Marriage has traditionally been regulated through custom, religion, and law. Legal and social responses to the fairly recent institution of same-sex marriage has varied around the world from acceptance and legalization, and in ten countries, to criminalization. In the United States, the authority to decide who can legally marry is primarily regulated by the states, which has resulted in a patchwork of laws and regulations.
As of August 2012, six states allow marriages between same sex couples: Connecticut, Iowa, Massachusetts, New Hampshire, New York, and Vermont. Washington D.C. also allows same-sex marriages. Two states, Maryland and Rhode Island, recognize marriages performed in jurisdictions where they are legal but do not perform them. California recognizes marriages performed in the state during the brief period in 2008 when same-sex marriages were legal. Five states currently recognize civil unions, a legally-recognized union similar to, but in some cases lacking some of the legal benefits of, marriage. These states are Delaware, Hawaii, Illinois, New Jersey, and Rhode Island. As of May 2012, 39 states ban same-sex marriage by either constitutional amendment or law.
Prior to 1996, the marriage issue was solely the provenance of the states. However, in 1996 the federal government passed the Defense of Marriage Act (DOMA) to "define and protect the institution of marriage." This act created a federal definition of marriage as being between one man and one woman, and gave individual states the right not to recognize same-sex marriages that were legally performed in other states. As a result, same-sex marriages may be recognized at the state level depending on the laws of that state, but no same sex marriage is recognized at the federal level. States may permit or recognize same-sex marriages but cannot extend the many federal benefits and protections of marriage to these couples. These include social security survivor benefits, immigration rights that come with marrying an American and the ability to file a joint federal tax return. While DOMA is still federal law, the Obama administration has recognized federal court rulings that the law interferes with the right of the states to define marriage, and denies married same-sex couples the same federal benefits given to heterosexual married couples. In 2011, President Obama announced that the U.S. Department of Justice would no longer defend the constitutionality of the law. DOMA has not been struck down, but it is expected that appeals will eventually result in the constitutionality of the law being determined by the U.S. Supreme Court. Republican presidential candidate Mitt Romney does not support same sex marriage, and if elected, would likely order the Justice Department to defend DOMA vigorously in the courts. Several attempts in the U.S. House and Senate to amend the U.S. Constitution to define marriage have thus far failed to gain the number of votes needed to move forward.
Hawaii's state Supreme Court ruled in 1993 that laws prohibiting same-sex marriage violated the state constitution's equal rights protection. This ruling triggered the gay marriage debate in the U.S., a controversial issue that continues today. Same-sex marriage remains illegal in Hawaii due to a state constitutional amendment that passed via popular vote shortly after the high court ruling. Prior to 2004, four states banned same-sex marriage via constitutional amendment. In 2004, popular votes in 13 states added constitutional amendments defining marriage as between one man and one woman. Fourteen more states followed suit between 2005 and 2010. The most recent state to approve a constitutional amendment was North Carolina, in 2012, bringing the total number of states with constitutional amendments defining marriage to 31. In 1999, the Vermont Supreme Court ruled that prohibiting marriage to same-sex couples violated the state constitution. As a result, the state legislature passed a law creating civil unions, becoming the first state to do so. The civil union system remained in effect in Vermont until the state legalized same-sex marriage in 2009. Massachusetts became the first state to legalize same-sex marriage, in 2003, when the state Supreme Court ruled that outlawing such marriages violated the Massachusetts constitution. The state began issuing marriage licenses to same-sex couples in May 2004. Since then, heated battles have been fought in several states. Notably, in California, same-sex marriages were legalized by a California Supreme Court ruling in 2008. However, opponents gathered enough signatures to force a popular vote on a state constitutional amendment, Proposition 8. The amendment passed on November 5, 2008, and as a result same-sex marriage became illegal, but the state recognizes same-sex marriages that were legally performed before that date. A federal judge ruled in 2010 that the amendment violated equal-protection provisions, and that decision was upheld by the federal appellate court. It remains to be seen whether the U.S. Supreme Court will hear the matter. The New Jersey legislature passed a bill legalizing same-sex marriage in February 2012, but the measure was vetoed by Governor Chris Christie. Washington and Maryland legalized same sex marriage in 2012, but the laws have not gone into effect in either state; opponents gathered enough signatures to put the issue on the ballot in November. Maine will also vote on an initiative to legalize same-sex marriage on November 6, 2012.