This law states that when someone promises to be responsible for someone else's debt at the same time that the debt itself is created, the promise doesn't need anything else to make it valid because it's part of the original deal. However, if this guarantee comes later, there needs to be something extra added to make it valid.

This law explains situations where someone promises to pay the debt of someone else, but this promise is considered their own original obligation, so it doesn't need to be written down. This can happen if they've received someone's property and agreed to use it as promised, or they're getting a benefit from making the promise. It can also occur if a creditor gives up something of value, the old debt is canceled for a new promise, or a person's property is released from seizure or they avoid imprisonment due to the promise. Other examples include a business agent pledging to sell goods for a commission while also acting as a guarantor, or when someone hands over a financial instrument as part of settling their own debt while making a promise about that instrument.

If someone offers to be a surety, which means they promise to take responsibility for another person's debt if they don't pay, that offer can be accepted either by taking action based on it or by accepting some other benefit. If the surety's promise is unconditional, they are bound by it even if they don't get a formal notice that their offer was accepted.