International Law – and the Unwilling and Unable Test – for US Military Operations in Syria

I greatly appreciate Professor Mike Lewis’s contribution to our discussion of international law on potential US airstrikes inside Syria. In this post, I reply to Mike’s concerns about the framework I described in a post I wrote last month, and I elaborate a bit on my earlier analysis.

At the Council on Foreign Relations yesterday, Senator Carl Levin succinctly explained the US legal position: “Under international law, the President … has authority to act in Syria, because the Syrian government has proven unwilling or unable to address the ISIS threat from its ungoverned territories” (my emphasis added).

Indeed, the two-prong “unwilling or unable” test will likely become central to the US position, as Mike would agree.

In the earlier post, I argued that a complication arises because Syria has stated that it would voluntarily cooperate with the United States in carrying out strikes against ISIS and that “any strike which is not coordinated with the [Syrian] government will be considered as aggression.”

Mike argues this is no complication: “Whether they [Syria] are willing to cooperate with the US strikes against ISIS is irrelevant to this analysis.” And Mike raises policy concerns about including consideration of Syria’s willingness to cooperate in the analysis of whether it is legal for the US to use force in Syrian territory.

Mike and I may actually share important areas of agreement as well as disagreement. I have four reactions to Mike’s post:

1. Mike’s conception of the law of self-defense includes a serious error. In conclusion, he writes that if the United States uses force because Assad is unwilling or unable to stop ISIL, Syria nevertheless, “can rightfully interpret any strikes as aggression” and Syria would be “justified in taking steps to prevent such attacks and to destroy the drones/aircraft conducting such attacks.”

That gives away the game.

If Syria can rightfully deem the US actions aggression and act accordingly, then we are not operating in a world in which the US has a real claim to act lawfully in conducting airstrikes in self-defense inside Syrian territory.

Over at Opinio Juris, Kevin Jon Heller has already penned a criticism of Mike’s conception of the law of self-defense, which describes the flaw in Mike’s analysis better than I could.

In the end, I am not even sure why our debate about the unwilling or unable test is worth the candle—if the conclusion of Mike’s position is that Syria could nevertheless “rightfully interpret” the US strikes as “aggression” and be “justified” in using force to attack the United States.

2. Mike overlooks the similarity of our positions or, more strongly put, how much my position accounts for the principal concerns that he raises.

Mike raises the concern that “the host/target state will use its veto power to prevent the intervening state from effectively dealing with the threat.” But, as I wrote, the United States could argue that “the involvement of Syrian military and intelligence would compromise the effectiveness of the operations to the point that the operations would not be able to deal effectively with the ISIS threat.” In other words, such a situation could satisfy the “unable” prong of the test.

Mike raises the concern that permitting the host state to exercise direction over the operations in some cases is “likely to result in the direction being misused by that state.” But, as I wrote, “the United States could argue that Assad is not acting in good faith.” In other words, such actions on Assad’s part could satisfy the “unwilling” prong.

3. Mike’s claims about the content of the “unwilling and unable” test assume the existence of well-defined, if not highly specified, customary international rules (and sub-rules) on this subject. But even leading proponents of an unwilling or unable test admit its contours are not well defined and the basic rule itself may not even enjoy customary international law status (Daniel Bethlehem; Ashley Deeks). For instance, it’s worth re-reading Ashley Deeks’ law review article on this topic, especially the section entitled, “The Test’s Substantive Indeterminacy.” She writes: “one is left with certainty that the test exists, but puzzlement about how states do or should apply it;” “[t]his raises questions about how effectively the test, in its current state, can guide states’ decisions about when to use force;” “scholars, like states, generally recite the test without discussing its meaning;” “[i]n its current, incompletely theorized condition, the ‘unwilling or unable’ test is not serving this purpose as well as it could;” and “[w]e thus have a rule without clear legal content.”

Mike’s claims about the precise scope, content, and status of the unwilling or unable test glosses over these profound deficiencies in the “law.”

4. Finally, is the host state’s willingness to cooperate truly irrelevant to the analysis of self-defense? Mike and my disagreement might boil down to semantics (i.e., what name we assign to this part of the analysis).  Proponents of the unwilling or unable test recognize that it permits the threatened state to use force only when there is “no other reasonably available effective means” to address the threat, and the threatened state “must provide an opportunity for the reluctant host to agree to a reasonable and effective plan of action.”

So what if the host state offers a form of military cooperation that is a genuine, reasonably available effective means to quell the threat? On this view, it appears the host state’s consent cannot be overridden.  If the threatened state (the United States) has other reasons it does not want to deal with the host state (Syria), which have nothing to do with the effectiveness  of this military option, we would  need to look for such justification outside the bounds of the self-defense (and the unwilling or unable) framework.

If the reason for rejecting Syria’s offer of military cooperation is based on Assad’s acting in bad faith or the inefficiencies of that option, that’s a completely different story. 

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Ryan Goodman

Co-Editor-in-Chief of Just Security, Anne and Joel Ehrenkranz Professor of Law at New York University School of Law, former Special Counsel to the General Counsel of the Department of Defense (2015-2016). You can follow him on Twitter @rgoodlaw.