Thus Sunstate argues that it was error for the trial court to exclude evidence that the building agreement had been orally modified. In Wendell v. Foley, 92 N.M. 702, 705, 594 P.2d 750, 753 (Ct.App.), cert. denied, 92 N.M. 675, 593 P.2d 1078 (1979), the Court of Appeals noted that "in the absence of a prohibiting statute, a written contract may be orally modified by the parties who made the original agreement." The Court also noted that oral modifications may be made even though the contract itself requires all modifications to be in writing.

Although the guaranty on its face required all changes to be in writing, oral modifications to a written contract are permissible under certain circumstances even when the contract specifies that modifications must be in writing. Medina v. Sunstate Realty, Inc., 119 N.M. 136, 138-39, 889 P.2d 171, 173-74 (1995) (stating that a district court erred by excluding evidence of oral modification to a written contract specifying that all changes must be in writing); Wendell v. Foley, 92 N.M. 702, 705, 594 P.2d 750, 753 (Ct.App. 1979) (holding that there may be oral modification to a written contract specifying that all changes must be in writing). We also reject Bank's assertions that the statute of frauds precludes the Hilburns from asserting an oral agreement because the guaranty is covered by the statute of frauds as an agreement to guaranty the debt of another.

See Hannah, 589 P.2d at 1037. The defendant bears the burden of proving an affirmative defense,Wendell v. Foley, 92 N.M. 702, 594 P.2d 750 (Ct.App. 1979), cert. denied, even if he must assert a negative, see Kuchan v.Strong, 39 N.M. 281, 46 P.2d 55 (1935). At trial, the Buslees did not testify that a search of the relevant land records had failed to produce a properly recorded power of attorney; they offered no evidence suggesting that there was none.

New Mexico law provides "that 'in the absence of a prohibiting statute, a written contract may be orally modified by the parties who made the original agreement.'" Medina v. Sunstate Realty, Inc., 889 P.2d 171, 173 (N.M. 1995) (quoting Wendell v. Foley, 594 P.2d 750, 753 (N.M. Ct. App.), cert. denied, 593 P.2d 1078 (N.M. 1979) (internal citation omitted)). "A modification occurs when the parties intend to continue the contractual relationship but wish to change one or more of the terms of the contract.

That is not the proper function of an appellate court. Wendell v. Foley, 92 N.M. 702, 594 P.2d 750 (Ct.App. 1979). (3) To justify liquidation pursuant to § 53-16-16, N.M.S.A. 1978, the trial court would have had to find that the conduct of those in control of the corporation was "illegal, oppressive or fraudulent" or that corporate assets were wasted.

Stewart v. Barnes, 80 N.M. 102, 451 P.2d 1006 (Ct.App. 1969).Under the circumstances of this case, with evidence that Hernandez screamed for help loud enough for the entire jail to hear, and that no jailer came around while Hernandez was being beaten; and in view of the trial court's explicit findings not only that it was defendants' duty, not plaintiff's, to determine where prisoners would be confined, but that by reason of the severe beating Hernandez could not "intelligently be held accountable for his actions and conduct" in protection of himself, we adhere to the long-standing appellate rule of upholding the decision of the fact-finder if it is supported by findings which are sustained by the evidence. Wendell v. Foley, 92 N.M. 702, 594 P.2d 750 (Ct.App. 1979). Simply because defendants believe the evidence could have supported different findings and conclusions, we are not free to substitute that judgment, or our own, for the judgment of the fact-finder.