Dr Shane Darcy is a lecturer at the Irish Centre for Human Rights, National University of Ireland Galway.
The anticipated use of military force against Syria in reaction to the use of chemical weapons does not meet the permitted exceptions to the prohibition on the use of force under the United Nations Charter. Security Council authorisation has not been forthcoming, while self-defence is obviously not applicable. Although British MPs have blocked a United Kingdom military intervention, the United Kingdom government had relied up on humanitarian intervention as the legal basis to justify the use of force. The doctrine is controversial and as Dapo Akande has shown, it at best has weak legal standing in international law. But the type of limited military intervention envisaged bears all the hallmarks of a reprisal, rather than humanitarian intervention, and this concept is equally problematic in modern international law.
Reprisals are a traditional means of law-enforcement, involving the unilateral use of force in response to breaches of international law. The Institut de Droit International defined reprisals involving the use of armed force in a resolution passed in 1934:
Reprisals are measures of coercion, derogating from the ordinary rules of international law, decided and taken by a State, in response to wrongful acts committed against it, by another State, and intended to impose on it, by pressure exerted through injury, the return to legality.
The purpose of military intervention against Syria seems to be both punitive and deterrent; to punish Syria using chemical weapons in breach of international law and to deter any further use. Such military action would be prima facie unlawful, in that it fails to meet the terms of the United Nations Charter. But might it be lawful as an armed reprisal?
International law has generally addressed two classes of reprisals as measures of self-help: armed reprisals involving the use of force short of war, and belligerent reprisals occurring during an armed conflict, taken in response to breaches of humanitarian law. Both have been traditionally governed by several customary international law requirements, including proportionality, last resort, temporariness, and authorisation at the highest level. Belligerent reprisals are not at issue here, because the United States is not a party to the conflict in Syria – in any event, such reprisals against military objectives are not prohibited, unlike those directed against civilians which are outlawed under the Geneva Conventions and Additional Protocol I.
Armed reprisals are widely considered as contrary to international law, although the United Nations Charter does not make any specific reference to such a prohibition. During the drafting of the Charter, the United States delegate at San Francisco clarified the drafters’ intention “to state in the broadest terms an absolute all-inclusive prohibition; the phrase “or in any other manner” was designed to insure that there should be no loopholes”. A rapporteur confirmed that “the unilateral use of force or similar coercive measures is not authorised or admitted”. Practice since the adoption of the Charter has confirmed the unlawfulness of armed reprisals. In 1964, the Security Council adopted Resolution 188 concerning British military action in Yemen, in which it “condemns reprisals as incompatible with the purposes and principles of the United Nations”. The General Assembly’s 1970 Declaration on Principles of International Law Concerning Friendly Relations and Cooperation among States sets out that “[S]tates have a duty to refrain from acts of reprisal involving the use of force”.
As I have detailed in a forthcoming book chapter, the widely-held view is that reprisals involving the use of force are thus unlawful, irrespective of whether the customary requirements such as proportionality or last resort are met. Nonetheless, scholars have often tried to revive the doctrine of reprisals as a justification for the use of force, most notably in the context of Israeli actions against its neighbours. The International Court of Justice has not made a unambiguous statement on the lawfulness of armed reprisals, having stated in Nuclear Weapons that they are “considered to be unlawful”. The majority of the Court was criticised in several of the separate opinions in the Oil Platforms case for failing to clarify the unlawfulness of reprisals involving the use of force. The International Law Commission considers that the reprisals prohibition has “acquired the status of a customary rule of international law”.
The justification of reprisal has not been raised in any official statements concerning the legality of using force against Syria, despite the obvious parallels, and this perhaps reflects States’ recognition of their unlawfulness. Some commentators have drawn on the reprisals doctrine, to either justify or oppose the use of force outside the parameters of the United Nations Charter. David Bosco at Foreign Policy notes that reprisals have “deep roots” in international law, and explains that “Western governments would be violating international law in order to defend it “. He fails to note the present illegality of reprisals, but sees the doctrine as a suitable basis for making Syria “pay a price” for its law-breaking. Professor Heather Roff writes that that conditions for reprisals would not be met if the United States attacked Syria, but more fundamentally, that the doctrine cannot apply because the United States is not a party to the conflict. This commentary has tended to confuse, somewhat understandably, the concepts of armed and belligerent reprisals.
There is no denying that many violations of international humanitarian law have been committed in Syria, including the use of chemical weapons, but some doubt has been raised regarding responsibility for the latter. An armed intervention by the United States in response to these violations would not have a lawful basis under present international law, either as self-defence, humanitarian intervention or an armed reprisal. This latter legal doctrine is a throwback to the days of unilateral enforcement, and has been rightly abandoned. Reprisals were mostly relied upon by those more powerful States and had a tendency to lead to escalation and further violations, rather than a return to respect for international law. There is no reason to suggest that this would be any different with Syria.