Economics
The Parol Evidence Rule in Contract Interpretation
Quick fact
The parol evidence rule can exclude evidence of verbal promises made before signing a contract, even if those promises were genuinely made and relied upon, unless the contract is found to be incomplete or ambiguous.
Why this is interesting
Imagine you sign a written contract for a used car, but the seller later claims you agreed verbally to a lower price before signing. Should the court listen to that verbal promise? The parol evidence rule might say no.