For example, if a buyer agrees to buy a car from a car dealership and the dealer has many identical models, it can be shown that a particular vehicle has been sold (identified by its identification number). Some have argued that Parol`s evidence should be admissible because it may reflect ideas that have been agreed upon by both parties but which, for some reason, are excluded from the contract (perhaps with ill intent on the part of one party). Some courts have found that, even with the Parol rule of law, they allow to be eligible for negotiations before as evidence, if the evidence satisfies 3 components: The complainants signed the contract without reading and soon insolvent. In the litigation, the complainants claimed that the credit union had acted fraudulently to induce them to restructure the debt contract. The complainants sought to provide external evidence that the vice-president of the credit union met with them two weeks before the contract was signed and promised that the association would extend the loan by two years, not three months. These alleged undertakings were directly contrary to the written contract, which provided for an indulgence of only three months, not two years.  The Parol evidention rule must receive “the four corners” of the contract: it generally prohibits the introduction of oral or written bargaining elements that have not been included in the written contract, subject to a series of exceptions. The Parol rule of evidence has been the subject of much discussion among legal experts. Two well-known scholars, Corbin J.A. and Williston J.A., expressed differing views on this issue: the reason for support is that, since the parties reduced their consent to a single and definitive handwriting, extrinsic evidence of past agreements or conditions should not be taken into account when interpreting this letter, since the parties had decided to remove it from the treaty. In other words, evidence made before the written contract should not be used to contradict the letter. There are a few exceptions to the parol rule of evidence. The evidence of the following is permissible: identification is an important exception to the rule.
Evidence may be introduced to identify a party that has changed its name or could be confused with another person. Evidence may also be provided to identify the purpose of the contract. To put it simply: (1) If the parties are considering a full integration of the terms of the contract, no Parol evidence is allowed under the agreement. (2) If the parties are considering a partially integrated agreement, it is not permissible to obtain evidence from Parol that opposes something integrated. And (3) if the Parol evidence is a guarantee, that is, it relates to another agreement and is not in contradiction with the integrated terms and are not terms that a reasonable person would always naturally incorporate, then the rule does not apply and the evidence is admissible.