California
Civil Code
 
Section 1578

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.

  • Bluebook

    CA​Civ​§​1578
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