This weekend’s chemical attacks against civilians in Syria—and the Trump administration’s likely military response—highlight an intensifying dilemma underlying international law on the use of force. The confused state of the law, and the state practice increasingly occurring outside of it, threatens to undermine the UN system’s already limited ability to constrain state violence. Given this crisis, improvements to the current legal framework are desperately needed. An improved legal framework using a qualitative threshold—legitimizing humanitarian intervention against regimes that use chemical and biological weapons (CBW) on civilians—can offer a way forward for both protecting civilians and strengthening international law in the UN system.

Few Bases for Action under International Law

Despite the severity of the Syrian regime’s past chemical attacks against civilians, and their almost universal condemnation, the legal justification for previous U.S. strikes against the Syrian regime has been hotly debated. Without falling under the UN Charter’s exceptions for intervention — Security Council authorization under Chapter VIII or Article 51’s provision for self-defense — there seems to be little direct authorization for the strikes under the UN framework. No explicit authorization exists for the use of force outside of these exceptions.

Politically motivated vetoes, as have been cast before by Russia, will likely continue to prevent Security Council authorization for more forceful measures. Similarly, a doctrine of “unilateral” (or unauthorized) humanitarian intervention, which would open the door to legality for interventions not explicitly authorized under the UN Charter, finds limited support among states and legal scholars.

However, despite this proscription in the current UN framework, state practice in Kosovo, Syria, and elsewhere—and the muted reaction of much of the international community—suggest that a notable number of states in the international system may in reality be tacitly accepting a diverging norm. Such divergence was captured by U.S. Ambassador to the UN Nikki Haley in April 2017, when she said, in response to the Khan Sheikhoun chemical attack, that “when the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action.” Soon after her remarks at the UN, President Donald Trump ordered the U.S. military to strike the air base in Syria from where the chemical attack was launched.

This disconnect between formal legal principle and state practice, as well as the dissonance between the Charter’s guiding principles of both sovereignty and humanity, creates more than just confusion in the international system. Rather, this gap poses a threat to the very legitimacy and capacity of international law to guide state behavior—risking casting international law into irrelevance as states act to promote both state interests and humanitarian principles.

Opposition to Humanitarian Intervention Under Current Law

Perhaps the most fundamental objection to a doctrine of humanitarian intervention under current international law is the subjective nature of determining the legitimacy of any such intervention—in essence, identifying true “humanitarian” crises necessitating the use of force. As noted by many commentators, the difficulty in identifying a just cause remains a significant stumbling block for the development of such a doctrine. One state’s “humanitarian” intervention is often another state’s aggression falsely justified under a humanitarian pretext.

This problem derives from the fact that current bases for humanitarian intervention, as conceived by proponents, rely upon ambiguously defined and implicitly quantitative measures of harm. The current “soft” Responsibility to Protect (R2P) framework, adopted under the 2005 World Summit Outcome Document, embodies this ambiguity: In it, UN General Assembly members pledged to take action in cases of “genocide, war crimes, ethnic cleansing and crimes against humanity.” Determination of such crimes, of course, is itself a subjective exercise. What level of civilian atrocity rises to the legal threshold for such crimes: 100,000 deaths? 1,000? 100? What types of atrocities should trigger culpability? And most fundamentally, who should make the determination when triggering crimes occur?

A Qualitative Threshold for Humanitarian Intervention: Responses to CBW Attacks

The Syria crisis, and its associated instances of chemical and biological weapons (CBW) use against civilians, marks a key moment for scholars, statesmen, and practitioners to envision an improved legal framework on humanitarian intervention. The Trump administration’s repeated use of force in Syria, as well as its ongoing acceptance by the vast majority of states, points the way to the development of a qualitative-based legal threshold for unilateral humanitarian inventions: interventions in response to CBW use against civilians.

Instead of relying on ambiguous quantitative thresholds to determine legitimate interventions, the Syria strikes represent an opportunity to consider developing in the UN-system qualitative thresholds for authorizing unilateral humanitarian intervention in cases of Security Council paralysis. Such qualitative thresholds would capitalize on cases where there is little debate regarding the severity of humanitarian need or the interests of states in addressing it—cases such as CBW use against civilians.

As I explored in an earlier analysis, under such a framework, unilateral intervention in response to CBW attacks on civilians could be authorized and deemed legitimate under international law, even without approval by the full Security Council. To provide a further check against such a doctrine becoming a cover for illegitimate state aggression, this framework for R2P intervention against CBW use could require a further condition of approval by a super-majority of permanent Security Council members. Such a framework would ensure that a single vetoing state could not paralyze UN members’ actions against CBW-employing regimes.

Despite many scholars’ and states’ deeply ingrained opposition to a general doctrine of humanitarian intervention, such interventions have gained broader global support in particular cases. Witness the tacit acceptance by many non-Western governments of  NATO’s “illegal but legitimate” intervention in Kosovo, or the widespread global support for the April 2017 U.S. strikes in Syria. These cases tell us that it is likely not humanitarian intervention per se that is generally problematic, but the potential for abuse of such doctrine under the current quantitative and subjective measures of assessment.

An official determination of CBW use against civilians, obviously an essential triggering finding under such a legal construct, would be a key procedural element that would need to be established in accordance with UN practice. Such a determination would likely need to be made by an independent, UN-established commission, the Organization for the Prohibition of Chemical Weapons, or some other body of qualified independent experts.

Such a condition, authorizing but not requiring the use of force, would have the normative benefit of giving the international community greater flexibility to stop CBW use against civilians and save innocent lives in cases of CBW atrocities, while also narrowly limiting contexts under which a single Security Council veto could be disregarded. Under this model, there would be little debate about the legality of the intent of force in response to a humanitarian crisis. Instead, the only issue for dispute would be the factual question of the act of CBW use itself. Such a framework could limit endless debates in the Security Council about whether the nature or harm to civilians rose to the threshold of “genocide” or “ethnic cleansing,” because numbers of deaths or the level of atrocities would not be relevant to the ultimate decision.

Such a framework could generate much greater support among positions traditionally skeptical of a humanitarian intervention doctrine. Many states would likely be more open to such a framework than a traditional doctrine of humanitarian intervention because it’s inherently limited in its scope. That’s because only a few states today possess CBW capability, therefore any such legal framework would pose little threat to states’ security or sovereignty. Additionally, the objective nature of the CBW standard would limit the abuse of the humanitarian criteria: States would find it difficult to justify aggressive interventions as “humanitarian,” as in the case of Russia’s invasion of Georgia. Additionally, this framework could gain greater support from legal formalists based on its bright line, its objective requirements for intervention, and its maintenance of the Security Council’s final role in the authorization of force.

Clearly the political challenges facing such a proposal are formidable. In its 72-year history, the UN has adopted few formal changes to its governing principles on the use of force. Even more daunting, the permanent members of the Security Council have little incentive to dilute their authority over authorizing state force. However, those promoting the Charter’s principle of humanity will find many reasons to support the broadening of international legal provisions to protect civilians. Similarly, those promoting the legitimacy and power of international law will find many reasons to support improving the law’s authority over state practice.

R2P supporters should thus work toward promoting legal principles authorizing unilateral intervention in cases of government CBW usage against civilians, gearing efforts toward beginning formal international consideration on adopting such a provision within the R2P framework—with an ultimate goal of securing adoption within the UN General Assembly and Security Council.

While the possibility of adoption of such a framework may be distant, the conversation associated with this debate could have lasting effects in shaping a currently broken UN system. Such a development could, in the long run, help to promote human rights, deter future CBW attacks, and ultimately strengthen the law’s ability to promote humanity and justice in the international system.

Image: Drew Angerer/Getty