Jack Goldsmith and Matthew Wexman make a persuasive case that Obama has set important precedents for the expansion of presidential war powers:

And it is Obama, not Bush, who has proven the master of unilateral war. Because of his lofty rhetoric about principle, because he sometimes appears to be a reluctant commander-in-chief, and perhaps because his claims of legal authority have been advanced and defended by lawyers who did not bring to office a reputation for hardline executive supremacy, the war powers precedents Obama has established have not been appreciated. Yet for those same reasons they will be especially credible, and thus especially tempting, to future administrations. These precedents will constitute a remarkable legacy of expanded presidential power to use military force.

The authors review the administration’s justifications for the Libyan war, the abortive strikes on Syria last year, and the new war against ISIS, and they show that Obama and his officials have embraced the idea that the president can wage war on his own authority. Obama sought Congressional authorization last year for the proposed attack on Syria, but only after he made clear that he didn’t believe that he needed their approval to start a war on his own. Sometimes this has involved pretending that a sustained air campaign does not rise to the level of “hostilities,” as administration lawyers did during the Libyan war in 2011, and sometimes it has involved lying about what the 2001 and 2002 AUMFs permit, but in practice Obama has gone farther than any recent president in waging wars without Congressional authorization. Obama is “reluctant” to use force until he isn’t, at which point he has proven himself to be less concerned with legality than any of his modern predecessors. What makes this even more obnoxious is that Obama and his officials claim to be more respectful of constitutional limits on presidential power than previous administrations, and they have gone so far as to accept the constitutionality of the War Powers Resolution, but they then completely ignore all of these limits when it comes time to make policy.