The Defense of Marriage Act was passed by the United States Congress, prohibiting federal recognition of same-sex marriage, while allowing states to adopt any marital definition of their choosing.

The Defense of Marriage Act (DOMA) was a United States federal law passed by the 104th United States Congress and signed into law by President Bill Clinton on September 21, 1996. It banned federal recognition of same-sex marriage by limiting the definition of marriage to the union of one man and one woman, and it further allowed states to refuse to recognize same-sex marriages granted under the laws of other states.

The United States Congress is the legislative branch of the federal government of the United States. It is a bicameral legislature, including a lower body, the U.S. House of Representatives, and an upper body, the U.S. Senate. They both meet in the United States Capitol in Washington, D.C.

The legal recognition of same-sex marriage in the United States expanded from one state in 2004 (Massachusetts) to all fifty states in 2015 through various court rulings, state legislation, and direct popular vote. States have separate marriage laws, which must adhere to rulings by the Supreme Court of the United States that recognize marriage as a fundamental right guaranteed by both the Due Process Clause and the Equal Protection Clause of the Fourteenth Amendment to the United States Constitution, as first established in the 1967 landmark civil rights case of Loving v. Virginia.