The oral arguments in a pivotal same-sex marriage case, filed in 2005 by six same-sex Iowa couples, will be heard by the Iowa Supreme Court on Tuesday. The lawsuit - which pits gay rights' supporters against those who argue that 'gay marriage' threatens traditional family values - could either become a national victory for the gay rights movement or a chance to reinforce Iowa's decade-old gay marriage ban.

Last year, Polk County District Court Judge Robert Hanson declared the same-sex marriage ban unconstitutional and ignited a legal fire storm. Later, Hanson suspended his ruling, with same-sex marriage opponents saying the case belongs in the Iowa Legislature, not the courts. And, now, the Iowa Supreme Court decides the case.

The lawsuit - Varnum vs. Brien - arose from six same-sex couples who were denied marriage licenses by the Polk County recorder, Timothy Brien. Among the principals in the case are Kate Varnum and Trish Varnum.

The couples have been financed by a national gay and lesbian rights group, Lambda Legal. Camilla Taylor, senior legal counsel for the group, said the couples who filed the lawsuit are optimistic they will prevail. She noted that the Iowa high court has traditionally led the nation on civil rights issues.

The ruling in this case could make Iowa the first state in the Midwest to legalize same-sex marriage. Other high-court decisions that favor gay rights advocates have come from traditionally liberal coastal states, including California, Massachusetts and Connecticut.

According to Angela Onwuachi-Willig, University of Iowa law professor, who has signed a court brief supporting gay-marriage rights, "This is the heartland of America - a place where family values are revered. It would be an incredibly strong signal for the Iowa Supreme Court to find that same-sex marriages are legal."