Cal. Civil Code § 1577 : Nature Of A Contract — California Civil Code — Obligations — Consent — Mistake of fact Date: 14 Sep 2016 TEXT PDF Current through the 2016 Legislative Session Mistake of fact is a mistake, not caused by the neglect of a legal duty on the part of the person making the mistake, and consisting in: 1.An unconscious ignorance or forgetfulness of a fact past or present, material to the contract; or, 2. Belief in the present existence of a thing material to the contract, which does not exist, or in the past existence of such a thing, which has not existed. Ca. Civ. Code § 1577