WASHINGTON (AP) - The Obama administration asked the Supreme Court on Thursday to overturn California's ban on same-sex marriage and take a skeptical view of similar bans elsewhere, making a historic argument for gay rights.
The Obama administration's friend-of-the-court brief marked the first time a US president has urged the high court to expand the right of gays and lesbians to wed.
The filing unequivocally calls on the justices to strike down a 2008 ballot measure that barred gays and lesbians from wedding in California.
It does not explicitly call for marriage equality across the United States but points the court in that direction.
The administration's position, if adopted by the court, probably would result in gay marriage becoming legal in seven other states that, like California, give gay couples all the benefits of marriage, but don't allow them to wed.
They are: Delaware, Hawaii, Illinois, Nevada, New Jersey, Oregon and Rhode Island.
The brief marks President Barack Obama's most expansive view of the legal rights of gays and lesbians to marry. He announced his personal support for gay marriage last year but has said the issue should be governed by states.
The denial of marriage to same-sex couples, "particularly where California at the same time grants same-sex partners all the substantive rights of marriage, violates equal protection," the administration said.
In the longer term, the administration urges the justices to subject laws that discriminate on sexual orientation to more rigorous review than usual, a standard that would imperil other state bans on same-sex marriage.
Obama, a former constitutional law professor, raised expectations that he would back a broad brief during his inauguration address on Jan. 21.
He said the nation's journey "is not complete until our gay brothers and sisters are treated like anyone else under the law." "For if we are truly created equal, than surely the love we commit to one another must be equal as well," Obama said.
Obama has a complicated history on gay marriage.
As a presidential candidate in 2008, he opposed the California ban but didn't endorse gay marriage.
He later said his personal views on gay marriage were "evolving."
When he ran for re-election last year, Obama announced his personal support for same-sex marriage, but said marriage was an issue that states, not the federal government, should decide.
American public opinion has shifted in support of gay marriage in recent years.
In May 2008, Gallup found that 56 percent of Americans felt same-sex marriages should not be recognised by the law as valid. By last November, 53 percent felt they should be legally recognised.
The Justice Department planned to submit its brief later Thursday, the deadline for filing in the California case. The justices will hear oral arguments in the case on March 26.
The Proposition 8 ballot initiative was approved by California voters in 2008 in response to a state Supreme Court decision that had allowed gay marriage.
Twenty-nine other states have constitutional amendments banning gay marriage; nine states and the Washington federal district recognise same-sex marriage.
In recent days, many states, organisations and individuals have filed briefs in the case.
Thirteen states, including four that do not now permit gay couples to wed, urged the court on Thursday to declare the ban unconstitutional. They said marriage enhances economic security and emotional well-being for the partners, and is better for children.
"All of these interests are furthered by ending the exclusion of same-sex couples from the institution," said the brief signed by Massachusetts Attorney General Martha Coakley.
It was joined by Connecticut, Iowa, Maine, Maryland, New Hampshire, New York, Vermont, Washington, Delaware, Illinois, New Mexico, Oregon and the District of Columbia.
More than 100 prominent Republicans have signed a friend-of-the-court brief in support of gay marriage. Among them are former presidential candidate Jon Huntsman and Florida Rep. Ileana Ros-Lehtinen.
One day after the Supreme Court hears the Proposition 8 case, the justices will hear arguments on another gay marriage case, this one involving provisions of the federal Defense of Marriage Act.
That act defines marriage as between a man and a woman for the purpose of deciding who can receive a range of federal benefits.
The administration abandoned its defense of the act in 2011, but the measure will continue to be federal law unless it is struck down or repealed.
In a brief filed last week, the government said Section 3 of the act "violates the fundamental constitutional guarantee of equal protection" because it denies legally married same-sex couples many federal benefits that are available only to legally married heterosexual couples.