CA Prob Code Section 143

(a)

Subject to Section 142, a waiver is enforceable under this section unless the surviving spouse proves either of the following:

(1)

A fair and reasonable disclosure of the property or financial obligations of the decedent was not provided to the surviving spouse prior to the signing of the waiver unless the surviving spouse waived such a fair and reasonable disclosure after advice by independent legal counsel.

(2)

The surviving spouse was not represented by independent legal counsel at the time of signing of the waiver.

(b)

Subdivision (b) of Section 721 of the Family Code does not apply if the waiver is enforceable under this section.