What is the "parol evidence rule"?

The parol evidence rule is a legal doctrine in contract law that prevents the parties involved in a written agreement from using oral or external evidence to contradict, modify, or vary the terms of that written contract. This rule is based on the principle that if parties have put their agreement into a written document, it is assumed to be a complete and final representation of their intentions regarding the contract.

The purpose of the parol evidence rule is to provide certainty and stability in contractual agreements by ensuring that the written document is the only source of the terms that govern the relationship between the parties. Therefore, if a dispute arises, the court will rely solely on the content of the written contract rather than considering any prior negotiations or verbal statements that might suggest a different interpretation of the terms.

Understanding this rule is crucial because it emphasizes the importance of clear, comprehensive written agreements in business and personal transactions, safeguarding against misunderstandings that could arise from relying on informal conversations or unwritten agreements. This principle underscores the idea that once parties commit to a written contract, they are expected to stand by the terms as articulated within that document.