Defense of Marriage Act (DOMA)
Passed in 1996, The Defense of Marriage Act (DOMA) denies federal recognition of gay marriages and gives each state the right to refuse recognition of same-sex marriage licenses issued by other states. The act does not prohibit states from allowing gay marriages, but neither does it obligate states to recognize the gay marriages from other states. For the first time in history, the federal government defines marriage in the Act as a "legal union between one man and one woman as husband and wife," and spouse is defined as "a person of the opposite sex who is a husband or a wife." Marriages that do not fit this description are not eligible for any benefits offered by the federal government.
For More Information on DOMA, see Senate Subcommittee Hearing on the Proposed Federal Defense of Marriage Act.