While our ongoing war in Syria regularly gets lost amidst other also-pressing news, the growing set of clashes between U.S. military and forces allied with Syrian President Bashar al-Assad led Congress this summer to begin asking whether the President actually has legal authority to start a new kind of war in the Middle East. The U.S. military has of course been engaged in anti-ISIL operations in Syria since 2014. But violence in recent months – including an incident in June in which the U.S. military shot down a Syrian jet, as well as multiple U.S. efforts to defend its creation of a "de-confliction zone" in Syria, an area surrounding a garrison used by U.S. Special Forces to train partner forces there – involves the United States far more directly in state-to-state conflict with Syria (and its allies, Iran and Russia) than we have previously been. Apart from the serious policy implications of this kind of escalation, it is far from apparent what domestic legal authority supports it.
One possibility the Administration has advanced is that the anti-Syria actions are impliedly authorized by the 2001 Authorization for the Use of Military Force (AUMF), a statute that gave the President the power to use "all necessary and appropriate force" against those nations, organizations or persons he determines were responsible for the attacks of September 11. The Obama Administration indeed relied on the 2001 AUMF for its operations against ISIL in Syria. And while scholars and policymakers alike have written critically about the plausibility of relying on a 2001 AUMF to attack a group that did not come into existence until years after 2001 (and is indeed today the sworn enemy of Al Qaeda, the group that was responsible for the attacks of 2001), we might set those arguments aside at least initially to consider the new claim on its own – that is, to the extent the AUMF supports U.S. operations in Syria at all, it surely also must include implied authority to defend U.S. forces operating there against any attack.
The notion that the AUMF contains some implied authority for U.S. troops operating under its auspices to defend themselves against foreign attack is in one sense entirely plausible. If, as the Supreme Court held in 2004ǯs Hamdi v. Rumsfeld, the AUMF contains implied authority to detain war prisoners because such detention was a recognized incident of the use of force under international law, then surely self-defense of one’s own forces (at least to the extent permitted by international law) should also be within the realm of implied statutory authority. The problem is,
U.S. self-defense is not what most of these recent incidents have involved. By the United States’ own account, the Syrian SU-22 we shot down was firing on local anti-Assad fighters the United States supports, but U.S. forces were not at risk. CENTCOM rather explained that the move was in "collective self-defense" of coalition-partnered forces – a concept that appears pulled from Article 51 of the UN Charter (a treaty we are obligated to observe as supreme law of the land under our own Constitution’s Article VI) providing in relevant part: "Nothing in the present Charter shall impair the inherent right of individual or collective self-defense if an armed attack occurs against a Member of the United Nations." But Article 51 by its terms limits the right of "collective" self-defense to UN member states. Local anti-Assad forces, whatever their merits, aren’t states. More, especially to the extent our establishment of a "de-confliction zone" is effectively seizing an area inside Syrian territory for our use and defending it from incursion by Syrian forces, we are not engaging in defense (self or otherwise) at all, but rather in the partial armed occupation of another country – which is, to put it mildly, the opposite of a recognized incident of force under international law.
So, what about finding implied authority in the AUMF under principles of statutory interpretation unrelated to international law – based on text, context or legislative history? To pursue this theory, it is impossible to look just at the Administration’s latest interpretive move, but rather at the set of inferences one would have to draw from the AUMF itself. For buying the notion that the 2001 AUMF authorizes U.S. bombing of Syrian or Syrian-allied forces requires us to embrace not just one dicey inference, but three: (1) that a statute limited by its text to authorizing force against the groups that attacked us in 2001 extends to a group that did not exist in 2001 (and is itself at war with the group that did attack us in 2001); (2) that the statute includes some implied authority to defend our own forces from attack not only against those groups the statute authorizes us to fight, but as against any nations and organizations anywhere worldwide our AUMF operations extend; and (3) that the statute further authorizes us to "defend" any local group with which we might ally in the course of global AUMF operations – including by excluding a sovereign state from its own territory in order to secure training space for the local group.
It is implausible that the Congress that passed the 2001 AUMF thought it was authorizing all this. The textual limitation of the 2001 AUMF to the groups responsible for the attacks of 9/11; longstanding canons of statutory interpretation that would favor reading a statute to accord with our binding treaty obligations where possible; and the total absence in legislative history of any intention to authorize force against Syria and Iran – all weigh against any such construction. Which leaves us with the President’s power under Article II of the Constitution.
It is certainly true that the President has constitutional authority to act in defense of U.S. facilities and troops overseas without first waiting for Congress to act, a necessary extension of the President’s well settled power to "repel sudden attacks." From this principle, one scholar has suggested that the President may also attack Syrian aircraft (or Iranian drones or any non-ISIS force in Syria) – in the interest of defending U.S.-allied Syrian government rebels. As the argument goes, the President’s self-defensive authority should be understood to extend to the defense of certain organized third parties (whether a state like Britain or our allied non-state Syrian forces) operating "in close coordination with the U.S. military in a combat setting." In such a setting, our interests are closely enough aligned, and our forces closely enough entangled, that an attack or threatened attack on a third-party ally is effectively the same as an attack on us.
This "third party self-defense" theory of Article II is in one sense quite a bit narrower than the currently prevailing position of the Justice Department Office of Legal Counsel (OLC) – which, under President Obama, took the view in striking Libya without prior congressional authorization in 2011 that the President has authority to use military force on his own so long as an important U.S. interest was at stake, and so long as the degree of contemplated force didn’t actually amount to "war" within the meaning of the Constitution’s "declare war" clause. Under this OLC view – based in part on OLC's assessment of post-World War II presidential practice – one need not develop any specialized theory of third party self-defense to justify the use of executive power here. The current President could assert one of several U.S. concerns in Syria as the important interest at stake (say, protecting the interest of regional stability), and so long as the strikes were limited in scope and duration (i.e., less than "war"), all of these counter-Syria actions could be said to fall within the scope of Article II, whether in defense of allies or not.
Yet there are at least three ways in which this "third party defense" notion may be said to go beyond even the earlier broad OLC conception of presidential power. First, there is no previous practice in which the President has asserted the interest of defending battlefield allies as such as a justification for authorizing the use of force abroad. It is surely one of the difficulties with the Obama OLC opinion that it leaves so open-ended the question of what counts as a "national interest" sufficiently important for the President to use force, but if we are to take seriously the notion that past practice matters here, it would seem important to identify some at least analogous illustration on which to rely. Second, again to the extent such practice matters, the case for using force to protect a zone in a foreign country within which our own military might train opposition forces seems vastly less persuasive than the interest in, for instance, ridding the world of the scourge of chemical weapons. Indeed, the "de-confliction" zone we are now using force to protect is just over the border from Iraq, where we have every right to operate militarily (thanks to Iraqi consent) and, presumably, train anti-ISIL forces all we like.
Above all, in the 2011 Libya strike (and almost all previous post-World War II operations), the unilateral executive use of force abroad was taken in concert with UN authorities. Both our downing of the Syrian jet and other recent U.S. strikes appear to be in violation of the UN Charter. Whether one considers that an Article II problem, an Article VI problem, or simply a violation of international law– the United States’ legal position here is as precarious as it gets.