The Arkansas chapter of the American Civil Liberties Union filed the lawsuit on behalf of the families in Pulaski County Circuit Court seeking to overturn Act 1, which was approved by voters in last month's general election.

"Act 1 violates the state's legal duty to place the best interest of children above all else," said Marie-Bernarde Miller, a Little Rock attorney in the lawsuit.

The group filed the lawsuit on behalf of 29 adults and children from more than a dozen families, including a grandmother who lives with her same-sex partner of nine years and is the only relative able and willing to adopt her grandchild, who is now in Arkansas state care.

The plaintiffs also include Stephanie Huffman and Wendy Rickman, a lesbian couple raising two sons together who want to adopt a foster child from the state.