiguous term in the contract is in fact a mistaken transcription of a prior valid agreement. Such a claim must be established by clear and convincing evidence, and not merely by the preponderance of the evidence.
  • To correct mistakes.
  • To show wrongful conduct such as misrepresentation, fraud, duress, unconscionability (276 N.E.2d 144, 147), or illegal purpose on the part of one or both parties.
  • To show that consideration has not actually been paid. For example, if the contract states that A has paid B $1,000 in exchange for a painting, B can introduce evidence that A had never actually conveyed the $1,000.
  • To identify the parties, especially if the parties have changed names.
  • To imply or incorporate a term of the contract.
  • To make changes in the contract after the original final contract has been agreed to. That is, oral statements can be admitted unless they are barred by a clause in the written contract.
  • In Sri Lanka, to prove the presence of attendant circumstances creating a constructive trust in relation to an ex-facie absolute notarial conveyance.

In order for evidence to fall within this rule, it must involve either (1) a written or oral communication made prior to execution of the written contract; or (2) an oral communication made contemporaneous with execution of the written contract. Evidence of a later communication will not be barred by this rule, as it is admissible to show a later modification of the contract (although it might be inadmissible for some other reason, such as the Statute of frauds). Similarly, evidence of a collateral agreement - one that would naturally and normally be included in a separate writing - will not be barred. For example, if A contracts with B to paint B's house for $1,000, B can introduce extrinsic evidence to show that A also contracted to paint B's storage shed for $100. The agreement to paint the shed would logically be in a separate document from the agreement to paint the house.

Though its name suggests that it is a procedural evidence rule, the consensus of courts and commentators is that the parol evidence rule constitutes substantive contract law.

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