Service Contracts - Parol Evidence Rule and Ethics

Answer the following question in a manner that is clear and concise. Write so that the lay person can understand your answer. Your response must explain the law involved in arriving at your conclusion. No points will be assigned for unsupported conclusions.

In entering into contracts for services, customers might be influenced by statements made by sales representatives. Businesses offering services often use standardized form contracts. Under the parol evidence rule, pre-contract statements made in these circumstances are effectively unenforceable. How can a business effectively and ethically use standardized form contracts and the parol evidence rule.