Excusing Humanitarian Intervention – A Reply to Jure Vidmar

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The US strikes in Syria, for which the US offered no legal justification, have once again ignited the debate on the qualification of such acts as illegal but legitimate – a label that had been used, in its day, to describe NATO’s use of force in Kosovo. Legally speaking, what does this sentence mean? Jure Vidmar, in his post on this blog, attempted to explain it by means of the distinction between justification and excuse. As Vidmar explains, excuses usually (but by no means always) cover situations in which conduct, while illegal, is nevertheless the morally right thing to do in the circumstances. He sees this type of reasoning behind the reactions of other States to the US action – expressing support for the action as the right thing to do, but unwilling to go as far as to say that the conduct was permitted or lawful.

The argument is certainly plausible (although note that no State has used the language of excuse in these circumstances which is, in my view, somewhat problematic for the argument). However, it raises a number of important issues which may, ultimately, undermine the very purpose of excusing an actor engaged in humanitarian intervention. I want to consider three of these here: (i) the current recognition of excuses in international law; (ii) the availability of excuses in respect of the breach of peremptory rules; and, (iii) the potential effects of excusing states for humanitarian intervention. I will address each of these in turn.

Excuses in International Law

Excuses are defences that arise from properties or characteristics of actors which, while having no effect on the illegality of the act, shield that actor from responsibility for its (illegal) actions. By contrast, justifications are defences that arise from properties or characteristics of acts and have the effect of rendering those acts lawful, despite apparently breaching a rule of the legal order.

Does international law recognise this type of defence? It is difficult to say. To begin with, ‘excuse’ is a legal concept (not a rule) so it is not, as such, susceptible of recognition by means of state practice and opinio juris. At any rate, states have rarely expressed their views in the abstract about this notion: only Burkina Faso, France, India, Japan, Mexico, Morocco, Russia, Slovakia, Switzerland and the UK, expressed support for excuses during the International Law Commission’s (ILC) work on responsibility. Moreover, there is sufficient variation in domestic legal orders to prevent the conclusion that excuses constitute a general principle of law: while they are generally recognised in Civil law jurisdictions, Common law jurisdictions only rarely do so.

Perhaps a better way to test this is to query whether specific defences have been classified as excuses by states and whether tribunals have applied them as such. Of the defences in the ILC’s Articles on Responsibility of States (ARS), it is the plea of necessity which tends to be seen as an excuse. This is, however, predominantly a doctrinal view. Indeed, only a few states have favoured a classification of necessity as an excuse. On the whole states have treated this defence as a justification. For example, this is how both Argentina and Zimbabwe pleaded it in investment arbitration. Tribunals too have applied the defence as a justification. The practice of states and tribunals in this regard is compatible with the current formulation of the plea in ARS Article 25. Article 25 formulates the defence as a lesser-evil it is afforded for the protection of ‘essential interests’ at the expense of non-essential interests, when the former are threatened by a grave and imminent peril. Lesser-evil is a consequentialist theory of justification pursuant to which whatever causes the lesser of two evils is lawful. Or, to put it in the opposite terms, whatever produces a net benefit is lawful: since the act in necessity produces a net benefit by preserving a superior interest, then it is lawful. The plea of necessity can be formulated as an excuse. Indeed, defences are not inherently justifications or excuses and indeed they can be formulated in either terms. An excuse of necessity could, for example, focus on the constraints on the state’s freedom of choice in the situation of necessity, namely the situation in which one of its essential interests is threatened by a grave and imminent peril. But this is not how it is now formulated, argued by states or applied by tribunals.

While it may be desirable to recognise excuses in international law (and I am of the opinion that it would be desirable to do so), I don’t think an argument can be made at present that excuses are already recognised in international law.

Excuses and Peremptory Rules

Assuming that an excuse exists in positive law which covers the situation of humanitarian intervention, can it be invoked as against the prohibition of force? Defences in the law of responsibility are subject to the limitation codified in ARS Article 26: they may not be invoked against peremptory rules. Since the prohibition of aggression is one such peremptory rule, a State will not be able to rely on a defence in respect of actions contrary to the prohibition. Admittedly ARS Article 26 uses the expression ‘circumstances precluding wrongfulness’ (the equivalent of ‘justification’). But I think that the limitation in ARS Article 26 must extend to excuses as well. Let me explain why.

If it were accepted that excuses can be invoked against the breach of peremptory rules, the consequence of this would be that a violation of one such rule would carry no responsibility for its author (so, it would not be bound by obligations of cessation and reparation). But recall that peremptory rules have consequences also for other states (Article 41 ARS). What happens with these consequences when the author of the breach is excused? These states do not benefit from the excuse (excuses, after all, are personal). So are these other States still bound by the obligations in Article 41? It would be odd to reach the conclusion that the State who has violated a peremptory rule does not bear any consequences, but that other States nevertheless do. If the US were excused for its airstrikes, then the US would not be responsible (in the sense of owing cessation and reparation) towards Syria but, nevertheless, other States would be bound by the obligation to bring to the US measures to an end and not to provide aid or assistance to the US. To avoid this paradoxical situation, it has to be accepted that excuses (like justifications) cannot be invoked in relation to peremptory rules.

What Effect would an Excuse have in these Circumstances?

Assuming that excuses are applicable in respect of peremptory rules (or, even, that the prohibition of force is not a peremptory rule), then what would be the effect of excusing a State engaging in humanitarian intervention? An excuse precludes the responsibility of a state for an act in violation of international law. So, in this case, the US would be relieved of its obligations of cessation and reparation (the ‘content’ of responsibility, in the terminology of the ARS). Crucially, however, there are certain consequences of wrongful acts that excuses cannot exclude.

Wrongful acts have other consequences beyond those in the law of responsibility. Examples of this are the invalidity of treaties as a result of a breach of the prohibition on the use of force and the possibility to terminate or suspend a treaty as a result of material breach. Now these consequences are not included in the notion of responsibility and, as a result, they may not be precluded by the excuse. Of particular interest here is the right of self-defence. This right arises in response to a violation of the prohibition of force by way of an armed attack. So self-defence is, too, a consequence of wrongfulness. Roberto Ago argued during the first reading of the ARS that self-defence was a consequence of wrongfulness encompassed by the notion of responsibility, but on second reading the ILC did not go along with that understanding. This being the case, an excuse could not preclude this right from arising. In other words, a State may be able to resort to self-defence against an excused actor when the latter’s wrongful act constitutes a violation of the prohibition of force amounting to an armed attack. Thus, to say that the US is excused for its airstrikes in Syria (should these amount to an armed attack) would leave it open to the use of self-defensive force by Syria. And this is, most certainly, an undesirable conclusion.

I accept that this argument depends on a conception of excuse which is concerned only with the exclusion of responsibility. But then, this is the only conception of excuse that states have so far considered (as this was the notion of excuse that the ILC considered in its work during the ARS).


Humanitarian intervention raises profoundly difficult questions for the international legal order, ranging from the scope and limits of unilateralism (who can act in humanitarian intervention and who is the judge that action is necessary?), to the scope and normative pull of the prohibition of force (does the acceptance of humanitarian intervention weaken or reassert the strength of the prohibition?), to the processes of law creation and change in the international legal order (are these one-off incidents or is there a pattern, and how many are necessary for a change in the law?). Testament to these difficulties are the many posts on these recent strikes both here and in other blogs (see, for example, here, here, and here).

Analysing humanitarian intervention through the prism of excuses may potentially address some of these uncertainties, most importantly the question of the impact of this conduct (if a pattern emerges) on the normative pull of the prohibition of force. But regrettably, it does so at the cost of adding additional uncertainties as this post shows.

I’d like to conclude with a historical note of caution. When in 1914 Germany invaded Belgium and Luxembourg, it pleaded necessity as an excuse. German Chancellor von Bethmann-Holleweg said: ‘Necessity knows no law. Our troops have occupied Luxembourg, and perhaps have already entered Belgian territory. Gentlemen, that is a breach of international law … We have been obliged to refuse to pay attention to the justifiable protests of Belgium and Luxembourg. The wrong – I speak openly – the wrong we are thereby committing we will try to make good as soon as our military aims have been attained. He who is menaced, as we are, and is fighting for his all can only consider how he is to hack his way through.’ (The translation is from L Zuckerman, The Rape of Belgium: The Untold Story of World War I (NYU Press, 2004), 11.)

Seeing where that led, I am not sure that – given that it is certainly not law at present – it is desirable for international law to develop to excuse uses of force beyond those expressly permitted (and therefore lawful) by the Charter.

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Kriangsak Kittichaisaree says

April 27, 2017

‘Excuses’ and ‘justifications’ as defences under domestic criminal law cannot be automatically transposed into public international law. (By the way, international criminal law, e.g., the Rome Statute of the ICC, uses the terminology ‘grounds for excluding criminal responsibility’.)
In domestic criminal law as well as in international criminal law, the issue is that of individual criminal responsibility, as determined by the forum State and the international community (through the UNSC acting under Chapter VII of the UN Charter in the case of the ICTY, ICTR etc., and treaties binding upon the States Parties thereto), respectively. All individuals are equal before these bodies of law.
However, in public international law, we are talking about State responsibility. If a State is entitled to an ‘excuse’/’justification’ irrespective of any contrary prohibition under the UN Charter and jus cogens, can we avoid living in a lawless world order? Not all States are equal in terms of international political clout and military might. Should a State get away with international sanction if its unilateral act is undertaken with ‘excuses’/’justifications’? Who is to be the judge of whether such ‘excuses’/’justifications’ are permissible? The UNSC (but deadlocked!!), the ICJ (but jurisdiction hurdles!)?

This is not to say that the US military action against Syria early this month was in violation of public international law. Without a reasoned legal opinion by the US Govt. in support of the action, we have been guessing what the international legal bases behind the action were.

Federica Paddeu says

April 29, 2017

Dear Kriangsak,

Thanks for your comment – there really are a lot of interesting and crucial points packed in such a short observation! I’ll give you my thoughts on what I think are the three main themes of your remark.

First, on the question of transposition of justification and excuse from criminal law to international law. You are absolutely right that these notions cannot be transposed. And my argument (or that of others who have discussed this topic) is not that they are indeed transposed. Justification and excuse certainly are concepts employed by the criminal law, but they are also concepts recognised in moral philosophy and in ordinary language. Indeed, JL Austin’s point in ‘A Plea for Excuses’ (1956-1957) 57 Proc Arist Soc 1, is that there is a difference in ordinary language between accepting responsibility, but denying that what one has done is bad (justification) and admitting that what one has done is bad, but not accepting full or any responsibility (excuse). This difference can be accommodated by the law – certainly by domestic law. But it seems to me that it can also be accommodated by international law. The recognition of justification and excuse in international law does not need transposition from criminal law; it is much more a question of developing these concepts within and for international law. That is, of developing conceptions of justification and excuse which are workable in the international legal order. In this sense, to develop these notions is no different from developing notions about complicity (on which there was recently a wonderful discussion focussing on Miles Jackson’s book on the topic) or about, say, compensation for damage.
Second, you query whether any of this is useful given that there are no mandatory and centralised means of dispute settlement or enforcement in international law. But then, one could ask this question about the whole of international law. States act, in the first instance, on the basis of unilateral and subjective appreciations of situations. They may later find out that their appreciation was wrong and be found responsible (as usually happens to states claiming justifications); but ‘autointerpretation’, to put it in Leo Gross’s terms, is the norm. At any rate, it seems to me that, even if there is no centralised judiciary or enforcement, it is not pointless to distinguish between these two notions. For one, knowing whether a certain argument is offered as a justification or an excuse may be important in the reactions of other states and, potentially, in diplomatic negotiations. For example, your hand in negotiation is likely to be stronger when you know the other party has done something wrongful – they are excused, but their act is wrongful nonetheless. Or, states may wish to react differently to the relevant conduct if it is justified (and, as such, permissible) or whether the actor is excused. And these reactions, as has been highlighted by others in this blog, can have an impact on the normative pull of the rule in question.
Finally, you raise the point of the invocation of defences and jus cogens. This is certainly a complex one. In principle, states cannot invoke either justifications or excuses in respect of conduct in contravention with a rule of jus cogens (See Art 26 ARS). But, as Jure Vidmar was commenting in reply to the comments on his post, it is not of the essence of peremptory rules to be absolute – they may be qualified. So long as they are qualified, the prohibitions they enshrine do leave some, let’s say, ‘holes’ of permissible action. This issue seems to be especially relevant for the prohibition of force and its exceptions. For instance, the ILC explained the right of self-defence as a qualification on the scope of the prohibition of force; in short, on this view, self- under international law force is prohibited only if it is not used in self-defence (See Commentary to Art 21, [1]). I used to think this was a satisfactory explanation; but I am now not so sure. So all I can say about this specific point is that positive law accepts the prohibition of force, it accepts that some or part of the prohibition is peremptory, but it also accepts that it has some exceptions. And this is undisputable. Nevertheless, we are still missing a theory capable of systematically and coherently explaining these three phenomena. A good – if brief! – illustration of different theories in this regard was given by André de Hoogh in ‘Jus Cogens and the Use of Armed Force’ in Weller, M. (ed), Oxford Handbook of the Use of Force in International Law (OUP, 2015), 1161, so I refer you to that for further exploration.
Best wishes,


ps: my apologies for the late response, I'm on maternity leave and my time is a bit constrained...