Michigan Compiled Laws, Chapter 440. Uniform Commercial Code § 440.1103

Sec. 1103.(1) This act must be liberally construed and applied to promote the following underlying purposes and policies:

(2) Unless displaced by the 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 cause shall supplement its provisions.