As media are reporting, high-level discussions in Washington, D.C. and elsewhere are focusing on how governments should respond to the incident in Syria involving an alleged chemical weapons attack by the Syrian regime. These discussions include consideration of military strikes against Syria. Earlier, in light of conclusions that the Assad government had used chemical weapons on a small scale, deliberations about arming Syrian rebels raised questions of international law and other sources of law (EU law, US law). See, for example, Pierre-Emmanuel Dupont’s Arms Control Law post on this issue.
At present, the debate about direct military strikes is dominated by non-legal questions, such as (1) clarifying what happened and who is responsible (on which see Jean Pascal Zanders’ posts on Arms Control Law and The Trench), (2) further danger to US credibility given existing controversies about President Obama’s “red line” statements, and (3) whether military intervention would be prudent or effective. However, as suggested by gathering momentum for military action, legal issues are on the agenda internationally and within governments contemplating the use of force. So, here are some preliminary, general thoughts on these legal questions.
In terms of international law, two critical, linked issues are (1) the principles on state responsibility (did a chemical weapons attack occur, and was the Syrian government responsible?), and (2) the rules on the use of force (does a chemical weapons attack attributable to the Syrian government provide a justification for other states to use force against Syria?).
The cleanest scenario would be for the evidence to show that the Syrian government used chemical weapons, and, then, for the Security Council to authorize UN member states to respond with military force to this threat to international peace and security.
For many reasons, this scenario is unlikely to be the one that plays out. At the moment, it appears as if definitive attribution of this attack to the Syrian government will prove time-consuming, difficult, and politically contentious, leaving enough room and time for differences among members of the Security Council to produce opposition to a resolution authorizing the use of force against Syria.
The next strongest basis for using force, the right to use force in self-defense, is not an option because the attack in question was not perpetrated against another state. Nor, at the moment, would an argument of anticipatory or pre-emptive self-defense be persuasive as a justification for using force.
That leaves the more controversial option of justifying a use of force under the “responsibility to protect” (R2P) principle, or (to the extent it is considered distinct from R2P) under the older idea of humanitarian intervention. This option is controversial because, among other things, whether a state can rely on these grounds to use force without Security Council authorization remains hotly debated, indicating that no consensus exists in international law on this question. The Syrian conflict, and the humanitarian debacle associated with it, has revealed the depth of disagreement about, and the difficulties associated with, the R2P principle in international law.
However, even given this controversy, the large-scale use of chemical weapons by a government against civilians in a civil war constitutes an atrocity of sufficient gravity that states can, with some force, argue that international law permits military action against that government without authorization of the Security Council. This argument will agitate the long-standing legal controversy in this area, but the controversy cuts both ways in that its existence means neither position is beyond the legal pale. Potentially effective ways to manage the controversy in order to tip opinion in the direction of using force without Security Council authorization include (1) producing clear and convincing evidence of Syrian government responsibility for a chemical weapons attack, (2) making good faith efforts to try to obtain Security Council authorization for a use of force, and (3) ensuring serious multilateral support for, and participation in, military action against Syria.
In terms of US law, military strikes by US armed forces would bring questions of constitutional war powers into play, as well as the War Powers Resolution (WPR). Most recently, controversies about the application of constitutional war powers and the WPR erupted in connection with the US air campaign against Libya. To much debate, the Obama administration argued that US military activities against Libya did not constitute “war” under the Constitution or “hostilities” under the WPR. Whether the administration would use the same reasoning with respect to military action against Syria depends on many factors, including the scope and seriousness of US military efforts.
However, we know enough to understand that Libya and Syria are not comparable. To date, US reluctance to get involved militarily in Syria flows, in part, from a realization Syria presents a harder target, and a more difficult operational context, than Libya. These differences would probably require more extensive, much riskier military activities than the US was able to undertake against Libya. Legally, it would be harder to sustain the position that such activities do not constitute “war” under the Constitution or “hostilities” under the WPR. Further, very limited military actions designed to permit re-use of the legal positions taken in the Libya incident could undermine the international legal case that military force is justified in responding to a large-scale atrocity committed with chemical weapons.
To avoid constitutional and statutory problems, the President could seek congressional authorization to use force, but the wisdom of US military intervention into the Syrian conflict has been, and currently is, at issue in Washington, D.C., even in light of the alleged chemical weapons atrocity. Given this, and the nasty political climate between the White House and Congress, it is difficult to believe that Congress would declare war on Syria absent some development that would dramatically change the political calculations inside the Beltway.