Trustee could not use statute of frauds and SS 544 to avoid a personal guaranty because it was an affirmative defense unique to the debtor. Further, the trustee could not step into the shoes of the debtor under SS 541 to assert the statute of frauds because the debtor previously waived the defense to the guaranty when he paid it. The case also discusses the Main Purpose and Partial Performance exceptions to the statute of frauds. Finally, the effective date stated in the guaranty controlled even though it was signed some months later. The Court thus rejected the trustee's theories to avoid the guaranty obligation.