I'm not a fan of the Defense of Marriage Act, but I do have a large problem with the politicization of the role of the Department of Justice. Strip away the gay-rights issue and consider the question: what would Democrats say if, in 2013, President Sarah Palin announced that her Department of Justice would refuse to defend the constitutionality of Obamacare in court? There is no provision in the Constitution for a retroactive veto. Compare and contrast the Bush administration Department of Justice, which steadfastly (and successfully) defended McCain-Feingold and enforced FACEA. Earlier.
Update: Orin Kerr has the same thought.