The rule: a promise to pay the debt of another person must be evidenced by some writing if it is a “collateral promise of suretyship (or ‘guaranty’).” A collateral promise is one secondary or ancillary to some other promise. Asurety or guarantor (the terms are essentially synonymous) is one who promises to perform upon the default of another. Consider this:
A and B agree to pay C.
Here, both A and B are making a direct promise to pay C. Although A is listed first, both are promising to pay C. Now consider this:
B agrees to pay C if A does not.
Here it is clear that there must be another agreement somewhere for A to pay C, but that is not contained in this promise. Rather, B is making an agreement with C that is collateral—on the side—to the promise A is making to C. Sometimes the other agreement somewhere for A to pay C is actually in the same document as B’s promise to pay C if A does not. That does not make B’s promise a direct promise as opposed to a collateral one.
Suppose Lydia wishes to purchase on credit a coat at Miss Juliette’s Fine Furs. Juliette thinks Lydia’s creditworthiness is somewhat shaky. So Lydia’s friend Jessica promises Miss Juliette’s that if the store will extend Lydia credit, Jessica will pay whatever balance is due should Lydia default. Jessica is a surety for Lydia, and the agreement is subject to the Statute of Frauds; an oral promise will not be enforceable. 1 Suppose Jessica very much wants Lydia to have the coat, so she calls the store and says, “Send Lydia the fur, and I will pay for it.” This agreement does not create a suretyship, because Jessica is primarily liable: she is making a direct promise to pay. To fall within the Statute of Frauds, the surety must back the debt of another person to a third-party promisee (also known as the obligee of the principal debtor). The “debt,” incidentally, need not be a money obligation; it can be any contractual duty. If Lydia had promised to work as a cashier on Saturdays at Miss Juliette’s in return for the coat, Jessica could become surety to that obligation by agreeing to work in Lydia’s place if she failed to show up. Such a promise would need to be in writing to be enforceable.
The exception: the main purpose doctrine. The main purpose doctrine is a major exception to the surety provision of the Statute of Frauds. It holds that if the promisor’s principal reason for acting as surety is to secure her own economic advantage, then the agreement is not bound by the Statute of Frauds writing requirement. Suppose, in the previous example, that Jessica is really the one who wants the fur coat but cannot, for reasons of prudence, let it be known that she has bought one. So she proposes that Lydia “buy” it for her and that she will guarantee Lydia’s payments. Since the main purpose of Jessica’s promise is to advance her own interests, an oral agreement is binding. Normally, the main purpose rule comes into play when the surety desires a financial advantage to herself that cannot occur unless she provides some security. For example, the board chairman of a small company, who also owns all the voting stock, might guarantee a printer that if his company defaulted in paying the bill for desperately needed catalogs, he would personally pay the bill. If his main purpose in giving the guarantee was to get the catalogues printed in order to stave off bankruptcy, and thus to preserve his own interest in the company, he would be bound by an oral agreement. 2 The same principle can be used to bind other creditors to oral agreements, as the bank discovered in The Statute of Frauds’ Main Purpose Doctrine (Wilson Floors).