Cal. Civil Code § 1578 : Nature Of A Contract — California Civil Code — Obligations — Consent — Mistake of law Date: 14 Sep 2016 TEXT PDF Current through the 2016 Legislative Session 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 contracting, but which they do not rectify. Ca. Civ. Code § 1578