DETROIT — April DeBoer and Jayne Rowse, a lesbian couple from suburban Detroit, are challenging a state ban that Michigan voters placed in their constitution nine years ago, regarding  same-sex marriage, in federal court this month.  The law also prevents single people from jointly adopting children in Michigan.

DeBoer has adopted a girl and Rowse two boys, and the couple has lived together for more than six years. Seen by the State as single people living together, however, they are not allowed to adopt each other’s children jointly.

They first challenged Michigan’s adoption law in 2012 in federal court in Detroit and later expanded the lawsuit to contest the marriage ban. U.S. District Judge Bernard Friedman last July ruled that they were entitled to their day in court.

Thirteen states and the District of Columbia allow same-sex nuptials. Thirty-five states ban same-sex marriage by statute, through constitutional amendments defining marriage as a union between one man and one woman, or both.

Gay couples in several states have brought legal challenges since the U.S. Supreme Court in June threw out a key part of the Defense of Marriage Act, which barred same-sex couples from federal marriage benefits.