Modern Justice Department opinions insist that the executive branch must enforce and defend laws. In the first article to systematically examine Department of Justice refusals to defend, we make four points. First, the duties to enforce and defend lack any sound basis in the Constitution. Hence, while President Obama is right to refuse to defend the DOMA, he is wrong to continue to enforce a law he believes is unconstitutional. Second, rather than being grounded in the Constitution, the duties are better explained by the Department of Justice’s (DOJ) desire to enhance its independence and status. By currying favor with the courts and Congress, the Department helps preserve its near-monopoly on government litigation authority. Third, our analysis of refusals to defend shows that the duty to defend only lightly constrains the executive, posing no real barrier to decisions not to defend the constitutionality of laws. Finally, the duty to defend serves no constitutional purpose. Its supposed benefits arise from getting the courts to opine on the constitutionality of laws. But courts typically have that opportunity as a result of executive enforcement of a law it believes is unconstitutional. Nothing further is gained by having the executive voice insincere and halfhearted arguments when others sincerely can advance strong ones. Or, we should say, nothing except enhancing the DOJ in the eyes of Congress and the courts at the expense of the President’s constitutional vision, which is what the duty to defend is all about.