Under the best evidence rule,evidence of oral statements made before signing a written agreement is admissible in court to change the terms of a written agreement.

Under the best evidence rule, primary evidence (i.e. the original written agreement) is preferred over secondary evidence (i.e. oral statements about the agreement). Therefore, oral statements made before signing a written agreement are generally not admissible to change the terms of the written agreement. However, there are some exceptions to this rule, such as when the written agreement is incomplete, ambiguous, or subject to fraud.