We’re all trying to sort through the reports and evidence about the use of chemical weapons, specifically sarin gas, in Syria, allegedly by Syrian government forces.  A lot is being said about whether the evidence of use is persuasive, and if so what sort of use it likely was/is – i.e. intentional use by government forces, an accident, etc.

I thought I’d chime in on the question of international law relevant to the use of chemical weapons by Syrian government forces, if that is indeed what has occurred. Chemical weapons possession and use is comprehensively regulated and essentially prohibited by the 1993 Chemical Weapons Convention (CWC), which is a masterwork of treaty drafting and construction. See Chapter 2 in my 2009 book for a thorough explication of the CWC.  

The CWC built upon the 1925 Geneva Gas Protocol, which proscribed the use of chemical and biological weapons in war.

Specifically on the use of CW, Additional Protocol I to the 1949 Geneva Conventions, of which Syria is a party, prohibits the use in armed conflict of weapons “of a nature to cause superfluous injury or unnecessary suffering.”

Syria is not a party to the CWC. However, it is beyond doubt that the essential prohibitions contained in the CWC regarding both possession and use of CW, have passed into customary international law, and are thus binding on all states, including Syria.  Syria is, though, a party to the 1925 Geneva Gas Protocol, so there is no question that Syria is bound by both conventional and customary international law to not use CW in war.  I have seen it written that the 1925 Geneva Protocol “implicitly, does not cover internal or civil conflicts.” I actually don’t think that’s accurate, given later developments in the law of armed conflict, in which the essential rules of the LOAC have been understood to have both passed into customary law, and to apply to both international armed conflicts and non-international armed conflicts.

In a case like Syria, where we are undoubtedly dealing with a non-international armed conflict, the essential rules of the LOAC apply, and this includes the 1925 Geneva Protocol as well as Additional Protocol I to the Geneva Conventions.  These conventions and the parallel customary international law attached to them, very clearly prohibit the use of chemical weapons during armed conflict.  So I think there is no doubt that, if indeed chemical weapons have been utilized by Syrian government forces, Syria has violated the law of armed conflict.

So where does that take us? Well, as we all know, President Obama has said that the use of CW in Syria would be a “game changer” and would cross a “red line” (a whole new vocabulary we seem to be working with here!).  This raises the question, why would the use of CW by the Syrian regime be such a game changer and cross such a red line, when we’ve been watching the regime slaughter its people with conventional weapons for years?  This is a good question. I think it’s best answered by Max Fisher in the New York Times:  

[T]he reason is about more than just Syria: it’s about every war that comes after, about what kind of warfare the world is willing to allow, about preserving the small but crucial gains we’ve made over the last century in constraining warfare in its most terrible forms.

One of the few positive outcomes of World War I was the Geneva Protocol of 1925, in which world leaders agreed that they would no longer use chemical or biological weapons. They wanted to change not just international law but international norms, both of which were further codified by the 1972 biological weapons convention and the 1993 chemical weapons convention. The idea was that war, sadly, is going to happen. But if we can all agree not to use chemical weapons, warfare will be less terrible.

It’s largely worked: With a few notable exceptions, the taboo against chemical weapons has held up. Even in some of the most vicious conflicts of the past few decades, otherwise ruthless armies and rebels have largely refrained from using chemical weapons. That’s a remarkable achievement and one of the world’s few successes in constraining warfare. Keeping Syrian leader Bashar al-Assad’s regime from breaking the chemical weapons taboo is about more than just what happens in Syria: It’s about maintaining the international norm against chemical warfare, about ensuring that present and future wars will not redeploy the awful chemical weapons that made the First World War so much worse than it would have otherwise been.

I agree with Fisher that this is a norm worth supporting. But from a legal perspective, just because CW are used in a non-international armed conflict like Syria, it doesn’t automatically give third states a legal justification for intervening in the conflict to stop their use. That may sound ridiculous to the non-lawyers out there. But international law still stakes Westphalian sovereignty very seriously, and does not permit interventions into sovereign states’ territory without a legal justification that can form an exception to the U.N. Charter’s broad prohibition on international uses of force in Article 2(4).

Over at Opinio Juris, there are a couple of thoughtful pieces by Julian Ku and Deborah Pearlstein on this subject of on what international legal justification an intervention into Syria by the US could be based. Julian particularly references an earlier post of his, and links to responses to that post by Daniel Bethlehem and Ashley Deeks. I encourage readers to view these posts, as they will give you the contours of the legal debate.

I personally am not very persuaded by either Bethlehem’s or Deeks’ legal justifications for a US intervention, even if CW have been unlawfully used by the Syrian regime.  I share Julian’s essential skepticism that such an international use of force would be lawful.

That being said, I’ve thought for some time now that more should be done by the US to support the Syrian opposition forces against the Assad government forces. From supplies of both food and military materiel, to the establishment of no-fly zones enforced by US aircraft, I would support any and all such measures that wouldn’t put US boots on the ground, but would significantly support the opposition in Syria. I know there are a lot of problems with identifying who the opposition is, and a lot of concern about what comes next after Assad falls. But it seems to me that the opposition, even with its fractures, appears to represent the Syrian people much better than the Assad government ever has. And if the regime is now using chemical weapons against the opposition and civilians, I don’t think that the US can sit by any longer and watch this humanitarian tragedy unfold.

As usual, I’m trying to separate what I think the correct analysis of the lex lata is, from what I think should actually be done in the situation. I don’t like fudging the law to support what I think should be done. Here, I think the law is against outside intervention by the US, even if CW have been used. But I don’t think that should be the only factor in considering whether humanity and morality dictate action.