In the American federal system, state governments bear the responsibility for enacting the laws that define the persons who are permitted to marry. The federal government, throughout our history, has accepted these definitions and built upon them, fixing legal consequences for those who validly marry under state law. Only twice in American history has Congress intervened to reject the determinations that states might make about who can marry. The first occasion was in the late nineteenth century when Congress enacted a series of statutes aimed at the Mormon Church, prohibiting polygamy in the Western territories and punishing the Church and those within it who entered into polygamous marriages. The more recent occasion was just last year. In the summer of 1996, Congress adopted the Defense of Marriage Act, which provides that, regardless of state laws, all acts of Congress referring to married persons shall be read as applying only to persons married to a person of the opposite sex.
Chambers, David L. "Polygamy and Same-Sex Marriage." Hofstra L. Rev. 26, no. 1 (1997): 53-83.