The principles of law and equity, including the law of corporations and any other form of organization authorized by the law of this state and unincorporated associations, the law of real estate, and the law relative to the capacity to contract, principal and agent, eminent domain, estoppel, fraud, misrepresentation, duress, coercion, mistake, receivership, substantial performance, or other validating or invalidating cause supplement this chapter, except to the extent inconsistent with this chapter.
RCW 64.90.035