The United States, Britain, and France have attacked various chemical weapons facilities in Syria. Even before they acted, a number of commentators claimed that any such attack would be internationally unlawful. Below, I explain why that claim is too simplistic and how we should situate the operation in the jus ad bellum going forward. Let me say at the outset that I don’t support this operation and have serious doubts about the capacity of the United States, in particular, to implement a coherent policy in Syria. (I also think the operation violates U.S. law.) So, I’m not arguing that the operation was a good idea or even that it should be lawful. I’m making an analytic argument about how the jus ad bellum works.
The April 2017 Incident
This was not the first attack against Syria for its use of chemical weapons. In April 2017, the United States struck Syria for the same asserted reason: as a reprisal for the regime’s use of chemical weapons in violation of international law. At the time, most commentators said that the U.S. operation was unlawful. It was inconsistent with the longstanding interpretation of Article 2(4) of the UN Charter and not covered by the Charter exceptions. Assad didn’t consent to the operation, the Security Council hadn’t authorized it, and it wasn’t taken in self-defense.
There is an ongoing debate about whether the jus ad bellum contains another exception for humanitarian interventions. The dominant view is that it does not. States (as a group) have periodically condoned unilateral operations that can be labeled “humanitarian,” but the vast majority of them have declined to support a generally applicable humanitarian exception to 2(4). They have instead insisted that no such exception exists. Further, even if there were one, its application to the 2017 operation would have been dubious. The operation looked more like a reprisal than like what we usually mean by a “humanitarian intervention.” President Trump said that it was designed “to prevent and deter the spread and use of deadly chemical weapons,” not to avert the many other atrocities that were being committed in Syria. Forcible reprisals are by almost all accounts unlawful.
So, it would be hard to show that the 2017 operation was consistent with the formal legal doctrine on the use of force. For a sophisticated analysis of why, see the latest piece by Jack Goldsmith and Oona Hathaway at Lawfare. I think Jack and Oona are basically right as far as the doctrine goes. But I also think the doctrine doesn’t get us very far. We know that, in the jus ad bellum, as in other areas of international law, the formal legal doctrine is at times dissociated from the law’s operation. If we want to describe or understand how the law actually plays out in concrete cases, we have to go beyond it.
And when we do, we see something that might be surprising. States broadly condoned the 2017 operation against Syria. Eleven states expressly endorsed it at the UN Security Council the next day: Australia, France, Germany, Italy, the Netherlands, New Zealand, Saudi Arabia, Turkey, the United Kingdom, and Ukraine. Several other states — Canada, Israel, Poland, Qatar, the UAE, Bahrain, Kuwait, Jordan, and Spain—supported the U.S. operation in alternative arenas. So did the European Union. A different group of states, including China, expressed ambivalence about the U.S. operation; these states neither supported nor criticized what the United States had done. Only a small handful of states, including Iran, Syria, and Russia, expressly condemned the operation as unlawful.
The 2017 incident thus was not a case in which one state discretely uses force and others look the other way. The United States publicly owned what it did. The Security Council met to discuss it. Many other states affirmatively supported it. And very few states were willing even to say that it was unlawful. Here, states (as a group) made a decision on the law; they decided to deprive Article 2(4) of both its operational relevance and its normative bite. That looks a lot like deciding to make the operation lawful.
I say “looks like,” because I’m not arguing that the 2017 operation was actually lawful. As discussed, I don’t think it satisfied the formal legal doctrine. But I also don’t think that ends the legal inquiry. The jus ad bellum consists of more than just the doctrinal standards. It consists of a broader set of social institutions, practices, and expectations. So, in my view, the lawfulness of the 2017 operation is an open question and less clear-cut than the formalist doctrine would suggest. What’s significant is that almost every state acted as if, or almost as if, the 2017 operation was lawful.
A Legal Precedent?
Of course, any incident can be a precedent in the sense that it happened. The critical question is to what extent states may rely on it to justify a subsequent operation, like the one that the United States, the United Kingdom, and France undertook on Friday night.
Two responses to that question are common and, in my view, not compelling. One goes something like this: the 2017 incident is not legally relevant because it occurred entirely outside of and in contempt of the law. To take this claim seriously, one would have to accept that the vast majority of states openly disregarded the law in 2017, that many of them publicly defended their insubordination at the very institution that is legally charged with assessing this conduct, and that nothing happened in response. Those who have advanced this claim have not offered an account of why states bothered to go to the Council and endorse the U.S. operation, if they were acting outside the law, or why the best interpretation of what they were doing at the Council — when they were explaining their decisions not to apply Article 2(4) — is practicing not law but a kind of politics that is antithetical to law. I do not find that argument persuasive. But even if it were, its implications would be profound: it would suggest that the jus ad bellum is irrelevant not just to the United States but also to the Security Council and the many states that endorsed or supported, in one way or another, the U.S. action in 2017. It would also suggest that, in 2018, states that wanted to use force in Syria could do so without giving the law much thought.
A second response is to read the 2017 incident as evidence that the legal doctrine is not as I have described it — to say that the jus ad bellum actually contains or is developing a formal exception to Article 2(4) for cases like the 2017 operation. A few scholars took this position at the time. They suggested that there is or might be a general standard that licenses force in an entire category of cases (however that category is defined). The problem with this position is that it distorts what states did in 2017. They clearly signaled that their support for the U.S. operation was contingent on the facts and not a reliable indicator of how they would respond in the future. The reaction was meant to be fact-specific—to condone one operation, without purporting to apply or establish a standard of general applicability.
That tactic is not new and sometimes works. Unlike a general standard, which automatically applies to and helps justify every operation that falls within its scope, a fact-specific decision is designed only for the case at hand. The reaction in 2017 was not meant to be controlling in or a sufficient justification for any subsequent operation. The problem is that the facts in Syria in 2018 almost replicate those from 2017. In both cases, limited, targeted air strikes were launched after the Security Council failed to take meaningful action in response to reports that the Assad regime used chemical weapons against its own people. So, the precedent is directly on point. It is very good evidence of states’ expectations and normative priorities for this situation.
And, indeed, it largely foreshadowed the reaction to the latest attack. Despite the views of many international lawyers on Twitter and elsewhere, it is striking how many states have once again condoned or supported the operation against Syria for its use of chemical weapons. According to news reports, only three states — Russia, China, and Bolivia — backed a draft Security Council resolution that would have condemned the operation as an act of aggression. Eight states voted against the resolution, and four states abstained on it.
Appraising the 2018 Operation (and the Jus ad Bellum)
Though the pattern from 2017 seems to have carried over, it is still too early to know what to make of the 2018 operation or what it reveals for the jus ad bellum going forward. But for now, I want to leave you with five takeaway points.
First, the fact that the jus ad bellum did not constrain the states that used force against Syria does not mean that it was irrelevant. Although the modern jus ad bellum is often described as an instrument of peace and a constraint on cross-border force, it has always also facilitated some force. When it licenses force, it legitimizes that conduct in law. In these circumstances, it makes force easier to execute and more difficult to challenge than it otherwise would be. This means that the jus ad bellum can be relevant and effective even when it does not inhibit states from taking or supporting legally dubious operations. It might still confer legitimacy on or deny legitimacy to a given operation. For the operations in Syria, the jus ad bellum put the states that wanted to use force in the position of having to work to legitimize their conduct. Of course, these states might not have cared about their legitimacy, but they seemed to. Both in 2017 and in 2018, they expended considerable energy building a case for themselves at the Security Council.
Second, the fact that states have not defended the operation in expressly legal terms does not mean that their justifications are outside of law. As far as I know, the United Kingdom is the only state that has justified the 2018 operation in explicitly legal terms. It is one of the few states that recognizes a humanitarian exception to Article 2(4) and has invoked that exception here. By contrast, in 2017, the United States presented a set of case-specific considerations that, in its view, warranted the use of force. It did not expressly assert that it was acting lawfully. Neither did the states that supported it. I suspect that the United States and most other states will follow a similar script in 2018.
Some international lawyers have interpreted that to mean that the United States and its supporters did not present a legal justification for the 2017 operation. This position assumes that a justification is “legal” only if it expressly invokes a variant of the word “law” or relies on the formal doctrine. I think that position misunderstand how states engage with the jus ad vellum — that thus how the jus ad bellum actually operates — in cases like these. In 2017 and today, the United States and other states that have supported it have made claims on the law. They have argued, if only implicitly, against the application of Article 2(4). They have argued that the legal prohibition of chemical weapons is nearly sacrosanct and can, in certain circumstances, justify a forcible response. These are arguments about the law.
Third, if the reactions in 2018 look like the ones in 2017, it would not be evidence that states recognize or want to create an exception to Article 2(4) for an entire category of humanitarian interventions or reprisals. They plainly do not. States are balancing a number of competing considerations and have decided that not applying Article 2(4) was preferable to the alternatives in these cases.
Fourth, given the conflicting messages that states themselves are communicating, the best answer to the question of whether the two operations are lawful is not a simple “yes” or “no.” Such answers contain an element of advocacy; claims of legality or illegality are normative statements dressed up as descriptive ones. In my view, the answer to that question has to be more nuanced, contingent, and qualified.
Finally, these sorts of decisions rightly raise slippery slope concerns. If the United States and its friends may use force unilaterally when they please, what’s to stop other states from doing the same? I begin to tackle that question in my forthcoming article. For now, it’s worth keeping in mind that the jus ad bellum has never worked as it was originally intended. The challenge has always been to find ways to maintain its relevance and normative salience in a deeply imperfect world. As I intimated here and elaborate on in my article, the best way to preserve its regulatory purchase in today’s security environment is almost certainly not to squeeze, into the four corners of the formal legal doctrine, every operation that states choose to conduct, tolerate, and support. The gap between the formal doctrine and this practice might be unsatisfying, but it is not necessarily dysfunctional — or worse than the available alternatives.