In addition to the guiding principles of contract interpretation presented by Lord Hoffmann in the CSI (see practical note: interpretation of the contract – guiding principles), other rules have been developed to assist in the interpretation of the contract. The starting point is the Parol evidenti, which limits the admissibility of extrinsic evidence as a means of completing, amending or refuting a written agreement. More information can be found in the practical notes: interpretation of the treaty – admissibility of the surrounding documents and interpretation of the treaty – admissibility of pre-contract negotiations and declarations. In general, the Parol rule of evidence prevents the introduction of evidence of prior or simultaneous negotiations and agreements that contradict, alter or alter the contractual terms of a written contract if the written contract is to serve as a complete and definitive expression of the parties` agreement. A merger clause reinforces the presumption that the written document is complete and definitive, explicitly specifying that the written document is the definitive and complete expression of the parties` agreement. Although the parties later agreed that they had an interview that established an “incidental agreement” that was not included in the meeting. B the initial written contract and that the ancillary agreement contradicts the written contract (for example. B by changing the delivery date or purchase price), the additional or other conditions contained in the ancillary agreement cannot be applied by the court if there is a merger clause in the written contract. To determine when a contract has been entered into, the courts will review the circumstances to see if the parties wanted the written agreement to be a final and complete agreement. The provisions of the treaty are part of that. The Parol rule of evidence is a matter of external evidence and contracts. When a contract is “integrated” and concluded, it will be difficult for a party to put in place external evidence of other agreements or commitments made. However, there are many exceptions that sometimes allow for the introduction of external evidence.
The reason for this is that, since the parties have reduced their consent to a single and definitive handwriting, the interpretation of this letter should not take into account extrinsic evidence of prior agreements or conditions, since the parties ultimately decided to withdraw them from the contract.