A judge has opened the way for the nation's most populous state to follow Massachusetts in allowing same-sex couples to tie the knot, but both sides in the debate predicted a vigorous court fight first. San Francisco County Superior Court Judge Richard Kramer ruled Monday that while withholding marriage licenses from gays and lesbians has been the status quo, it constitutes discrimination the state can no longer justify. "The state's protracted denial of equal protection cannot be justified simply because such constitutional violation has become traditional," Kramer wrote. "Simply put, same-sex marriage cannot be prohibited solely because California has always done so before."Ushering out a social norm long considered sacred won't happen right away, however. Kramer's decision is stayed automatically for 60 days to allow time for appeals, and conservative groups that oppose same-sex marriages vowed to uphold California's one woman-one man marriage laws.