gay_cityhall_gavel.jpgA federal judge in San Francisco is scheduled to rule Wednesday on whether Proposition 8, California’s voter-approved ban on same-sex marriage, violates the U.S. Constitution.

The case before U.S. District Judge Vaughn Walker has been the nation’s first federal trial on a U.S. constitutional challenge to a state law prohibiting gay marriage.

A previous five-year battle over same-sex marriage in California centered on the state rather than federal constitution.

The federal trial pits two same-sex couples who want to marry against the sponsors of Proposition 8 and their campaign committee, ProtectMarriage.com.

The measure was enacted as a state constitutional amendment by California voters in 2008 and provides that “only marriage between a man and a woman is valid or recognized in California.”

Walker heard evidence in the nonjury trial in January, presided over closing arguments in June and, according to a court spokeswoman, will file a decision between 1 p.m. and 3 p.m. Wednesday.

Both sides have said Walker’s court is only the first stop and that they will appeal if they lose, first to a federal appeals court in San Francisco and then likely to the U.S. Supreme Court.

In fact Proposition 8’s sponsors filed a motion late Tuesday asking him to stay his ruling if he decides to strike down the ban while they appeal to the 9th U.S. Circuit Court of Appeals.

Proposition 8 attorney Charles Cooper argued in the filing that the sponsors are likely to win on appeal and that allowing same-sex marriage in the interim would cause confusion and uncertainty.

Cooper wrote, “Another purported window of same-sex marriage in California would cause irreparable harm.”

The last window of same-sex marriage in the state occurred between June 2008, when a California Supreme Court ruling allowing gay weddings under the state Constitution went into effect, and Nov. 4, 2008, when voters approved Proposition 8.

About 18,000 same-sex couples married during that time, and the state high court left those marriages in place at the same time that it upheld voters’ right to enact Proposition 8 in a decision in May 2009.

The two couples who challenged California’s same-sex marriage ban in federal court last year, Kris Perry and Sandy Stier of Berkeley and Paul Katami and Jeff Zarrillo of Burbank, claim the measure violates their right to equal treatment and their fundamental right to marry.

Another, narrower argument by the plaintiffs that would apply only to California is that California has a uniquely unequal situation because some same-sex couples are married while others cannot marry.

The initiative’s sponsors contend it is constitutional because it is a reasonable way of preserving the traditional definition of marriage and promoting the welfare of children.

There will be no court hearing when Walker issues the ruling. The decision will be posted on the court’s website at www.cand.uscourts.gov, and a limited number of paper copies will be available at the court clerk’s offices in San Francisco, Oakland and San Jose.

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