Snap Analysis: Gay marriage fight headed to Supreme Court?

LOS ANGELES (Reuters) - A federal judge's ruling on Wednesday overturning California's ban on same-sex marriage delivered a key victory to gay rights activists in a fight that may ultimately be decided by the U.S. Supreme Court.

U.S. District Judge Vaughn Walker's decision, which found banning gay marriage unconstitutional and follows a three-week trial in January, will almost certainly be appealed by the defendants to the 9th Circuit Court of Appeals in San Francisco.

The loser of that ruling is expected to quickly appeal again, eventually sending the incendiary issue of gay marriage -- which is currently subject to a patchwork of laws in U.S. states -- to the nation's highest court.

* In striking down Proposition 8 banning same-sex marriage, which was approved by about 52 percent of California voters in 2008, Walker gives supporters of gay rights momentum. "Equality won!," said talk show host and comedian Ellen DeGeneres, who lives in California and is married to a woman, in a Twitter update after the ruling.

* The next stop in the legal fight will likely be the 9th Circuit, which is widely considered one of the nation's more liberal federal appeals courts.

At the Supreme Court, should the case get that far, supporters of gay marriage hope they can eventually convince Supreme Court Justice Anthony Kennedy, the swing vote on that court, to side with them.

* Other challenges to anti-gay marriage laws are under way across the country, which has proven sharply divided on the issue, and could arrive at the Supreme Court at the same time.

In Massachusetts, a judge recently struck down the Defense of Marriage Act, which defines marriage as the union of one man and one woman under U.S. law.

Same sex marriage is currently legal in Massachusetts, Connecticut, Iowa, Vermont, New Hampshire and Washington, D.C.

* Winners in Wednesday's ruling include the trailblazing San Francisco city, which first handed out marriage licenses to gays in 2004 and the odd couple pairing of lawyers who fought for the plaintiffs: Republican Theodore Olson and Democrat David Boies.

Losers include those who backed Proposition 8, arguing that allowing gays to legally wed would undermine marriages between men and women, which they say should be primarily geared toward having and raising children.

Among those who poured money and organizational effort into the campaign supporting Proposition 8 was the Mormon church.

*Americans oppose gay marriage by a 57 to 40 percent margin, according to a 2009 Gallup poll. Age is also a factor: Among 18-29-year olds, 59 percent think it should be legal, while 66 percent of those over 65 think it should be banned, Gallup found.

President Barack Obama has said that he opposes legalizing gay marriage.

* In July, Argentina became the first South American country to legalize same-sex marriage. A few other countries around the world permit it, including the Netherlands, Sweden, Portugal and Canada.

(Editing by Cynthia Osterman)