(1) If as a result of a controversy involving the decedent's will, or involving any bequest or devise thereunder, his surviving spouse assigns or surrenders a property interest in settlement of the controversy, the interest so assigned or surrendered is not considered as having “passed from the decedent to his surviving spouse.”
(2) If as a result of the controversy involving the decedent's will, or involving any bequest or devise thereunder, a property interest is assigned or surrendered to the surviving spouse, the interest so acquired will be regarded as having “passed from the decedent to his surviving spouse” only if the assignment or surrender as a bona fide recognition of enforceable rights of the surviving spouse in the decedent's estate. Such a bona fide recognition will be presumed where the assignment or surrender was pursuant to a decision of a local court upon the merits in an adversary proceeding following a genuine and active contest. However, such a decree will be accepted only to the extent that the court passed upon the facts upon which deductibility of the property interest depends. If the assignment or surrender was pursuant to a decree rendered by consent, or pursuant to an agreement not to contest the will or not to probate the will, it will not necessarily be accepted as a bona fide evaluation of the rights of the spouse.