It will ask the state attorney general to allow the group to amend a complaint in an existing case regarding second-parent adoptions, The (Raleigh) News & Observer reported.
The case, filed in Greensboro in 2012, involves six same-sex couples and challenges a state ban on second-parent adoptions, which occur when one partner in an unmarried couple, gay or straight, adopts the other partner's child.
Chis Brook, legal director of the ACLU of North Carolina, said if Attorney General Roy Cooper agrees to the request, he would not be agreeing to same-sex marriage, merely allowing the ACLU to make its case against North Carolina's same-sex marriage ban in court.
"All we're asking is they consent to our amending the complaint," Brook said.
Brook added a recent U.S. Supreme Court ruling, striking down portions of the federal Defense of Marriage Act, helped link second-parent adoptions and same-sex marriages.
"The Supreme Court focused on the harm to families and to children that comes when marriages are not recognized by the government," Brook said.