In the United States, same-sex marriage is legal in all states, Washington, D.C., U.S. territories except American Samoa, but not on all Native American tribal lands. Same-sex marriage has been legal since June 26, 2015, when the United States Supreme Court ruled in Obergefell v. Hodges that state-level bans on same-sex marriage are unconstitutional.  The court ruled that the denial of marriage licenses to same-sex couples and the refusal to recognize those marriages performed in other jurisdictions violates the Due Process and the Equal Protection clauses of the Fourteenth Amendment of the United States Constitution. The ruling overturned a 1972 precedent, Baker v. Nelson. Just prior to the Supreme Court's ruling in 2015, same-sex marriage was legal in many but not all U.S. jurisdictions.
While civil rights campaigning took place from the 1970s,  the issue became prominent from around 1993, when the Hawaii Supreme Court ruled in Baehr v. Lewin that the prohibition was unconstitutional. The ruling led to federal actions and actions by several states, to restrict marriage to male-female couples, in particular the Defense of Marriage Act (DOMA). During the period of 2003 to 2015, various lower court decisions, state legislation, and popular referendums already legalized same-sex marriage to some degree in thirty-eight out of fifty U.S. states, in the U.S. territory of Guam, and in the District of Columbia. In 2013, the Supreme Court overturned a key provision of DOMA, declaring part of it unconstitutional and in breach of the Fifth Amendment in United States v. Windsor because it "single[d] out a class of persons" for discrimination, by refusing to treat their marriages equally under federal law when state law had created them equally valid. The ruling led to the Federal Government's recognition of same-sex marriage, with federal benefits for married couples connected to either the state of residence or the state in which the marriage was solemnized. However, the ruling focused on the provision of DOMA responsible for the Federal Government refusing to acknowledge state sanctioned same-sex marriages, leaving the question of state marriage laws itself to the individual states. The Supreme Court addressed that question two years later in 2015, ruling, in Obergefell, that same-sex married couples were to be constitutionally accorded the same recognition as opposite-sex couples at state/territory levels, as well as at federal level.
By the time that same-sex marriage became legal nationally, public opinion on the subject reached almost 60% approval levels according to polls by The Wall Street Journal, the Human Rights Campaign,  and CNN, having crossed the 50% in 2011 and not going below that mark since. 
The movement to obtain civil marriage rights and benefits for same-sex couples in the United States began in the 1970s.  In the 1971 case Baker v. Nelson, the Minnesota Supreme Court ruled that denying marriage licenses to same-sex couples did not violate the U.S. Constitution. On appeal, the United States Supreme Court denied to hear the case, establishing it as a federal precedent as it came from mandatory appellate review. The issue did not become prominent in U.S. politics until the 1993 Hawaii Supreme Court decision in Baehr v. Lewin that declared that state's prohibition to be unconstitutional. 
During the 21st century, while several countries elsewhere in the world were opening marriage for same-sex couples, public support in the U.S. for same-sex marriage has grown considerably,   and national polls conducted since 2011 show that a majority of Americans support legalizing it. However at the same time, many states also passed bans against same-sex marriage, either legislatively or by referendum.  On May 17, 2004, Massachusetts became the first U.S. state and the sixth jurisdiction in the world to legalize same-sex marriage following the Supreme Judicial Court's decision in Goodridge v. Department of Public Health six months earlier. On May 9, 2012, Barack Obama became the first sitting U.S. President to publicly declare support for the legalization of same-sex marriage.  On November 6, 2012, Maine, Maryland and Washington became the first states to legalize same-sex marriage through popular vote.
In June 2013, the Supreme Court ruled in United States v. Windsor that federal law could not treat as unequal, marriages that individual states had created as equally valid, when it overturned a key provision of the Defense of Marriage Act (DOMA), thus forcing federal recognition of same-sex marriage and marriage-related benefits when related to a same-sex marriage performed by a state that sanctioned such marriages. In the two years following Windsor, U.S. district courts in 27 states and state courts in six states, plus one state court ruling addressing only the recognition of same-sex marriages from other jurisdictions, found that same-sex marriage bans violate the U.S. Constitution, while two U.S. district courts and one state court found that they did not. The flow of federal appeal cases rejecting same-sex marriage bans was finally interrupted in November 2014. In contrast to all other circuits that had ruled at the time, the Sixth Circuit ruled such bans to be constitutional. The panel ruling reversed six U.S. district court rulings that had found bans on same-sex marriage or its recognition to be unconstitutional, reinstating State bans in the four states served by that circuit (Kentucky, Michigan, Ohio and Tennessee). 
On January 16, 2015, the U.S. Supreme Court agreed to hear four cases, on appeal from the Sixth Circuit, on whether states may constitutionally ban same-sex marriages or refuse to recognize such marriages legally performed in another state. The cases were: Obergefell v. Hodges (Ohio), Tanco v. Haslam (Tennessee), DeBoer v. Snyder (Michigan), and Bourke v. Beshear (Kentucky). Decided by the court under the heading of Obergefell on June 26, 2015, a 5–4 majority of justices led by Justice Anthony Kennedy reversed the Sixth Circuit's upholding of state bans and declared that the Court's rulings must evolve in the light of better understanding of discrimination and the constitutional protections available to protect minorities, and that same-sex couples have the constitutional rights to marry and to have their marriages recognized.  Obergefell therefore overturned the Court's own prior ruling in Baker.
Prior to Obergefell, same-sex marriage was legal to at least some degree in thirty-eight states, one territory (Guam) and the District of Columbia; of the states, Missouri, Kansas, and Alabama had restrictions. Until United States v. Windsor, it was only legal in 12 states and Washington D.C.. Beginning in July 2013, over forty federal and state courts cited Windsor to strike down state bans on the licensing or recognition of same-sex marriage. Missouri recognized same-sex marriages from out of state and same-sex marriages licensed by the City of St. Louis under two separate state court orders; two other jurisdictions issued such licenses as well. In Kansas, marriage licenses were available to same-sex couples in most counties, but the state did not recognize their validity. Some counties in Alabama issued marriage licenses to same-sex couples for three weeks until the state Supreme Court ordered probate judges to stop doing so. That court's ruling did not address the recognition of same-sex marriages already licensed in Alabama, but referred to them as "purported 'marriage licenses ' ".  In two additional states, same-sex marriages were previously legal between the time their bans were struck down and then stayed. Michigan recognized the validity of more than 300 marriage licenses issued to same-sex couples and those marriages. Arkansas recognized the more than 500 marriage licenses issued to same-sex couples there,  and the Federal Government had not taken a position on Arkansas's marriage licenses.
The legal issues surrounding same-sex marriage in the United States are determined by the nation's federal system of government, in which the status of a person, including marital status, is determined in large measure by the individual states. Prior to 1996, the Federal Government did not define marriage; any marriage recognized by a state was recognized by the Federal Government, even if that marriage was not recognized by one or more states, as was the case until 1967 with interracial marriage, which some states banned by statute.
Prior to 2004, same-sex marriage was not performed in any U.S. jurisdiction. It was subsequently legalized in different jurisdictions through legislation, court rulings,  tribal council rulings,  and popular vote in referenda.   
The Supreme Court's ruling in Obergefell renders moot any remaining legal challenges, as it specifically orders states to both issue marriage licenses to same-sex couples, and to recognize as valid marriages performed in other states. 
According to the Federal Government's Government Accountability Office (GAO) in 2004, 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. 
Since July 9, 2015, married same-sex couples throughout the United States have equal access to all the federal benefits that married opposite-sex couples have. 
The Defense of Marriage Act (DOMA) was enacted in 1996. DOMA's Section 2 says that no state needs to recognize the legal validity of a same-sex relationship even if recognized as marriage by another state. It purports to relieve a state of its reciprocal obligation to honor the laws of other states as required by the Constitution's full faith and credit clause.  Even before DOMA, however, states sometimes refused to recognize a marriage from another jurisdiction if it was counter to its "strongly held public policies".  Most lawsuits that seek to require a state to recognize a marriage established in another jurisdiction argue on the basis of equal protection and due process, not the full faith and credit clause.
DOMA's Section 3 defined marriage for the purposes of federal law as a union of one man and one woman.  It was challenged in the federal courts. On July 8, 2010, Judge Joseph Tauro of the District Court of Massachusetts held that the denial of federal rights and benefits to lawfully married Massachusetts same-sex couples is unconstitutional under the equal protection clause of the U.S. Constitution. Beginning in 2010, eight federal courts found DOMA Section 3 unconstitutional in cases involving bankruptcy, public employee benefits, estate taxes, and immigration.    On October 18, 2012, the Second Circuit Court of Appeals became the first court to hold sexual orientation to be a quasi-suspect classification and applied intermediate scrutiny to strike down Section 3 of DOMA as unconstitutional in Windsor v. United States.  The U.S. Supreme Court ruled in Windsor on June 26, 2013, that Section 3 violated the Fifth Amendment. 
As a result of the Windsor decision, married same-sex couples—regardless of domicile—have federal tax benefits (including the ability to file joint federal income tax returns), military benefits, federal employment benefits, and immigration benefits.     In February 2014, the Justice Department expanded federal recognition of same-sex marriages to include bankruptcies, prison visits, survivor benefits and refusing to testify against a spouse.  Likewise in June 2014, family medical leave benefits under the Family Medical Leave Act 1975 were extended to married same-sex couples.  With respect to social security and veterans benefits, same-sex married couples are eligible for full benefits from the Veterans Affairs (VA) and the Social Security Administration (SSA). Prior to the Supreme Court's ruling in Obergefell v. Hodges on June 26, 2015, the VA and SSA could provide only limited benefits to married same-sex couples living in states where same-sex marriage was not legal.  Effective March 27, 2015, the definition of spouse under the Family and Medical Leave Act of 1993  includes employees in a same-sex marriage regardless of state of residence.  Following the Obergefell decision, the Justice Department extended all federal marriage benefits to married same-sex couples nationwide. 
The Federal Government recognizes the marriages of same-sex couples who married in certain states in which same-sex marriage was legal for brief periods between the time a court order allowed such couples to marry and that court order was stayed, including Michigan. The Federal Government also recognized marriages performed in Utah from December 20, 2013 to January 6, 2014, even while the state didn't. Under similar circumstances, the Federal Government never took a position on Indiana or Wisconsin's marriages performed in brief periods, though it did recognize them once the respective states announced they would do so. It had not taken a position with respect to similar marriages in Arkansas  prior to the Obergefell decision legalizing and recognizing same-sex marriages in all 50 states.
Opponents of same-sex marriage have worked to prevent individual states from recognizing same-sex unions by attempting to amend the United States Constitution to define marriage as a union between one man and one woman. In 2006, the Federal Marriage Amendment, which would prohibit states from recognizing same-sex marriages, was approved by the Senate Judiciary Committee on a party-line vote and was debated by the full Senate, but was ultimately defeated in both houses of Congress.  On April 2, 2014, the Alabama State House adopted a resolution calling for a constitutional convention to propose an amendment to ban same-sex marriage nationwide. 
State and territorial recognition
Same-sex marriages are licensed in and recognized by all U.S. states and Washington, D.C., as well as all U.S. territories except American Samoa.  On July 3, 2015, the Attorney General for American Samoa stated "we are reviewing the opinion [ Obergefell v. Hodges ] and its potential applicability to American Samoa, and will provide comment when it is completed."  On January 6, 2016, Alabama's Chief Justice, Roy Moore, issued a ruling forbidding state officials from issuing marriage licenses to same-sex couples.  The ruling had no effect and all Alabama counties continued either issuing marriage licenses to all couples or not issue licenses at all, and in May 2016 Moore was charged with ethics violations by the state Judicial Inquiry Commission for the ruling,  subsequently being suspended from the bench for the remainder of his term on September 30 of that year. 
Counties not issuing marriage licenses
Officials of nine counties in two states, Texas and Alabama, are still unwilling to issue licenses to same-sex couples as of June 2017. Those wishing to marry within the state must travel to another part of the state in order to obtain a license. However, some counties may require at least one person to be a resident of the county in order to receive a marriage license. 
|Issues licenses to opposite-sex couples only||1||0||1|
|Do not issue any marriage licenses||0||8||8|
|Total, by state||1||8||9|
|Percent of state population in said counties||0.006||6.0||0.09|
- Officials of one Texas county, Irion, issue marriage licenses but claim they will refuse same-sex couples. None have applied and no legal action has been taken. 
- Officials in eight Alabama counties no longer issue any marriage licenses.   This is being done in accordance with a state law, which in 1961 was created to preserve racial segregation and made it optional for county clerks to issue marriage licenses. Several have chosen to exercise this option since the Obergefell ruling. 
- Several Kentucky counties initially refused to marry same-sex couples. In response, Kentucky reformed its marriage license forms and removed the name of the county clerk from the licenses. As of June 2016, Chris Hartmann, director of the Kentucky-based Fairness Campaign, said to his knowledge "there are no counties where marriage licenses are being denied" in his state. 
Post- Obergefell, six states have, on occasion, attempted to deny same-sex couples full adoption rights to varying degrees. In Arkansas, Florida, Indiana, and Wisconsin, same-sex couples have been met with rejection when trying to get both parents' names listed on the birth certificate. Alabama's highest court attempted to void an adoption decree obtained by a same-sex couple in Georgia, but the U.S. Supreme Court reversed, restoring joint custody to the adoptive mother on March 7, 2016. Mississippi had once banned same-sex couples from adopting, but the law requiring this was ruled unconstitutional by the United States District Court for the Southern District of Mississippi on March 31, 2016. The ruling was described as having the effect of making same-sex adoption essentially legal in all 50 states.  
On June 26, 2017, the Supreme Court ruled by a 6-3 vote in the case of Pavan v. Smith that under their decision in Obergefell, same-sex couples must be treated equally to opposite-sex couples in the issuance of birth certificates. In December 2016, the Supreme Court of Arkansas upheld a state law only allowing opposite-sex couples to be automatically listed as parents on their children's birth certificates, while prohibiting same-sex couples from being allowed the same on an equal basis. The Supreme Court summarily reversed the Arkansas Supreme Court, finding that the disparity in treatment was a violation of their decision in Obergefell. 
The Supreme Court decision legalizing same-sex marriage in the states and territories did not legalize same-sex marriage on Indian lands. In the United States, Congress (not the federal courts) has legal authority over Indian country. Thus, unless Congress passes a law regarding same-sex marriage on Indian tribes, federally recognized American Indian tribes have the legal right to form their own marriage laws.  As of the time of the Obergefell ruling, 24 tribal jurisdictions legally recognize same-sex marriage. Some tribes have passed legislation specifically addressing same-sex relationships and some specify that state law and jurisdiction govern tribal marriages. As of November 2017, same-sex marriage is legally recognized in 40 tribal jurisdictions.
Local laws prior toObergefell v. Hodges
States and territories that fully licensed/recognized same-sex marriage
Note: This table shows only states that licensed and recognized same-sex marriages or had legalized them, before Obergefell v. Hodges . It does not include states that recognized same-sex marriages from other jurisdictions but did not license them.
|State or territory||Population ||Date of Enactment/Ruling||Date Effective||Legalization method||Details|
|Alaska||736,732||000000002014-10-12-0000 October 12, 2014||000000002014-10-17-0000 October 17, 2014||Federal court decision||U.S. District Court for the District of Alaska ruling in Hamby v. Parnell. |
| ||6,731,484||000000002014-10-17-0000 October 17, 2014||000000002014-10-17-0000 October 17, 2014||Federal court decision||U.S. District Court for the District of Arizona ruling in Connolly v. Jeanes and in Majors v. Horne. |
Same-sex marriage supporters make several arguments in support of their position. Gail Mathabane likens prohibitions on same-sex marriage to past U.S. prohibitions on interracial marriage.  Fernando Espuelas argues that same-sex marriage should be allowed because same-sex marriage extends a civil right to a minority group.  According to an American history scholar, Nancy Cott, "there really is no comparison, because there is nothing that is like marriage except marriage." 
The Human Rights Campaign (HRC) is one of the leading advocacy groups in support of same-sex marriage. According to the HRC's website, "Many same-sex couples want the right to legally marry because they are in love—many, in fact, have spent the last 10, 20 or 50 years with that person—and they want to honor their relationship in the greatest way our society has to offer, by making a public commitment to stand together in good times and bad, through all the joys and challenges family life brings." 
In the United States, such professional organizations as the American Psychiatric Association, American Psychological Association, American Sociological Association, American Anthropological Association, American Medical Association, American Academy of Pediatrics, American Academy of Nursing, and National Association of Social Workers have said that claims that the legal recognition of marriage for same–sex couples undermines the institution of marriage and harms children are inconsistent with the scientific evidence supporting the conclusions: that homosexuality is a normal expression of human sexuality that is not chosen; that gay and lesbian people form stable, committed relationships essentially equivalent to heterosexual relationships; that same-sex parents are no less capable than opposite-sex parents to raise children; that no civilization or viable social order depends on an institution of exclusive heterosexual marriage; and that the children of same-sex parents are no less psychologically healthy and well-adjusted than children of opposite-sex parents.         The body of research strongly supports the conclusion that discrimination by the Federal Government between married same-sex couples and married opposite-sex couples in granting benefits unfairly stigmatizes same-sex couples. The research also contradicts the stereotype-based rationales advanced to support passage of DOMA that the Equal Protection Clause was designed to prohibit. 
The 2012 Democratic Party Platform used the term "marriage equality" in its expression of support. 
Role of social media
Supporters of the legalization of same-sex marriage have successfully used social media websites such as Facebook to help achieve that goal.    Some have argued that the successful use of social media websites by LGBT groups has played a key role in the defeat of religion-based opposition. 
One of the largest scale uses of social media to mobilize support for same-sex marriage preceded and coincided with the arrival at the U.S. Supreme Court of high-profile legal cases for Proposition 8 and the Defense of Marriage Act in March 2013. The "red equals sign" project started by the Human Rights Campaign was an electronic campaign primarily based on Facebook that encouraged users to change their profile images to a red equal sign to express support for same-sex marriage.  At the time of the court hearings, it was estimated that approximately 2.5 million Facebook users changed their profile images to a red equals sign. 
Opponents of same-sex marriage in the United States ground their arguments on parenting concerns, religious concerns, concerns that changes to the definition of marriage would lead to the inclusion of polygamy or incest, natural law-based reasoning, and tradition.  The Southern Baptist Convention adopted a statement in June 2003 that legalizing same-sex relationships would "convey a societal approval of a homosexual lifestyle, which the Bible calls sinful and dangerous both to the individuals involved and to society at large".  The Church of Jesus Christ of Latter-day Saints, the United States Conference of Catholic Bishops, the Southern Baptist Convention, and National Organization for Marriage claim that children do best when raised by a mother and father, and that legalizing same-sex marriage is, therefore, contrary to the best interests of children.     Maggie Gallagher of the National Organization for Marriage has raised concerns about the impact of same-sex marriage upon religious liberty and upon faith-based charities in the United States.  Opponents of same-sex marriage have claimed that redefining marriage to include same-sex relationships would have harmful effects on biological family, children's rights, and social welfare.   Stanley Kurtz of the Weekly Standard has written that same-sex marriage would eventually lead to the legalization of polygamy and polyamory, or group marriage, in the United States. 
The funding of the amendment referendum campaigns has been an issue of great dispute. Both judges   and the IRS  have ruled that it is either questionable or illegal for campaign contributions to be shielded by anonymity. In February 2012, the National Organization for Marriage vowed to spend in Washington legislative races to defeat the Republican state senators who voted for same-sex marriage. 
Politicians and media figures
President Obama's views on same-sex marriage have varied over the course of his political career and become more consistently supportive of same-sex marriage rights over time. In the 1990s, he had supported same-sex marriage while campaigning for the Illinois Senate.   During the 2008 presidential campaign, he said: "I believe that marriage is the union between a man and a woman. For me as a Christian, it is a sacred union. You know, God is in the mix."  He opposed the 2008 California referendum that aimed at reversing a court ruling establishing same-sex marriage there.  In 2009, he opposed two opposing federal legislative proposals that would have banned or established same-sex marriage nationally, stating that each state had to decide the issue.   In December 2010, he expressed support for civil unions with rights equivalent to marriage and for federal recognition of same-sex relationships. He opposed a federal constitutional amendment to ban same-sex marriage.  He also stated that his position on same-sex marriage was "evolving" and that he recognized that civil unions from the perspective of same-sex couples was "not enough". On May 9, 2012, President Obama became the first sitting president to say he believed that same-sex couples should be allowed to marry. He still said the legal question belonged to the states.   In October 2014, Obama told an interviewer that his view had changed: 
Ultimately, I think the Equal Protection Clause does guarantee same-sex marriage in all fifty states. But, as you know, courts have always been strategic. There have been times where the stars were aligned and the Court, like a thunderbolt, issues a ruling like Brown v. Board of Education, but that's pretty rare. And, given the direction of society, for the Court to have allowed the process to play out the way it has may make the shift less controversial and more lasting.
Former presidents Bill Clinton,  Jimmy Carter  and Barack Obama, former vice presidents Dick Cheney,  Al Gore,  Walter Mondale,  and Joe Biden have voiced their support for legal recognition, as have former first ladies Laura Bush,  Hillary Clinton,  Michelle Obama  and Nancy Reagan.  Former president George H. W. Bush and his wife former first lady Barbara Bush have served as witnesses to a same-sex wedding, but neither has publicly stated whether this means they support same-sex marriage in general;  George W. Bush reportedly offered to officiate the same wedding,  but has similarly not made a public statement regarding his position on the issue (as president, he was opposed). Fifteen U.S. senators announced their support in the spring of 2013.  By April 2013, a majority of the Senate had expressed support for same-sex marriage.  Senator Rob Portman of Ohio became the first sitting Republican senator to endorse same-sex marriage in March 2013,  followed by Senator Mark Kirk of Illinois in April,  Lisa Murkowski of Alaska in June,  and Susan Collins of Maine a year later. 
During the 2008 presidential election campaign, Republican vice-presidential candidate Sarah Palin stated: "I have voted along with the vast majority of Alaskans who had the opportunity to vote to amend our Constitution defining marriage as between one man and one woman. I wish on a federal level that that's where we would go because I don't support gay marriage." 
When a U.S. district court invalidated the California referendum that ended same-sex marriages there in 2008, former Speaker of the House Newt Gingrich said it showed "an outrageous disrespect for our Constitution and for the majority of people of the United States who believe marriage is the union of husband and wife".  By the end of 2012, Gingrich was prepared to accept civil—but not religious—same-sex marriages and encouraged the Republican Party to accept the fact of same-sex marriage was certain to become legal in more and more states. 
In an interview on The O'Reilly Factor in August 2010, when Glenn Beck was asked if he "believe(s) that gay marriage is a threat to [this] country in any way", he stated, "No I don't. ... I believe that Thomas Jefferson said: 'If it neither breaks my leg nor picks my pocket what difference is it to me? ' "  
On his radio show in August 2010, commentator Rush Limbaugh said: "Marriage? There's a definition of it, for it. It means something. Marriage is a union of a man and woman. It's always been that. If you want to get married and you're a man, marry a woman. Nobody's stopping you. This is about tearing apart an institution." 
A CNN poll on February 19, 2015 found that 63% of Americans believe gays and lesbians have a constitutional right to marry, up from 49% in August 2010.  In the wake of the Obergefell decision, CNN polling found that 59% of Americans felt the decision was correct. 
A Washington Post / ABC News poll from February–March 2014 found a record high of 59% of Americans approve of same-sex marriage, with only 34% opposed and 7% with no opinion.  In May 2013, a Gallup poll showed that 53% of Americans would vote for a law legalizing same-sex marriage in all 50 states. Three previous readings over the course of a year consistently showed support at 50% or above. Gallup noted: "Just three years ago, support for gay marriage was 44%. The current 53% level of support is essentially double the 27% in Gallup's initial measurement on gay marriage, in 1996."  Some commentators, however, have noted instances where polling data has understated voter opposition to referendums banning same-sex marriage.  One 2010 study concluded that "polls on gay marriage ballot initiatives generally under-estimate the opposition to gay marriage by about seven percentage points". 
As of 2013, public support for same-sex marriage in the United States has solidified above 50%.    Public support for same-sex marriage has grown at an increasing pace since the 1990s.  In 1996, just 25% of Americans supported legalization of same-sex marriage. Polls have shown that support is identical among whites and Hispanics, while support for same-sex marriage trails among blacks.  Polling trends in 2010 and 2011 showed support for same-sex marriage gaining a majority, although the difference is within the error limit of the analysis.  On May 20, 2011, Gallup reported majority support for same-sex marriage for the first time in the country.  In June 2011, two prominent polling organizations released an analysis of the changing trend in public opinion about same-sex marriage in the United States, concluding that "public support for the freedom to marry has increased, at an accelerating rate, with most polls showing that a majority of Americans now support full marriage rights for all Americans."  Gallup's annual Values and Beliefs poll, conducted in May 2017, found that 64% of U.S. adults say same-sex marriages should be recognized by the law as valid, the highest percentage of support recorded to date by the polling firm. 
Effects of same-sex marriage
Economic impact on same-sex couples
Until the Supreme Court's June 2013 ruling in United States v. Windsor required the Federal Government to treat legally married same-sex couples on an equal basis with heterosexual married couples, same-sex married couples faced severe disadvantages. The Federal Government did not recognize those marriages for any purpose. According to a 1997 General Accounting Office study, at least 1,049 U.S. federal laws and regulations include references to marital status. A 2004 study by the Congressional Budget Office found 1,138 statutory provisions "in which marital status is a factor in determining or receiving 'benefits, rights, and privileges. ' "  Many of these laws govern property rights, benefits, and taxation. Same-sex couples whose marriages are not recognized by the federal government are ineligible for spousal and survivor Social Security benefits and are ineligible for the benefits due the spouse of a federal government employee.  One study found that the difference in Social Security income for same-sex couples compared to opposite-sex married couples was per year.
Compared to similarly situated opposite-sex married couples, same-sex couples faced the following financial and legal disadvantages:
- Legal costs associated with obtaining domestic partner documents to gain legal abilities granted automatically by legal marriage, including power of attorney, health care decision-making, and inheritance
- A person can inherit an unlimited amount from a deceased spouse without incurring an estate tax, but is subject to taxes if inheriting from a same-sex partner 
- Same-sex couples were not eligible to file jointly as a married couple and thus could not take the advantages of lower tax rates when the individual income of the partners differs significantly 
- Employer-provided health insurance coverage for a same-sex partner incurred federal income tax 
- Higher health costs associated with lack of insurance and preventative care: 20% of same-sex couples had a member who was uninsured compared to 10% of married opposite-sex couples
- Inability to protect jointly owned home from loss due to costs of potential medical catastrophe
- Inability of a U.S. citizen to sponsor a same-sex spouse for citizenship
Some 7,400 companies were offering spousal benefits to same-sex couples as of 2008. In states that recognized same-sex marriages, same-sex couples could continue to receive those same benefits only if they married. Only 18% of private employers offered domestic partner health care benefits.
Same-sex couples face the same financial constraints of legal marriage as opposite-sex married couples, including the marriage penalty in taxation.  While social service providers usually do not count one partner's assets toward the income means test for welfare and disability assistance for the other partner, a legally married couple's joint assets are normally used in calculating whether a married individual qualifies for assistance. 
Economic impact on the federal government
The 2004 Congressional Budget Office study, working from an assumption "that about 0.6 percent of adults would enter into same-sex marriages if they had the opportunity" (an assumption in which they admitted "significant uncertainty") estimated that legalizing same-sex marriage throughout the United States "would improve the budget's bottom line to a small extent: by less than $1 billion in each of the next 10 years". This result reflects an increase in net government revenues (increased income taxes due to marriage penalties more than offsetting decreased tax revenues arising from postponed estate taxes). Marriage recognition would increase the government expenses for Social Security and Federal Employee Health Benefits but that increase would be more than made up for by decreased expenses for Medicaid, Medicare, and Supplemental Security Income. 
Based in part on research that has been conducted on the adverse effects of stigmatization of gays and lesbians, numerous prominent social science organizations have issued position statements supporting same-sex marriage and opposing discrimination on the basis of sexual orientation; these organizations include the American Psychoanalytic Association and the American Psychological Association. 
Several psychological studies    have shown that an increase in exposure to negative conversations and media messages about same-sex marriage creates a harmful environment for the LGBT population that may affect their health and well-being.
One study surveyed more than 1,500 lesbian, gay and bisexual adults across the nation and found that respondents from the 25 states that have outlawed same-sex marriage had the highest reports of " minority stress "—the chronic social stress that results from minority-group stigmatization—as well as general psychological distress. According to the study, the negative campaigning that comes with a ban is directly responsible for the increased stress. Past research has shown that minority stress is linked to health risks such as risky sexual behavior and substance abuse.
Two other studies examined personal reports from LGBT adults and their families living in Memphis, Tennessee, immediately after a successful 2006 ballot campaign banned same-sex marriage. Most respondents reported feeling alienated from their communities. The studies also found that families experienced a kind of secondary minority stress, says Jennifer Arm, a counseling graduate student at the University of Memphis. 
At the Perry v. Schwarzenegger trial, expert witness Ilan Meyer testified that the mental health outcomes for gays and lesbians would improve if laws such as Proposition 8 did not exist because "when people are exposed to more stress...they are more likely to get sick..." and that particular situation is consistent with laws that say to gay people "you are not welcome here, your relationships are not valued." Such laws have "significant power", he said. 
In 2009, a pair of economists at Emory University tied the passage of state bans on same-sex marriage in the US to an increase in the rates of HIV infection.   The study linked the passage of same-sex marriage ban in a state to an increase in the annual HIV rate within that state of roughly 4 cases per 100,000 population.
A study by the Columbia Mailman School of Public Health found that gay men in Massachusetts visited health clinics significantly less often following the legalization of same-sex marriage in that state. 
There is no complete data on the number of same-sex marriages conducted in the United States. Some states and counties record the number of marriages, but the Federal Government does not. Nevertheless, in August 2016, the Treasury Department published a research paper, in which it had linked the tax returns of same-sex couples who had filed jointly in 2014 with their Social Security records. This way, it was able to determine the number of same-sex marriages in the United States. Additionally, the Treasury estimated that about 97.5% of all married couples file their taxes jointly. The statistics showed that in 2014 there was an estimated 183,280 married same-sex couples.
According to the statistics, female couples were four times more likely to have adopted children, than male couples. Additionally, male couples earned a pretax average of $176,000 per year, while lesbian couples earned $124,000 and straight couples earned $113,000. Most female same-sex marriages were celebrated in Oakland, Seattle, San Francisco, Springfield (MA) and Long Beach, compared to San Francisco, New York City, Washington D.C., Palm Springs and Seattle for gay male marriages. 
United States case law regarding same-sex marriage:
- Anonymous v. Anonymous, 67 Misc.2d 982 (N.Y. 1971). The law makes no provision for a "marriage" between persons of the same sex.
- Baker v. Nelson, 191 N.W.2d 185 (Minn. 1971). Upholds a Minnesota law defining marriage as the union of a man and a woman. (Overruled by Obergefell v. Hodges in 2015; see below)
- Jones v. Hallahan, 501 S.W.2d 588 (Ky. 1973). Upholds the denial of a marriage license to two women in Kentucky based on dictionary definitions of marriage, despite the fact that state statutes do not specify the gender of marriage partners. 
- Frances B. v. Mark B., 78 Misc.2d 112 (1974). Marriage is and always has been a contract between a man and a woman.
- Singer v. Hara, 522 P.2d 1187 (Wash. Ct. App. 1974). The historical definition of marriage is between one man and one woman, and same-sex couples are inherently ineligible to marry. This ban does not constitute sex discrimination.
- Adams v. Howerton, 673 F.2d 1036 (9th Cir. 1982), cert. denied, 458 U.S. 1111. A same-sex marriage does not make one a "spouse" under the Immigration and Nationality Act.
- De Santo v. Barnsley, 476 A.2d 952 (Pa. Super. Ct. 1984). Same-sex couples can not divorce because they cannot form a common law marriage. 
- In re Estate of Cooper, 149 Misc.2d 282 (Sur. Ct. Kings Co. 1990). The state has a compelling interest in fostering the traditional institution of marriage and prohibiting same-sex marriage.
- Baehr v. Lewin, 852 P.2d 44 (Haw. 1993). A statute limiting marriage to opposite-sex couples violates the Hawaii constitution's equal-protection clause unless the state can show that the statute is both justified by compelling state interests and also narrowly tailored. This ruling prompted the adoption of Hawaii's constitutional amendment allowing the Legislature to restrict marriage to different-sex couples and the federal Defense of Marriage Act.
- Dean v. District of Columbia, 653 A.2d 307 (D.C. 1995). DC does not authorise same-sex marriage; denial of a marriage license does not violate the Due Process Clause of the United States Constitution.
- Storrs v. Holcomb, 645 N.Y.S.2d 286 (App. Div. 1996). New York does not recognize or authorize same-sex marriage. Overturned in part by Martinez v. County of Monroe in 2008.
- In re Estate of Hall, 707 N.E.2d 201, 206 (Ill. App. Ct. 1998). Illinois does not recognize a same-sex marriage. The petitioner's claim to be in a same-sex marriage was not in a marriage recognized by law.
- Baker v. Vermont, 170 Vt. 194; 744 A.2d 864 (Vt. 1999). The Common Benefits Clause of the state constitution requires that same-sex couples be granted the same legal rights as married persons, though it need not be called marriage.
- Frandsen v. County of Brevard, 828 So. 2d 757 (Fla. 2001). The Florida Constitution will not be construed to recognize same-sex marriage; sex classifications not subject to strict scrutiny under the Florida constitution.
- Burns v. Burns, 560 S.E.2d 47 (Ga. Ct. App. 2002). Marriage is the union of one man and one woman.
- In re Estate of Gardiner, 42 P.3d 120 (Kan. 2002). A post-operative male-to-female transsexual is not a woman within the meaning of the statutes and cannot validly marry another man.
- Rosengarten v. Downes, 806 A.2d 1066 (Conn. Ct. App. 2002). Connecticut will not dissolve a Vermont civil union.
- Standhardt v. Superior Court ex rel. County of Maricopa, 77 P.3d 451 (Ariz. Ct. App. 2003) The Constitution of Arizona does not provide the right to same-sex marriage.
- Goodridge v. Dept. of Public Health, 798 N.E.2d 941 (Mass. 2003). The denial of marriage licenses to same-sex couples violated provisions of the Massachusetts State Constitution guaranteeing individual liberty and equality, and it was not rationally related to a legitimate state interest.
- Morrison v. Sadler, 821 N.E.2d 15 (Ind. Super. Ct. 2005). Indiana's Defense of Marriage Act is valid.
- Langan v. St. Vincent's Hospital, 802 N.Y.S.2d 476 (App. Div. 2005). For the purposes of New York's wrongful death statute, the survivor partner from a Vermont civil union lacks standing as a "spouse".
- Citizens for Equal Protection v. Bruning, 455 F.3d 859 (8th Cir. 2006). Nebraska's Initiative Measure 416 does not violate Fourteenth Amendment's Equal Protection Clause, was not a bill of attainder, and does not violate the First Amendment. 
- Lewis v. Harris, 908 A.2d 196 (N.J. 2006). Prohibiting same-sex marriage does not violate the New Jersey Constitution, but the state must extend all the rights and responsibilities of marriage to same-sex couples. The Legislature had 180 days to amend the marriage laws or create a "parallel structure".
- Andersen v. King County, 138 P.3d 963 (Wash. 2006). Washington's Defense of Marriage Act does not violate the State Constitution.
- Hernandez v. Robles, 855 N.E.2d 1 (N.Y. 2006). The New York State Constitution does not require that marriage rights be extended to same-sex couples. 
- Conaway v. Deane, 932 A.2d 571 (Md. 2007). Upholds a Maryland law defining marriage as the union of a man and a woman.
- Martinez v. County of Monroe, 850 N.Y.S.2d 740 (App. Div. 2008). Because New York recognizes the marriages of opposite-sex couples from other jurisdictions, it must do the same for same-sex couples. 
- In re Marriage Cases, 183 P.3d 384 (Cal. 2008). Limiting marriage to opposite-sex couples is invalid under the equal protection clause of the California Constitution. Full marriage rights, not merely domestic partnership, must be offered to same-sex couples. 
- Kerrigan v. Commissioner of Public Health 957 A.2d 407 (Conn. 2008). The availability of civil unions but not marriage to same-sex partners is a violation of the equality and liberty provisions of the Connecticut Constitution.
- Strauss v. Horton, 207 P.3d 48 (Cal. 2009). Proposition 8 was validly adopted, and marriages contracted before its adoption remain valid. 
- Varnum v. Brien, 763 N.W.2d 862 (Iowa 2009). Barring same-sex couples from marriage violates the equal protection provisions of the Iowa Constitution. Equal protection requires full marriage, rather than civil unions or some other substitute, for same-sex couples.
- Challenges to DOMA Section 3
- Gill v. Office of Personnel Management (2009–2013). Section 3 of the federal Defense of Marriage Act is found unconstitutional in U.S. district court. The First Circuit Court of Appeals affirms that ruling and stays implementation pending appeal. Windsor finds Section 3 unconstitutional and appeal of Gill is denied by the Supreme Court.
- Massachusetts v. United States Department of Health and Human Services (2009–2013). Decided alongside Gill with the same outcome.
- Golinski v. Office of Personnel Management (2010–2013). Section 3 of the federal Defense of Marriage Act is found unconstitutional in U.S. district court, which determines that sexual orientation is a quasi-suspect classification requiring the court to apply intermediate scrutiny, that is, to determine whether Section 3 relates to an important government interest. On appeal the case is held in abeyance pending the decision of the U.S. Supreme Court in Windsor, which settles the issues raised in Golinski, the appeal of which to the Supreme Court is then denied.
- United States v. Windsor (2010–2013). Section 3 of the federal Defense of Marriage Act is found unconstitutional in U.S. district court. The Second Circuit Court of Appeals affirms that ruling, as does the U.S. Supreme Court. The U.S. Government began implementing the decision the same week.
- California Proposition 8
- Hollingsworth v. Perry (2009–2013). California's Proposition 8, a voter-endorsed constitutional amendment banning same-sex marriage, is found unconstitutional in U.S. district court in Perry v. Schwarzenegger. The proposition's backers appeal to the Ninth Circuit Court of Appeals, which upholds the district court's finding of unconstitutionality in Perry v. Brown. The U.S. Supreme Court ruled that the proposition's backers lacked standing to appeal and left the district court ruling intact. 
- Same-sex marriage rights
- Christiansen v. Christiansen. On June 6, 2011, the Supreme Court of Wyoming grants a divorce to two women who married in Canada, but says its decision does not apply "in any context other than divorce". 
- Port v. Cowan (2010–2012). Maryland must recognize valid out-of-state same-sex marriages under doctrine of comity. 
- Garden State Equality v. Dow (2011–2013), New Jersey's civil unions violate due process guarantees; denying same-sex marriage ruled unconstitutional in state superior court. The N.J. Supreme Court refuses to stay the ruling and the state defendants drop their appeal.
- Griego v. Oliver, 316 P.3d 865 (N.M. 2013). The New Mexico Supreme Court rules that the State Constitution requires marriage rights to be extended to same-sex couples.
- Kitchen v. Herbert (Utah). U.S. district court, 961 F. Supp. 2d 1181 (2013), rules the state's ban on same-sex marriage is unconstitutional. The Tenth Circuit Court of Appeals upholds that ruling upheld on June 25, 2014. All parties support review by the U.S. Supreme Court, and that court denied review on October 6. 
- Whitewood v. Wolf (Pennsylvania). On May 20, 2014, Judge John E. Jones III rules that Pennsylvania's same-sex marriage ban is unconstitutional.
- Geiger v. Kitzhaber and Rummell v. Kitzhaber (Oregon). On May 19, 2014, District Judge Michael J. McShane declares Oregon's same-sex marriage ban unconstitutional.
- Bostic v. Schaefer (Virginia). The Fourth Circuit on July 28, 2014, in a 2–1 decision, affirms a district court ruling that Virginia's denial of marriage rights to same-sex couples is unconstitutional. The Supreme Court denied review on October 6. 
- Baskin v. Bogan (Indiana) and Wolf v. Walker (Wisconsin). The Seventh Circuit consolidated these cases and on September 4, 2014, upheld two district court rulings that had found Indiana's and Wisconsin's bans on same-sex marriage unconstitutional. The U.S. Supreme Court denied review on October 6. 
- Bishop v. Smith (Oklahoma). On July 18, 2014, the Tenth Circuit upholds the district court ruling that Oklahoma's ban on same-sex marriage is unconstitutional. The Supreme Court denied review on October 6. 
- Barrier v. Vasterling (Missouri). State Circuit Judge J. Dale Youngs rules on October 3, 2014, that Missouri's refusal to recognize same-sex marriages from other jurisdictions violates the plaintiff same-sex couples' right to equal protection under both the state and federal constitutions.
- Caspar v. Snyder (Michigan). On January 15, 2015, U.S. District Judge Mark A. Goldsmith ruled that the state must recognize the validity of "window marriages" established on March 21 and 22, 2014, before the Sixth Circuit Court of Appeals stayed a district court ruling in DeBoer v. Snyder that found Michigan's ban on same-sex marriage unconstitutional, despite the fact that DeBoer was later reversed. The state chose not to appeal.
- Obergefell v. Hodges (2013-2015) U.S. Supreme Court case finding state bans on same-sex marriage to be unconstitutional under the 14th Amendment. (Overturned Baker v. Nelson)
- Same-sex marriage
- Status of same-sex marriage
- Timeline of same-sex marriage
- Timeline of same-sex marriage in the United States
- History of same-sex marriage in the United States
- Public opinion of same-sex marriage in the United States
- Same-sex marriage under United States tribal jurisdictions
- Same-sex unions and military policy#United States
- LGBT employment discrimination in the United States
- Rights and responsibilities of marriages in the United States
- LGBT rights in the United States
- Defense of Marriage Act
- Federal Marriage Amendment
- Former U.S. state constitutional amendments banning same-sex unions
- Same-sex marriage legislation in the United States
- Same-sex marriage law in the United States by state
- Same-sex marriage status in the United States by state
- Same-sex unions in the United States
- Domestic partnership in the United States
- The rulings striking down same-sex marriage bans are from U.S. district courts in the following states: Utah,Oklahoma,Virginia,Texas,Michigan,Idaho,Oregon, Pennsylvania,South Dakota,Wisconsin, Indiana,Kentucky,Colorado,Florida,North Carolina,Alaska, Arizona, Wyoming, Kansas, Missouri, West Virginia,South Carolina,Montana,Arkansas, Mississippi, South Dakota, and Alabama.
- The cases (and states) are:Wright v. Arkansas(Arkansas),In re Marriage of J.B. and H.B.andIn the Matter of the Marriage of A.L.F.L. and K.L.L.(Texas),Brinkman v. Long(Colorado),Pareto v. RuvinandHuntsman v. Heavilin(Florida),In Re Costanza and Brewer(Louisiana), andState v. Florida(Missouri).
- Barrier v. Vasterling, Missouri Circuit Court, 16th Judicial Circuit
- Robicheaux v. Caldwell(Louisiana),Conde v. Rius(Puerto Rico)
- Borman v. Pyles-Borman(Tennessee)
- The cases reversed (and affected states) are:Bourke v. BeshearandLove v. Beshear( Kentucky),DeBoer v. Snyder( Michigan),Obergefell v. HimesandHenry v. Himes( Ohio), andTanco v. Haslam( Tennessee).
- Among many examples: (1) the U.S. District Court ruling inBourke v. Beshear, which required Kentucky to recognize same-sex marriages from Canada and several U.S. states, was decided on equal protection grounds alone. The plaintiffs claimed that Kentucky's ban violated the full faith and credit clause, but the court found it unnecessary to address that argument.and (2) the plaintiffs inRobicheaux v. Caldwell, who sought Louisiana's recognition of their out-of-state marriages, argued only on the basis of equal protection and due process. One of the Louisiana statutes they challenged made clear the state's assertion of its right to deny recognition to the legal act of another state: "A purported marriage between persons of the same sex violates astrong public policyof the state of Louisiana". (emphasis added)
- Other cases that sought review by the U.S. Supreme Court wereGolinski v. Office of Personnel Management,Gill v. Office of Personnel Management,Massachusetts v. United States Department of Health and Human Services, andPedersen v. Office of Personnel Management.
- In early 2013 the IRS recognized the community property and income of same-sex partners in community property states.