Civil union in the United States

Same-sex unions in the United States are available in various forms in all states and territories, except American Samoa. All states have legal same-sex marriage, while others have the options of civil unions, domestic partnerships, or reciprocal beneficiary relationships. The federal government only recognizes marriage and no other legal union for same-sex couples.

Hawaii was the first state to recognize limited legal same-sex unions, doing so in 1997 in the form of reciprocal beneficiary partnerships.

The legal issues surrounding same-sex marriage in the United States are complicated by the nation's federal system of government. Traditionally, the federal government does not attempt to establish its own definition of marriage. Instead, any marriage recognized by a state was recognized by the federal government, even if that marriage was not recognized by one or more other states (as was the case with interracial marriage before 1967 due to anti-miscegenation laws). According to the federal General Accounting Office (GAO), more than 1,138 rights and protections are conferred to U.S. citizens upon marriage by the federal government; areas affected include Social Security benefits, veterans' benefits, health insurance, Medicaid, hospital visitation, estate taxes, retirement savings, pensions, family leave, and immigration law.

The federal Defense of Marriage Act in 1996, prompted by fears of an adverse result in Hawaii's lawsuit Baehr v. Miike, defined a marriage explicitly as a union of one man and one woman for the purposes of all federal laws (See 1 U.S.C. § 7), which was ultimately ruled unconstitutional by the Supreme Court in United States v. Windsor on June 26, 2013. As a result, shortly after Windsor was decided, a number of federal areas ranging from veteran benefits to immigration were clarified as applying equally to same-sex couples.

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