Before 2005, the state did not tax transfers at death. In 2005, however, the legislature enacted a "stand-alone" estate tax on a prospective only basis that mirrored the federal estate tax (where QTIP property is subject to tax in the surviving spouse's estate). The state then adopted a regulation that taxed QTIP assets when the surviving spouse after the legislative change but where the first spouse had died before the effective date of the 2005 legislative change. The Washington Supreme Court later invalidated the regulation by interpreting "transfer" narrowly and holding that the only "transfer" subject to tax occurred at the time the QTIP trusts at issue in the case were created. In re Estate of Bracken, 175 Wash.2d 549, 290 P.3d 99 (2012). The state of Washington amended its Estate and Transfer Tax Act in 2013 to provide that the tax on QTIP trust assets upon the death of the surviving spouse applies prospectively and retroactively to all estates of decedents dying on or after May 17, 2005. In the case at issue, the question was whether the 2013 law's retroactive application was permissible insomuch that retroactive application taxed interests that had previously not been taxable. The court upheld the constitutionality of the law, finding that it did not violate either the separation of powers doctrine, due process clause or the impairment of contracts clause. In re Estate of Hambleton, No. 89419-1, 2014 Wash. LEXIS 773 (Wash. Sup. Ct. Oct. 2, 2014).