OMAHA, Neb. (AP) — Seven same-sex Nebraska couples have filed a lawsuit to have their marriages recognized.

The American Civil Liberties Union of Nebraska announced Monday that the couples have challenged the state's constitutional ban in federal court.

The plaintiffs include Susan and Sally Waters of Omaha, who have been together for 17 years and were married in California before moving to Nebraska. Sally Waters was diagnosed with terminal breast cancer last year. She says without formal recognition of their marriage, her spouse won't receive the same tax and Social Security benefits to take care of the couple's children.

Top state officials say they will fight the lawsuit.