N.D. Cent. Code § 9-03-14: Mistake of law defined

Mistake of law constitutes a mistake within the meaning of this title only when it arises from:

1.A misapprehension of the law by all parties, all supposing that they knew and understood it and all making substantially the same mistake as to the law; or

2.A misapprehension of the law by one party of which the others are aware at the time of contracting, but which they do not rectify.