Read Probate Code §§ 144 – 144.

        An enforceable marital settlement agreement can lead to a waiver of spousal rights. In Welch v. Welch, B311507 (2/5  5/31/22) (Moor, Rubin, Kim), a husband and wife, anticipating the dissolution of their marriage, entered into a marital settlement agreement (MSA) to distribute their property. The court entered judgment, the wife died, and the surviving husband sought to undo the settlement agreement. He succeeded in the trial court, but failed in the Court of Appeal. 

        The issue was whether the surviving spouse, the husband, waived spousal rights enumerated in the Probate Code, § 141(a) by entering into the MSA. The Court of Appeal held that the MSA was enforceable, because it was a complete property settlement, the parties were represented by counsel, and the husband had  received a "fair and reasonable disclosure of the property or financial obligations" of his wife.