Neb. Rev. Stat. § 36-813: Neb. Rev. Stat. § 36-813

Unless displaced by the provisions of the Uniform Voidable Transactions Act, the principles of law and equity, including the law merchant and the law relating to principal and agent, estoppel, laches, fraud, misrepresentation, duress, coercion, mistake, insolvency, or other validating or invalidating cause, supplement its provisions.