Mistake of Law

A mistake of law constitutes a mistake within the meaning of this Article 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 the contracting, but which they do not rectify.