Florence Sheldon and Al Sheldon were married in January of 1974. In 1972, Florence drafted a valid holographic will that directed the residue of her estate to be divided between her two children from another marriage, Oscar Marion Huffman (Marion) (plaintiff) and Helen Peterson. Florence passed away in September 1974. Al assigned his interest in Florence’s estate to Mr. and Mrs. Peterson (defendants). Marion filed a claim to determine heirship in Florence’s estate, and the Petersons filed a claim for both their share and Al’s share. Marion alleged that an oral antenuptial agreement existed between Al and Florence by which each party had agreed to waive his or her claim in the other’s estate, which barred the application of California Probate Code (Probate Code) section 220. The trial court, using an advisory jury, found that an oral antenuptial agreement existed and that Florence, by marrying Al, had changed her position to her detriment. The trial court held that because the agreement had been fully performed, the Petersons were estopped from raising the statute of frauds. The Petersons appealed.