SAN FRANCISCO (Reuters) - The U.S. judge weighing the constitutionality of gay marriage in a San Francisco courtroom on Wednesday will ask how weddings between gays and lesbians could undermine marriage between men and women.
The case to overturn California's ban on gay marriage, approved by voters in 2008, is based on the argument that it denies equal rights to same-sex couples. But it may turn on whether voters had a legitimate, reasonable reason for their decision or were motivated by discrimination.
Closing arguments will be held on Wednesday in the case, which began on Jan. 11, and is likely to be appealed all the way to the U.S. Supreme Court.
District Court Chief Judge Vaughn Walker set the agenda for closing arguments with a long list of questions including whether there was a good reason, or rational basis, to maintain marriage exclusively for opposite-sex couples.
"Voters' unfounded and discriminatory stereotypes are not a substitute for proof that a law actually furthers a legitimate state interest," wrote gay rights lawyers Ted Olson and David Boies, who faced off in the 2000 Supreme Court decision that put George Bush in the White House.
They argue that same-sex couples who marry grow healthier and wealthier, their children are better of, and the state benefits from the expanded definition of marriage.
Opposite-sex marriage are not affected at all and the California constitutional amendment limiting marriage to a man and a woman -- similar to provisions in the vast majority of U.S. states -- is based in moral indignation and hate, they conclude.
Charles Cooper, the chief lawyer defending the ban known as Prop 8, argues that gay marriage would, or at least reasonably could, weaken the institution of marriage by robbing it of "special encouragement" to stay together and raise children.
"These changes are likely to reduce the willingness of biological parents, especially fathers, to make the commitments and sacrifices necessary to marry, stay married, and play an active role in raising their children," Cooper wrote.
A ruling in the case is expected within weeks.
Reporting by Peter Henderson