California Code
TITLE 2 - MANNER OF CREATING CONTRACTS
Section 1623.

1623. Where a contract, which is required by law to be in writing, is prevented from being put into writing by the fraud of a party thereto, any other party who is by such fraud led to believe that it is in writing, and acts upon such belief to his prejudice, may enforce it against the fraudulent party.

(Enacted 1872.)