general testamentary power of appointment

In 1930 a New York resident created a revocable trust that was amended in 1931. The trust directed income from the corpus to his wife for life. It also granted her a general power of appointment. In default of appointment half the corpus passed to the decedent's heirs and half to the wife's heirs. In 1951 the wife executed an instrument that purported to release the general power and convert it into a special power. The decedent died in 1957. His estate claimed a marital deduction for the widow's trust on the federal estate tax return. The Commissioner disallowed the deduction under section 2056(b)(5) of the 1954 Code and assessed a deficiency. The estate petitioned the Tax Court for redetermination. While that proceeding was pending the estate obtained a New York Supreme Court decree declaring the 1951 release a nullity. The Tax Court accepted the decree as controlling and allowed the deduction. A divided Second Circuit affirmed. The companion case involved the estate of a Connecticut decedent who died in 1958. His will directed payment of estate taxes without proration and created a residuary trust granting his wife a general testamentary power of appointment. The Commissioner disallowed part of the marital deduction. The executor then obtained a probate court order applying the state proration statute. The District Court refused to treat the probate decree as binding on federal tax questions. The Second Circuit agreed the decree was not conclusive. The two cases reached the Supreme Court after the Second Circuit panels reached differing conclusions on the effect of the state decrees. Certiorari was granted to resolve the conflict among the circuits.