Introduced by Micaela Frulli, Marco Roscini, Chiara Vitucci


The principle of non-intervention in the domestic affairs of other states is one of the cardinal principles of international law and there is hardly any doubt on its customary status, as the International Court of Justice has affirmed in several occasions. What is controversial, however, is its application in situations of internal unrest occurring in other countries, in particular in civil wars: May a state intervene to support a government and/or armed opposition groups involved in a civil war occurring abroad? Broadly speaking, there are two schools of thought. The traditional school argues that the principle of non-intervention is not affected by the occurrence of a civil war: a government, as the legitimate representative of a state, maintains its right to request external assistance to quell an insurrection, while the insurgents may never be supported, either directly or indirectly. According to the ‘negative equality’ school, on the other hand, the occurrence of a civil war deprives the government of its right to invoke external assistance to maintain internal order. This is because any external intervention in a civil war, on whichever side, would breach the right of internal self-determination of the people in question, which encompasses the right to choose its own political system without foreign interferences.

The present situation in Syria is particularly problematic. Russia and Iran have intervened on the side of the Assad government, while several European, American and Arab states have provided support to the Syrian opposition, mostly through the provision of arms, equipment, funding and training. In addition, a coalition of states have conducted airstrikes against the Islamic State in Syria without the Syrian government’s consent, while Turkey has provided logistical support to the airstrikes but at the same time has tried to prevent an advance of the Kurds in the region.

In light of the above, has the Syrian war (and other recent conflicts) affected the rules on foreign intervention in civil wars? Do the principle of internal self-determination and the fight against international terrorism play any role in establishing the legality of the foreign intervention? What is meant by ‘civil war’ in this context? And who is the ‘government’ of a state, ie the authority entitled to request foreign assistance (when this is admissible)?

QIL asked Olivier Corten and Pietro Pustorino, two legal scholars who have considered these questions in their research, to advance some answers to the issues at stake. The two authors chose different perspectives.

Olivier Corten argues that a principle of ‘neutrality’, resulting from the principle of self-determination, prohibits third states to intervene in a civil war on any side. In his view, Russia’s intervention in the Syrian civil war in support of the Assad government is not inconsistent with this conclusion, as Russia did not simply rely on Assad’s invitation as a legal basis for the intervention, but also pointed out on several occasions that she was acting only against terrorist groups and did not intend to frustrate the self-determination aspirations of the population against a dispotic ruler. Pietro Pustorino, on the other hand, mantains that the principle of neutrality has no basis in customary international law, as it is at odds with the recent and less recent practice of states and international organisations. In his view, third states are required not to intervene in support of opposition armed groups involved in a civil war, but remain free to assist the government requesting the intervention. The only case when insurgents may be supported is when they fight a regime that is responsible for grave, clear and independently ascertained violations of international law, as in the case of Libya and Syria.