The gruesome events in Paris could strengthen President Obama’s domestic war powers authority under Article II in two ways.
First, if the apparent ISIS threat that Washington is one of the next targets proves credible, then the President’s authority to act under Article II in self-defense of the nation is clarified and enhanced. The Paris attacks indicate clearly that the Islamic State has the intent and substantial capacity to wage large-scale violence in Western capitals. (The downing of the Russian airplane in international flight, if attributable to the Islamic State, only underscores the point.) The attacks, and the verbal warning, also enhance the imminence of the threat from the Islamic State, for those who think such imminence was lacking and is necessary.
Second, if NATO invokes Article V of the North Atlantic Treaty, it would trigger an international law obligation on the United States to “assist” France by taking “such action as [the United States] deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.” This international legal obligation is not in itself an authorization under domestic law for the use of force. I also doubt that the Executive branch would claim – as President Truman claimed under the UN Charter during the Korean War – that President Obama has a domestic duty (and thus power) under the Take Care clause to use force under the North Atlantic Treaty. Rather, under OLC precedents, the President would probably claim that his authority is enhanced because the United States has a powerful national interest in upholding the viability and credibility of its most important military alliance, and a powerful related interest in peace and security in Europe. The attacks on the Islamic State in Iraq and Syria have until now lacked the imprimatur of the United Nations or NATO that has been crucial to the legitimacy of presidential uses of force under Article II in prior OLC opinions; if NATO invokes Article V of the Treaty, that will change.
From the President’s legal perspective, his enhanced Article II powers don't matter much (if at all) because he believes Congress authorized him to use force against the Islamic State in the 2001 AUMF. For the President, the 2001 AUMF provides all the domestic legal authority he needs should he choose to ramp up force against the Islamic State – including more ground troops, and a geographically expanded projection of force – after Paris. (Note that this morning U.S. forces killed the Islamic State leader in Libya, an operation that “was underway before the Paris attacks began.”)
Nonetheless, if the President decides to expand the fight against Islamic State yet further, he would be wise to use this important moment to demand that Congress give him refreshed authorities to do so. This is less so for legal reasons than for political reasons. The events of the last 24 hours have made plain that the President was wrong yesterday to say that the Islamic State is “contained.” If after Paris the United States becomes part of a larger military push against the Islamic State, a push that might involve much more U.S. treasure and possible blood, the President needs to educate the nation about the stakes and risks, and get it fully on board. A speech from the Oval Office will not suffice. Rather, as I wrote last year, “only an extended and informed and serous national debate can do [adequately educate the country], and such a debate can only occur if the President asks for Congress’s support.” Getting Congress on board will brings the President additional benefits.
Congressional authorization to use force will give the President’s military and related actions against [the Islamic State] enormous political legitimacy, and will significantly spread the political risk when things go badly, as they invariably will. Congressional authorization will not stop some members of Congress from carping from the sidelines. But it will force every member of Congress to take a stand, and it will diminish the rate and significance of carping down the road. Congressional authorization will also protect the President politically to some degree should [the Islamic State] succeed in a strike on the U.S. homeland (as many are now warning is possible). For it will demonstrate in a high-profile manner that the President understood the stakes beforehand and did everything he could to prepare the nation for the threat and address it. Recall that the most serious charge against the Bush administration after 9/11 was that it failed to take seriously enough al Qaeda’s threat signals. President Obama has already been accused of this with respect to [the Islamic State], and anything he can do now to show how seriously he is taking the threat will help him later when things go badly. And again, there is simply no better way to signal the seriousness of the threat than through solicitation of congressional support.
The White House has never really made a strong push for an Islamic State AUMF (even though it did finally send up a draft this year). A strong push has not been a high priority because the President thinks he has the legal authorities he needs, because Congress has been divided, and because he has not wanted to put his name on a new statute that officially and indefinitely extends the war (though he did just that through interpretation of the AUMF).
There is also the hard and politically fraught question of what the AUMF would say. The President’s draft AUMF contained a faux ground troops “limitation” – “faux” because it limited only the President’s statutory authority under the new AUMF, and not his residual Article II and 2001 AUMF authorities to introduce ground troops. The President’s draft also had a very expansive “associated forces” definition. These and other elements were controversial in different quarters in Congress, and indeed any new AUMF may continue to divide the Congress along several political dimensions.
That in a nutshell is why I think the best approach now is to simply try to replicate the current substantive authorities that the President believes he possesses. (Or, as I once wrote in connection with this proposal, “a substantively neutral but procedurally constraining AUMF makes sense.”) The point of a new AUMF is not to enhance the President’s legal authorities – as noted, he currently thinks he has all the authorities he needs, including the authority to introduce ground troops if he thinks they are necessary. The point of a new AUMF is political legitimation. And while I think Congress now will and should be much more willing to get on board for a refreshed AUMF, it is highly unlikely that Congress will want to, or should, limit the President’s authorities at this moment – at least not substantively (though I think it would be useful, as I have long argued, to limit them procedurally through a sunset clause.)