Same-sex couples Paul Katami (L), Jeff Zarillo (2nd L), and Kris Perry (2nd R) and Sandy Stier pose for photographs before the start of their trial in San Francisco, California January 11, 2010. California's ban on gay marriage goes to trial on Monday in a federal case that plaintiffs hope to take all the way to the US Supreme Court and overturn bans throughout the nation. Two Californian men challenging a ban on same-sex marriage on Monday said they had been a couple for nine years and felt like third-class citizens, leading them to launch the federal case which could set a national precedent. The men and a lesbian couple unable to marry in California hope to take their case against the state' s Proposition 8 ban on same-sex marriage all the way to the US Supreme Court and to overturn bans throughout the nation. A loss in the top court, two ranks above the action in the case which began on Monday, would seriously undermine efforts to win gay marriage rights in state courts. The United States is divided on same-sex marriage. It is legal in only five states, though most of those, and the District of Columbia, approved it last year. Approval of Prop 8 in November 2008 was a sweet victory for social conservatives in a state with a liberal, trend-setting reputation, and maintained the steady success they have scored on the issue at the ballot box. Where it is legal, gay marriage has been championed by courts and legislatures, not voters. 'I don't think of myself as a bad person,' said Paul Katami, describing the persecution he felt from a media campaign warning California parents to 'protect' their children by voting against same-sex unions in the 2008 poll. He and his would-be husband, Jeffrey Zarrillo, described slights in gay life that ranged from being pelted with rocks and eggs in college to the awkwardness of checking into a hotel and not being able to clarify the relationship. 'Being able to call him my husband is so definitive,' Katami said. 'There is no subtlety to it. It is absolute. ' Gays and lesbians have nearly equal rights under domestic partnership laws, but the two men said that left them feeling second-or third-class citizens and they wanted to be married to have kids. 'We hear a lot of 'What's the big deal?' The big deal is creating a separate category for us,' Katami said. Gay rights lawyers in the case describe their battle as a continuation of the fight against racist laws stopping whites and blacks from marrying. Marriage is a fundamental constitutional right, and in addition gays and lesbians deserve special protection from discrimination, they say. What is current situation of the nation on same-sex union?