MBE Rules · Contracts
Parol evidence rule
The rule
When parties have a fully integrated written agreement, prior or contemporaneous oral statements that contradict or vary the writing are inadmissible. A merger clause is strong (but not conclusive) evidence of full integration. Partial integrations may be supplemented by consistent additional terms.
In plain English
If you have a complete written contract, you can't use earlier spoken agreements to change it. Sometimes, you can add details that don't conflict with the written terms.
Worked example
The buyer and seller sign a contract for a car sale. The buyer can't later claim an oral promise for free servicing was part of the deal, as it wasn't in the written contract.
Memory hook
If it's in writing, no rewriting! Full integration means no oral changes—what's written rules.
The trap
Students think: any oral statement is inadmissible. Wrong, because consistent additional terms can supplement partial integrations. The actual test is whether the writing is fully integrated.
How examiners test it
The MBE loves: a contract with a merger clause + prior oral agreement. Trap: assuming merger clause is conclusive. Must determine if writing is fully integrated or partial.
Drill this rule until it can't fail you.
Vrenberg generates unlimited questions on this exact rule, tracks your mastery of it, and brings it back until it sticks.