Okla. Stat. tit. 12, § 12-729.14: Principles of law and equity - Construction of act

Unless displaced by particular provisions of this act, the

principles of law and equity, including the law merchant, and the

law relative to capacity to contract, principal and agent, estoppel,

fraud, misrepresentation, duress, coercion, mistake, bankruptcy or

other validating or invalidating causes supplement its provisions.