Why won't the Justice Department let DOMA die?

The U.S. Department of Justice is arguing that the federal Defense of Marriage Act is constitutional, in spite of a district court's ruling to the contrary. DOJ lawyers filed a brief with the U.S. Court of Appeals for the First Circuit on Thursday, saying the law is "supported by an interest in maintaining the status quo and uniformity on the federal level, and preserving room for the development of policy in the states." 

Come on, Justice Department, it's time to legalize gay already!