‘The prohibition of the use of force in Article 2(4) of the UN Charter is a strict one, and calls to widen the scope of self-defence should be resisted.’ Discuss.

Article 2(4) encompasses the customary international law of prohibition on use of force, with self-defence as a contentious exception to the principle. This essay will argue that: (1) Article 2(4) is a strict prohibition, (2) discuss arguments in favour of the statement and (3) discuss arguments challenging the statement. Overall, it can be concluded that widening the scope of self-defence could lead to abuses of power and uncertain laws, and therefore calls to expand the scope of the exception should be resisted. 

Article 2(4), as confirmed in the Nicaragua case, is a rule of customary international law, applying to all states. It is a “cornerstone of the United Nations Charter” (Armed Activities) that prohibits the “threat or use of force against the territorial integrity or political independence of any state”. There are two exceptions to this strict prohibition. Firstly, the Security Council’s power under Chapter VII to authorise force and secondly, the right to invoke self-defence under Article 51.  Some may argue it is not a strict provision as there are often ambiguous Security Council resolutions which allows states to construct the wording to justify their actions to their own pursuits. As Schachter (1984) notes, Article 2(4) “is not a model of clarity”. These constructive ambiguities, however, are often not deliberately drafted and may be attributable to the difficulties in diplomatic negotiations, which riddle any political organ such as the Security Council. Another criticism is that states who have departed from the principle have only been met with condemnation, rather than sanctions. Yet, just because the UN cannot sanction a state, does not mean they validate the condemned acts. Overall, however, there is a swathe of state practice and ICJ opinions that convincingly demonstrate that the prohibition is a strict one, with force being the absolute exception to the general circumstances. 

On the one hand, widening the scope of self-defence to an open-ended exception runs the risk of “effectively destroy[ing] the overarching rule prohibiting the use of force” (Bruneé and Toope, 2018). Article 2(4) operates to maintain peace, and as Schachter (1984) observes, “an invasion, however brief in duration, violates the essence of territorial integrity” – opportunities to use force should thus be confined as much as possible. Trapp (2008) further insists that necessity and proportionality must “operate to limit the right to use force in self-defence”.

Furthermore, widening the scope of self-defence would create uncertainties, which may lead to ideological clashes which will “sooner or later become clashes of power” (Schachter). Inevitably, different states with different cultures, histories, economic and political structures will have differing views on what international law should be. As Roberts (2019) notes, international law is not as universal as it appears to be. To widen the scope of self-defence muddies the waters further. Bruneé and Toope believe the goal of self-defence is “to provide an objective threshold for action” and highlight the risks “inherent in unreviewable and unclear standards”. 

The concept of ‘imminent’ attacks has been used to stretch the concept of self-defence, with proponents advocating anticipatory and preventative self-defence. The US and UK attempted to rely on the concept of ‘imminence’ in relation to invading Iraq in 2003 and ISIS in Syria respectively.  The ICJ has explicitly left the question open as to whether an armed attack need to have occurred for self-defence can be invoked with Judge Simma in Armed Activities noting that the Courts pronouncements in Nicaragua “are problematic less for the things they say then for the questions they leave open”. Bowett (1958) believes it is unreasonable to expect a state to “await an initial attack” which “may well destroy that state’s capacity for further resistance and so jeopardise its very existence”. Conversely, Henkin (1963) believes the drafting is “clear [and] unambiguous” and he strongly contests the idea of anticipatory and pre-emptive self-defence, stating “it is precisely in the age of the major deterrent that nations should not be encouraged to strike first”. Considering the anticipatory right to self-defence is hotly contested, it is no wonder that. President Bush attempt to invoke the broader ‘preventative’ self-defence doctrine under his National Security Strategy in 2002 was met with very little support. Gray believes such “a unilateral right of pre-emptive self-defence would be dangerously destabilizing”, with Sanger believing that this stretches the concept of imminence to “breaking point”. 

Another call to widen the defence has been through the ‘unwilling and unable doctrine’. Whilst some view this “as a component within the pre-existing necessity principle” (Noam Lubell), Bruneé and Toope believe that the evidence does not support the existence of such a standard in current customary law. The purported doctrine is only supported without caveat by five states: USA, Australia, Israel, Turkey and the UK. Even so, the arguments proposed have been accused of being “lukewarm [and] often incoherent” (ibid) with popular support for the rule greatly exaggerated. Bruneé and Toope recognise that if this standard was to materialise in international law, will it be applied generally to all states, rather than being targeted at the global south? For example, is it possible to imagine France invoking self-defence actions within Belgium after the Paris attacks of November 2016? This is unlikely and highlights the dangers of norm entrepreneurship from states which dominate discourse in academic literature and policy briefs. Overall, state practice has consistently resisted any attempts to expand the justifications for self-defence, including the 120 states of the Non-Aligned movement. As Schachter (1984) noted: “the world will not be made safe for democracy through new wars or invasions of weak by the strong” and the widening of the scope of self-defence should thus be resisted. 

On the other hand, there are compelling arguments in support of widening the doctrine of self-defence, such as keeping up with modern times.  From a historic perspective, Art 2(4) was designed in post-war era, where drafters presumably envisioned ‘armed attacks’ as traditional warring-style armies. As Harris (2018) notes, the law on self-defence has historically been most concerned with large-scale attacks of the “classical sort” (as in Falkland Islands) and lower scale “cross-border raids by guerrilla forces” (as in Nicaragua). Yet, post-9/11, we have arguably entered a new era of warfare, with non-state actors executing some of the worst acts of war in the modern century. Is there a practice gap between the black letter of the Charter and the bloody reality of world politics?  There has been growing agreement that States can lawfully invoke a right to self-defence against non-state actors. In the Wall Advisory Opinion, Judge Buergenthal declared that the inherent right of self-defence is not “dependent upon an armed attack by another State”. Yet, whilst there is an emerging general consensus, the parameters of such expansion are closely guarded, with a desire to avoid returning to the pre-1945 position where use of armed force was permitted in international law as a reprisal for an illegal act. Therefore, the scope of the defence should not be widened excessively. 

Legality is a separate concept from legitimacy, and there may be cases where use of force is unlawful, but perhaps legitimate. As Reisman (1984) notes, it is “naïve and indeed subversive…to insist that [coercion] never be used” as it is an “ubiquitous feature of all social life” and an “indispensable component of law”. Some may argue force should be allowed for a ‘good cause’. Yet, the idea that wars waged for a legitimate, ‘good’ cause such that territorial integrity and political independence would not be violated as per Article 2(4), is an “Orwellian construction” (Schachter) of the terms and is not supported in state practice. Moreover – who gets to determine what is legitimate use of force or not? The ICJ in Corfu Channel also rejected the UK’s argument of using armed force for ‘international justice’, reminding us of the historic realities of abuse by powerful states for supposedly good causes and of the dangers of expanding the defence too far. 

A niche and controversial argument is supported by Reisman, who asserts that Art 2(4) must be interpreted in terms of the fundamental postulate of political legitimacy in the 20th century – “the enhancement of the ongoing right of peoples to determine their own political destinies”. He believes Article 2(4) is “a means” to the overarching aim of self-determination and considers it a “rape of common sense” to deny the right of forcible intervention where self-determination is at risk. He thus would support an expansion of the right of self-defence.  Schachter offers a compelling counter argument to this thesis. He challenges the view that self-determination is the “main purpose” of international law and observes other important aims such as maintenance of peace and the prevention of aggression, which I believe are central to the spirit of Article 2(4). Likewise, McDougal and Feliciano (1961) also rejected the idea of using force to expand democratic values, believing this “involves a destruction of values incompatible with the overriding conception of human dignity”. On the whole, therefore, widening the scope of self-defence to such a precariously subjective position should be resisted. 

Recently, whenever global society has been asked to affirm expansions of the right to self-defence, the majority of States have resisted. Overall, whilst widening the scope of self-defence sounds attractive in theory for some, in practice it would create far more problems than solve, and is likely to disproportionately favour some states over others. It is thus more desirable that the scope of the defence is limited so as not to contradict the purpose of the prohibition under Article 2(4) as a whole, and maintain certainty and positive international relations wherever possible.  


The writer, Roshni Ranasinghe-de Silva, is a double First Class graduate from the University of Cambridge and future trainee solicitor at Slaughter and May. She ranked 6th in her cohort of 205 students at University, coming top in her cohort for both Family Law and EU Law.

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