Former President Bill Clinton chimed in, too, writing that he now regretted his decision to sign the Defense of Marriage Act in 1996 and urging that it be struck down. President Barack Obama's administration also asked that DOMA be declared unconstitutional and that Proposition 8 be struck down.
For gay-marriage opponents, it's been an occasionally daunting period as they watch a steady stream of prominent politicians and institutions join the rival side.
The conservative American Family Association's website, for example, listed some of the many well-known corporations that are now supporting same-sex marriage — including Google, Microsoft, Citigroup, Apple, Nike, Facebook and Starbucks. The website suggests that Americans opposed to gay marriage should boycott these companies, but the president of the Mississippi-based association, Tim Wildmon, acknowledges that would be impractical.
"There's too many of them to effectively boycott," he said in a telephone interview.
Wildmon expects the U.S. to remain divided over gay marriage for a long time and hopes neither Congress nor the courts try to interfere with the right of states to set their own policies.
"That's just the way it's going to be," he said. "If you want to be a homosexual married couple, move to a state that accepts it."
Such interstate moves could indeed occur, but with a potential cost for the states being forsaken, said gay rights lawyer Jon Davidson of Lambda Legal. "Maybe that's what some states want, but the outpouring of business support for us indicates a lot of businesses don't want that to happen," he said. "It creates all sorts of problems."
Among some conservatives, there's been frustration at the frequent exhortation from gay-rights activists that the Supreme Court should be "on the right side of history" by endorsing same-sex marriage.
"It requires no courage, at this point in history, to side with gay marriage advocates," Maggie Gallagher, a co-founder of the National Organization for Marriage, wrote in a commentary. "Respecting the rights of the millions of Americans who disagree, and respecting the boundaries of our Constitution, is staying on the right side of history."
Conservative radio commentator Rush Limbaugh, on his show Wednesday, suggested the spread of same-sex marriage was indeed inevitable. He cited signs of increasing divisions among Republicans on the issue.
"Whether it happens now at the Supreme Court or somehow later, it is going to happen," Limbaugh said. "It's just the direction the culture is heading. ... The opposition that you would suspect exists is in the process of crumbling on it."
In any case, it's unlikely that some of the most conservative states — those that adopted gay-marriage bans by overwhelming margins — will recognize same-sex marriages unless forced to by the courts.
A likely result is a steady stream of state-level lawsuits by gay couples, according to Boston-based lawyer Mary Bonauto, whose work with Gay and Lesbian Advocates and Defenders helped legalize same-sex marriage in several New England states.
"There are committed gay couples in every state who want to stand up and make that legal commitment to marriage," Bonauto said. "They're not going to go away. ... They believe our national promise of equal protection under the law applies to them, too, not just to the East and West coasts and Iowa."
Depending on how such lawsuits fare, Bonauto said, "I think this issue could be back at the Supreme Court in a number of years."
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