United States In order for the rule to be effective, the contract in question must first be a final integrated writing; it must, in the judgment of the court, be the final agreement between the parties (as opposed to a mere draft, for example). A final agreement is either a partial or complete integration, provided that it has an agreement on its face indicating its finality. If it contains some, but not all, of the terms as to which the parties have agreed then it is a partial integration. This means that the writing was a final agreement between the parties (and not mere preliminary negotiations) as to some terms, but not as to others. On the other hand, if the writing were to contain all of the terms as to which the parties agreed, then it would be a complete integration. One way to ensure that the contract will be found to be a final and complete integration is through the inclusion of a
merger clause, which recites that the contract is, in fact, the whole agreement between the parties. However, many modern cases have found merger clauses to be only a
rebuttable presumption. The importance of the distinction between partial and complete integrations is relevant to what evidence is excluded under the parol evidence rule. For both complete and partial integrations, evidence contradicting the writing is excluded under the parol evidence rule. However, for a partial integration, terms that supplement the writing are admissible. To put it mildly, this can be an extremely subtle (and subjective) distinction. To put it simply, (1) If the parties intend a complete integration of the contract terms, no parol evidence within the scope of agreement is permitted. (2) If the parties intended a partial integrated agreement, no parol evidence that contradicts anything integrated is permitted. And (3), if the parol evidence is collateral, meaning it regards a different agreement, and does not contradict the integrated terms, and are not terms any reasonable person would always naturally integrate, then the rule does not apply and the evidence is admissible. In a minority of U.S. states, (Florida, Colorado, and Wisconsin), the parol evidence rule is extremely strong and extrinsic evidence is always barred from being used to interpret a contract. This is called the
Four Corners Rule, and it is traditional/old. In a Four Corners Rule jurisdiction, there are two basic rules. First, the court will never allow parol evidence if the parties intended a full and completely integrated agreement, and second, the court will only turn to parol evidence if a contract term is wholly ambiguous. The policy is to prevent lying, to protect against doubtful veracity, to enable parties to rely dearly on written contracts, and for judicial efficiency. In most jurisdictions there are numerous exceptions to this rule, and in those jurisdictions, extrinsic evidence may be admitted for various purposes. This is called the Admission Rule. It favors liberalizing the admission of evidence to determine if the contract was fully integrated and to determine if the parol evidence is relevant. In these jurisdictions, such as California, one can bring in parol evidence even if the contract is unambiguous on its face, if the parol evidence creates ambiguity. The third and final admissibility rule is that under the UCC § 2-202: Parol evidence cannot contradict a writing intended to be the "final expression" of the agreement integrated but may be explained or supplemented by (a) a course of dealing/usage of trade/ course of performance, and by (b) evidence of consistent additional terms unless the writing was also intended to be a complete and exclusive statement of the terms of the agreement. Additional information on the parol evidence rule may be found in Restatement (Second) of Contracts § 213.
Australia In New South Wales, if an entire agreement clause, However there are two exceptions that could overcome the parol evidence rule that extrinsic evidence is admissible: Exception 1: the contract is an oral contract or partly written. Exception 2: parties may have entered into a collateral contract, Also, a narrow view of admissibility of extrinsic evidence has been taken, where evidence of surrounding circumstances is only admissible to resolve patent ambiguity, latent ambiguity, and inherent ambiguity in the meaning of the words of a contract. The High Court in
Electricity Generation Corporation v Woodside Energy Ltd took a different approach to interpreting commercial contracts, considering the "language used by the parties, the surrounding circumstances known to them and the commercial purpose or objects to be secured by the contract" at the "genesis of the transaction". This necessarily implies consideration of surrounding circumstances and indicates a broader approach may be adopted by the court in the future. The latest view is the narrow view which was described in
Mount Bruce Mining Pty Limited v Wright Prospecting Pty Limited. See
L G Throne v Thomas Borthwick where the dissent of
Herron J has been subsequently adopted.
South Africa In
South Africa the
Supreme Court of Appeal, beginning with the landmark ruling in
KPMG Chartered Accountants (SA) v Securefin Ltd, redefined the rules relating to the admissibility of evidence that may be used in the interpretation of
contracts in
South Africa and in
Dexgroup (Pty) Ltd v Trustco Group International (Pty) Ltd the Supreme Court of Appeal gave further clarity on these rules. The starting point is the language of the document and the parol evidence rule prevents evidence to add to, detract from or modify the words contained in the document. However, evidence to prove the meaning of the words, expressions, sentences and terms that constitute the contract, is admissible from the outset irrespective of whether there is any uncertainty or ambiguity in the text – as long as the evidence concerned points to a meaning which the text can reasonably have and the evidence is relevant to prove the common intention of the parties. ==See also==