No Defense for DOMA

Ruth Marcus and the Washington Post Editorial Board evidently insist that all laws, no matter how repugnant (e.g., DOMA), deserve their day in court and a vigorous defense. (I believe this principle applies to people, but not to laws.) How far would they take this? Is there no conceivable law so repugnant that they would actually condemn its legal defense team? Not even one allowing slavery or forced abortions?