Upon the death of a married person, one-half of the property to which this part applies is the property of the surviving spouse and is not subject to testamentary disposition by the decedent nor to the laws of descent and distribution. One-half of that property is the property of the decedent and is subject to testamentary disposition by the decedent or the law of descent and distribution. With respect to property to which this part applies, the one-half of the property which is the property of the decedent is not subject to the surviving spouse's right to elect against the will.