California Code, Probate Code - PROB § 21385

(a) An at-death transfer, as defined in Section 21104, between spouses by will, revocable trust, beneficiary form, or other instrument is not subject to Section 721 of the Family Code or any presumptions of undue influence created by that section.

(b) This section does not limit the application of any other statutory or common law presumptions of undue influence that may apply to an at-death transfer between spouses.