The Department of Justice has just filed a new brief in the Smelt case that defends the constitutionality of DoMA, but also states the Obama administration's opposition to DoMA as a policy matter and explicitly repudiates anti-gay arguments based on parenting. It was DoJ's earlier brief in this case that prompted a firestorm of criticism from lgbt advocates.
The new brief continues to argue that sexual orientation classifications are subject to only rational basis review and that Congress was justified in enacting DoMA. So the bottom line defense hasn't changed. (There was never much reason to imagine that DoJ would fail to defend DoMA in court, however, especially in this across-the-board challenge.)
The most powerful and important aspect of this new brief is its categorical statement that there is no rational basis for the arguments in favor of discrimination that are grounded in claims about procreation and child-rearing. (See quotes below) This puts the federal government on record as to these claims in a way that has never happened before.
From the brief (emphasis is mine):
…[T]he government does not contend that there are legitimate government interests in "creating a legal structure that promotes the raising of children by both of their biological parents" or that the government's interest in "responsible procreation" justifies [DoMA]. [Multiple professional groups] have issued policies opposing restrictions on lesbian and gay parenting because they concluded, based on numerous studies, that children raised by gay and lesbian parents are as likely to be well-adjusted as children raised by heterosexual parents…[T]he United States does not believe that DoMA is rationally related to any legitimate government interests in procreation and child-rearing and is therefore not relying upon any such interest to defend DoMA's constitutionality.
In addition, the new brief emphasizes much more than the first one did that plaintiffs' challenge to DoMA can be dismissed solely on jurisdictional and standing grounds, without reaching the merits at all.