My understanding is that because of the decision about the constitutionality of DOMA and the position that the administration is taking, that we will no longer defend DOMA going forward.
February 2011: The Obama administration instructs the U.S. Justice Department to stop defending the constitutionality of the Defense of Marriage Act in court.
Of course, books can be written to explain all the intricate details of the law, its administration, its history, and the various arguments for and against its constitutionality.