Four lesbian couples on Wednesday filed a federal lawsuit challenging the constitutionality of Mississippi's law banning adoption by same-sex couples.

Mississippi is the only state left with an outright adoption ban based solely on sexual orientation.

Plaintiffs in the case are Kari Lunsford and Tinora Sweeten-Lunsford, who are seeking to adopt a child; Brittany Rowell and Jessica Harbuck, also seeking to adopt; Donna Phillips and Janet Smith, parents to a young daughter; and Kathryn Garner and Susan Hrostowski, who have a 15-year-old son.

Representing the couples are Roberta Kaplan of Paul, Weiss, Rifkind, Wharton & Garrison LLP and Robert McDuff of McDuff & Byrd, the same legal team behind the federal case that struck down Mississippi's ban on gay marriage. Kaplan in 2013 argued the Supreme Court case that struck down a key provision of the Defense of Marriage Act (DOMA), which led to the federal government recognizing the marriages of gay and lesbian couples.

“Mississippi's ban on adoption by gay and lesbian couples blatantly discriminates against loving families, unfairly harms innocent children, and plainly cannot be reconciled with the constitutional guarantees of due process and equal protection as recently interpreted by the Supreme Court,” said Kaplan, lead counsel in the case.

“We want to open our home to a child and make them feel safe, wanted, and loved,” said plaintiffs Brittany Rowell and Jessica Harbuck, who are planning to marry in January. “And we would be honored to be able to change the life of a child.”

LGBT rights advocates the Campaign for Southern Equality and Family Equality Council join the case as plaintiffs representing LGBT families across Mississippi. The case has been assigned to U.S. District Judge Dan Jordan.