The defense of DOMA has been taken up by the US House, who passed the bill, since Homobama and his Gaystapo "justice" dept have refused to do their constitutional duty. It's actually better this way, because the DOJ's previous efforts to "defend" DOMA were a laughable charade, if not downright sabotage.
This is only one of several attacks on DOMA that the House's appointed counsel are fighting - on both coasts.