On June 26, the United States Supreme Court struck down Section Three of the federal Defense of Marriage Act ("DOMA") as unconstitutional because it deprives individuals of equal liberty protections provided by the Fifth Amendment of the Constitution.

The case was brought by a lesbian widow whose same-sex marriage was recognized under New York law. The widow sought an IRS refund of taxes she paid on her spouse's estate after being denied the right to claim the federal estate tax exemption for surviving spouses. The United States took the position that Section Three of DOMA, which defines "marriage" and "spouse" as excluding same-sex partners under federal law, precluded the widow from claiming the exemption. The district court ruled against the United States and ordered the Treasury to refund the widow. The United States Court of Appeals for the Second Circuit affirmed that decision, and the case was appealed to the Supreme Court. In affirming the Second Circuit decision and holding that Section Three is unconstitutional, the Supreme Court reasoned that regulation of domestic matters is an area that is within the province of states. The DOMA provision rejects this well-established precept by providing a federal definition for "marriage" that seeks to injure the very class of individuals that New York law sought to protect by recognizing same-sex marriages. In so doing, DOMA requires unequal treatment of a subset of state-sanctioned marriages such that same-sex couples are held to different standards depending on which law is applied. As such, this provision violates basic due process and equal protection principles by depriving same-sex couples of many of the benefits and responsibilities that come with a federally-recognized marriage. While the decision concerns a same-sex couple's right to equal treatment regarding an estate tax refund, the Supreme Court noted that Section Three of DOMA affects over 1,000 statutes and federal regulations, including laws pertaining to Social Security, housing, taxes, criminal sanctions, copyright, and veterans' benefits, which have treated same-sex couples whose marriages have been recognized by a state differently from heterosexual couples married in the same state. Read more.