Excusing Illegal Use of Force: From Illegal but Legitimate to Legal Because it is Legitimate?

The US missile strikes on Syria have, inter alia, revived the debates on humanitarian intervention, the argument of ‘illegal but legitimate’ and more generally on the exceptions to the prohibition of the use of force. For some examples see here, here and here. Some contributors have pointed out that the US did not even try to bring this action within the ambit of the Charter rules on the use of force, and that the absence of Charter-based arguments may even be a good thing as it preserves the strength of Article 2(4). Others have cautioned that the strength of the rules on the use of force might nevertheless be undermined, as singular ‘exceptional’ cases result in a pattern.

This post argues that, analogous to the concept of defences in municipal legal systems, international law on the use of force should adopt a systematic distinction between justifications and excuses. As responses to the US missile attack in Syria demonstrate, the two concepts are conflated. The result is that legality is often assessed on the basis of excuses. If the trend of conflation continues, the controversial doctrine of ‘illegal but legitimate’ will move toward an even more controversial doctrine of ‘legal because it is legitimate’.

Justifications are legally-warranted exceptions to the general prohibition. As such, they are a way out of illegality. Excuses, on the other hand, are not a way out of illegality, but act as mitigating circumstances that preclude responsibility for an otherwise illegal conduct. Under some circumstances, breaching the law may indeed be the choice of a lesser evil. As noted by Vaughan Lowe in his 1999 EJIL article, a legal system may wish to provide a defence for emergency drivers who breach the speed limit on the way to hospital. There are two ways of achieving this goal. One way is to give them an explicit authorization to breach the speed limit. The other one, however, does not authorize speeding, but rather ensures that emergency drivers are not prosecuted upon such a breach of traffic rules. The first (justification) relaxes the norm itself and may well result in wider disobeying of the speed limit than the second, which merely provides for a carefully weighed excuse of culpability where the norm was doubtlessly breached. In other words, it is better if the general norm is strong and ‘catches’ more violators whose excuses are then considered on a case-by-case basis. I elaborate on these issues in more details in this 2015 concept paper. In the present context, might the ‘emergency driver logic’ apply to the US strike in Syria? Even if it did, it would not make this action legal. Possibly, the US could only escape responsibility for this internationally wrongful act. 

The Charter justifications and extra-Charter excuses

The Charter regulation on the use of force adopts a clear logic of justifications. Article 2(4) spells out the prima facie prohibition, while Articles 39+42 and Article 51 give legal authorization for a departure from this general rule. When properly used pursuant to Articles 39+42 or Article 51, force in international law is not illegal. Because it is justified.

The humanitarian intervention and R2P doctrines can, in principle, fit into the Charter justifications, but not as independent legal concepts. They can operate via Articles 39+42. The humanitarian intervention and R2P doctrines can underlie political decisions for Security Council’s authorization of force. But what if compelling moral reasons for an intervention exist and the Security Council does not act? This is the ‘illegal but legitimate’ type of reasoning, which was advanced most prominently in the situation of Kosovo. It has not always been popular in international legal scholarship, but it reflects the very logic of excuses.

The legitimacy criteria for humanitarian intervention and other instances of extra-Charter use of force, which have been developed by several scholars and governments, can thus only be considered as criteria for assessing the plausibility of an excuse for an otherwise illegal use of force. But they do not serve as justifications. In the present context, even the statement of the US Permanent Representative to the UN, Nikki Haley, builds on the logic of excuse rather than justification, as does the statement of President Donald Trump.

Was the US missile attack excusable? In the decentralized international legal system, it is ultimately – for the most part – other states who judge this. Some of them have indeed been quite willing to accept the excuse [see here for a summary of some reactions]. However, the supporting states did not expressly say the attack was legal. They commonly expressed their understanding and support, which is quite different. From this point of view, I agree with Monica Hakimi that the strength of Article 2(4) is preserved. It could be a separate problem, however, if states accepted each other’s excuses too easily, as may well have been the case here. The end result could then indeed be what Anthea Roberts has cautioned against.

The main challenge is whether the separation of justifications and excuses can work in a decentralized legal system. But this is a problem of international law in general, not only in this specific context. In my view, the conceptual difference is still worth preserving in the international legal system. Keeping the Charter-mandated justifications and extra-Charter excuses separate would at least keep us paddling in the already-dangerous but probably-inevitable waters of ‘illegal but legitimate’. Any extra-Charter uses of force would thus remain doubtlessly illegal. As such, they could not be taken as evidence of state practice to claim a new customary exception to the prohibition of the use of force. Conflating justifications and excuses would mean that states might in the future completely drop the Charter language and invoke excuses to get out of illegality. This would then create a legal and policy framework for wider disobedience of the rules on the use of force and undermine the Charter rules. If Kosovo laid the foundation stone for ‘illegal but legitimate’, we need to be careful that Syria does not become the foundation stone for ‘legal because it is legitimate’.