Prob. Code, § 147

(a) Subject to subdivisions (c) and (d), a waiver, agreement, or property settlement made after December 31, 1984, is invalid insofar as it affects the rights listed in subdivision (a) of Section 141 unless it satisfies the requirements of this chapter.

(b) Nothing in this chapter affects the validity or effect of any waiver, agreement, or property settlement made prior to January 1, 1985, and the validity and effect of such waiver, agreement, or property settlement shall continue to be determined by the law applicable to the waiver, agreement, or settlement prior to January 1, 1985.

(c) Nothing in this chapter affects the validity or effect of any premarital property agreement, whether made prior to, on, or after January 1, 1985, insofar as the premarital property agreement affects the rights listed in subdivision (a) of Section 141, and the validity and effect of such premarital property agreement shall be determined by the law otherwise applicable to the premarital property agreement. Nothing in this subdivision limits the enforceability under this chapter of a waiver made under this chapter by a person intending to marry that is otherwise enforceable under this chapter.

(d) Nothing in this chapter limits any right one spouse otherwise has to revoke a consent or election to disposition of his or her half of the community or quasi-community property under the will of the other spouse.