Bruce Ackerman and Oona Hathaway argue at the Huffington Post that President Obama lacks the constitutional authority to impose a no-fly zone in Libya in the absence of congressional authorization. Their main argument is that “[i]f Obama goes it alone, he must return to Bush-era assertions that the president, as commander-in-chief, can unilaterally launch the nation into war.” This is wrong, for several reasons. George W. Bush sought and received congressional approval for both of his wars – against those responsible for 9/11, and in Iraq. Bush did proclaim unilateral presidential power to engage in preemptive self-defense, broadly conceived. But that rationale is not in play here, for as Ackerman and Hathaway note, “nobody suggests that Gaddafi’s assault on his domestic enemies is a threat to the United States.” Ackerman and Hathaway further claim that “President Obama immediately withdrew opinions written by John Yoo and others making . . . extreme claims” about the president’s power unilaterally to launch the nation into war. But this did not happen. Obama officials withdrew many Bush-era OLC opinions. But they did not withdraw the two very broad opinions in support of the president’s unilateral war powers related to terrorism and Iraq (and indeed probably never had an opportunity to consider them before now).