Enforceable contracts are the bedrock of a strong economy. If contracts were not enforced, parties could not rely on the other side performing because there would be no remedy if they breached. Therefore, commerce would break down. Enforceable contracts are so important to the economy, in fact, that the freedom to contract is included in both the New Jersey and United States Constitutions. Before a contract can be enforced, however, the parties and the reviewing court must figure out what the contract means. When the terms are clear this normally isn’t a problem. However, when the contract is ambiguous, or even just a part of it is unclear, the question becomes what evidence may be admitted to determine the meaning and intent of the contract.
As I’ve written earlier, New Jersey courts generally adhere to the “parole evidence rule,” which holds that when there is a clear, unambiguous contract, extrinsic, or external, evidence beyond the four walls of the contract is inadmissible to prove what the contract means. However, in New Jersey business law, the exceptions come close to swallowing the rule. Indeed, the New Jersey Supreme Court held as far back as 1953, in the case of Atlantic Northern Airlines v. Schwimmer, that all evidence is relevant if it will assist the trier of fact in determination what the parties to a contract intended and what the contract means – even if that evidence is extrinsic.
The question, then, is what sort of extrinsic evidence is admissible? In the case of commercial contracts, one source of evidence is custom and usage.