SAN FRANCISCO (AP) - Deciding one of the few lawsuits arguing the case for gay marriage in federal court, a California judge on Thursday ruled that a 1996 law recognizing only unions between a man and a woman as valid does not violate the U.S. Constitution. But U.S. District Judge Gary Taylor also declined to rule on whether a state ban on same-sex marriage violates the civil rights of a gay Southern California couple while a separate legal challenge to California's laws works its way through the state courts. "The question of the constitutionality of California's statutory prohibition on same-sex...