A lesbian couple's desire to adopt each other's children has grown into a potentially groundbreaking challenge to Michigan's ban on same-sex marriage.

April DeBoer adopted a girl, and her partner Jayne Rowse adopted two boys.

But Michigan law prevents them from adopting each other's children. DeBoer and Rowse say their civil rights are being violated.

Two Detroit-area nurses filed a lawsuit to try to overturn the state's prohibition on adoption by same-sex partners.

But federal Judge Bernard Friedman invited them to expand their case and take aim at the gay marriage ban.

Arguments are set for Thursday in a Detroit law school. MORE: Council of Michigan Indian tribe OKs gay marriage

~Deboer and Rowse with their children.~

If Friedman strikes down the gay marriage ban, supporters say gay couples could marry and acquire other rights, including adoption.

State officials, however, predict "potential legal chaos" if the judge throws out the ban.