MBE Rules · Contracts
Main Purpose Rule
Main purpose rule
The rule
An oral promise to answer for another's debt is enforceable despite the suretyship statute when the promisor's main purpose is her own economic benefit.
In plain English
The Main Purpose Rule states that if someone makes an oral promise to pay another person's debt, that promise can be enforced if the main reason for making the promise is to benefit themselves financially. This means that even if the promise isn't in writing, it can still be valid if the promisor stands to gain from it.
Worked example
Alice promises to pay Bob's debt to Charlie because she wants to secure a lucrative contract with Charlie for her business. Since Alice's main purpose in making the promise is to benefit her own economic interests, her oral promise is enforceable despite the lack of a written agreement. Therefore, Charlie can hold Alice accountable for Bob's debt.
Memory hook
If it's for your gain, your word's your bond, even without a written contract!
The trap
Students often overlook the requirement that the promisor's main purpose must be their own economic benefit, mistakenly thinking that any promise to pay another's debt is enforceable regardless of motive.
How examiners test it
Questions typically present a scenario involving an oral promise to pay a debt and ask whether the promise is enforceable, often including details about the promisor's motivations to test understanding of the Main Purpose Rule.
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