Oklahoma, where gay marriage comes sweepin' down the plain. On Tuesday, a federal judge ruled the state's ban on same-sex marriage is a violation of the U.S. Constitution after two gay couples sued. In 2004, the state added a constitutional amendment defining marriage as between one man and one woman. Yesterday, the judge wrote that this measure violates the country's equal protection laws. Same-sex marriage won't yet be allowed—the ruling was stayed pending appeals.