Aesthetic Philosophy and the Art of Law in the International Community

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Inspired by Sir Hersch Lauterpacht’s writings, Mary Ellen  O’Connell, in the Art of Law in the International Community, provides a contemporary response to the ever increasing erosion by states –in the majority of  cases based on self-interest – of the most fundamental peremptory norm of the international legal order, the prohibition of the use of force. Such a response requires a renewal of the theory of international legal process (p. 6) consisting of a new approach to natural law (p. 7) drawing “on the arts and aesthetic philosophy “ and resulting in a fascinating “distinctive approach“ (p. 1). 

The prohibition on the use of force and the peaceful settlement of disputes are the two interconnected fundamental pillars of the international legal order.  Peace can only be maintained by a strict interpretation and compliance with the prohibition – allowing no room for derogation – and a revitalized process of peaceful resolution of disputes. 

The political theory of realism ignores natural law and manipulates customary international law (p. 10) to weaken the prohibition, whereas the two inherent, positive law exceptions to the prohibition – Security Council authorisation and the right of self-defence – in order to pass the good faith test  have to be interpreted narrowly (p. 11) . Natural law adduces general principles of necessity, proportionality, attribution, consent and equality as additional restrictions (p. 11). The jus cogens status of the prohibition and its associated principles cannot convincingly be explained by positivism. In a rather demanding but rewarding first chapter the author explains the rise of positivism to the detriment of natural law and then demonstrates how history and economics are incapable of satisfactorily substituting natural law, neither of them justifying altruism, something aesthetic philosophy can deliver (p. 33).

Aesthetic philosophy leads us to a refreshing and “persuasive theoretical explanation in support of extra-positive norms“(p. 33) such as peremptory ones, requiring “law compliance regardless of self-interest “(p. 42).  Beauty not only provides the “rationale for law in general and the explanation for its core principles” but it “also inspires action “(p. 48).

UN Charter Article 2(4) as Jus Cogens

Before dealing with the prohibition’s institutional component and the limited exception of self-defence the author in Chapter 2 thoroughly analyses the status and very substance of the prohibition in both positive and extra-positive law, manifesting the “hybrid” (p. 56) character of natural law.

The ‘inherent’ principles  mentioned earlier “operate much as jus cogens norms do“:  “(l)ike jus cogens“ (first emphasis added) they “may not be negated through treaty, contrary state practice, or interpretation“ (p. 65) and just like jus cogens  they require  the natural law theory as explanation (p. 65). Although they appear to be impregnated with its jus cogens character, it is important to note  that these principles – inherent as they are to the prohibition itself and “essential components of the lawful resort to force “ (p. 78)–   are not jus  cogens (p. 69) because they ”lack the substantive moral content of peremptory norms” (p. 72) . 

The author’s position is clear and persuasive:  the prohibition permits no derogation and its inherent exceptions can only be applied “in narrowly defined emergencies“(pp. 100 and 101). Hence, all attempts to weaken the rule or to expand its exceptions through either interpretation of the positive law provisions or the invocation of contrary state practice (pp. 72-76, 79-80) are doomed to fail. Butchard’s argument – starting from the so-called inherent contradictions of Article 2(4) which in my view are only apparent –  that the Council’s powers and the right of self-defence “are not ‘exceptions’ to the prohibition“ but “instead instances that are simply not covered in the first place“ [see Patrick Butchard, Back to San Francisco: Explaining the Inherent Contradictions of Article 2(4) of the UN Charter, JCSL, (2018), Vol.23, No 2, 229-267 at 231] is incapable of successfully countering the prohibition’s  subsequent expansionist interpretation and application.

The notion of humanitarian intervention “poses the greatest challenge to the prohibition“ because it seeks to “restrict the prohibition’s reach on the basis of subjective assessments“ (p. 95). The  2005 World Summit Outcome attempt to partly remedy this major defect was in vain, as amply illustrated by subsequent state practice with or without Security Council authorisation (pp. 98-100).

O’Connell’s core argument that  “that the prohibition “ cannot be transgressed in the attempt to advance another norm, even another peremptory norm “ is (pp. 13, 94) is a valid one and welcomed but where do we find the moral and legal reasons for this prohibition‘s supreme position among jus cogens norms? Is the prohibition’s “existential” role for the international legal order (p. 54) higher? May the right of life of every human be called in as an explanation: probably not as it is “a norm increasingly being discerned as jus cogens “,  (p. 256) but possessing merely an “intrinsic superiority” (p. 77) as other existing ones? Perhaps the corresponding collective right to survival for mankind in times of WMD would qualify?  

The prohibition on the use of force “creates the most important restriction on the Security Council“(p. 106) a point of law “rarely if ever discussed“(p. 106), hence the need to re-emphasize the legal framework around Council action (p. 141) in Chapter 3.

Express authorization of  “national military action regardless of Article 43 agreements” is “appropriate in limited , emergency situations” (p. 118)  and on condition that the inherent principles are being complied with by both the Council and the States concerned (Chapter 3) . Although  the author accepts that the Council’s “ legal right to do so is unquestioned” (p. 118) – as such power forms an integral part of the prohibition (p. 145)  – it is not entirely clear whether such authorization can be given for humanitarian purposes: it would rest on a weak basis (p. 119) and constitute an expansion of Council authority beyond the narrow exceptions of the peremptory norm (p. 146). The Council should rather respond by authorizing alternative action “short of a use of force “(p. 147).

A critical review of the most relevant actions by both the Council and Member States, involving an ever greater use of force, also by UN peacekeeping missions, clearly demonstrates that force is not effective for achieving for instance protection of human rights (Chapter 3 and p. 139). The point made that “failing to adhere to the law governing resort to armed force has been linked to failure in accomplishing the very purpose of using force “(p. 144) perhaps deserves further debate and data. 

Chapter 4 deals with Article 51,  the relevant “natural and positive law provision” (p. 167) on self-defence, providing an exception to the prohibition (p. 169) of which it is “ an integral part “ (p. 154) or more precisely an exception to the Council’s unique “authority to authorize uses of force “ (p. 171), itself being an exception to Article 2, 4 (p. 172).  

Whereas an expansionist approach takes self-defence as a permissive right (p. 169) , a good faith interpretation “ will not result in limiting the reach of a jus cogens norm “ (p. 171); on the contrary, it implies a duty of abstention and restraint even in cases where the threshold of self-defence has (not) been reached (p. 177).  Moreover, the inherent – pre-Charter principles of necessity, proportionality and attribution do apply unreservedly as reaffirmed by the International Court of Justice (pp. 180-183).

Reprisals,  punitive and pre-emptive attacks are illegal given the defensive purpose of Article 51 (pp. 158, 172-173) while its restrictive interpretation does not permit military actions around arms control (pp. 186-194 ) rescuing nationals (pp. 194-197) and the fight against terrorism (pp. 197-204) . 

Additional challenges “to the logic of jus cogens with its presumption of peace “(p. 186)  are coming from armed intervention upon invitation – where “lack of criticism or acquiescence (on the part of the SC) is not the same as authorization “(p. 209) – and from the use of force in the exercise of an alleged right of rebellion.  

The restrictive effect of the pre-Charter belligerency rule has been steadily in decline not only to the point of States showing  “little sense of restraint“ (pp. 225-226) but even substituting actual consent by the “unable or “ unwilling “ argument (p. 227). Although internal conflict may constitute a threat to international peace and security bringing it within the Council’s jurisdiction (p. 232) it does not entail an expansion of its power to authorize military force (pp. 232-233).

While the author first posits that the prohibition merely “restrict(s) the right to violent rebellion “ (p. 235) she then rules it out as it  “ conflicts with the peremptory norm …” (pp. 237, 253 and 257) which applies to states and non-state actors alike (p. 254) and the restraints of which “may not be relaxed“ (p. 258).  International law is no more neutral to rebellion if it ever was (p. 255) and “the duty to respect the right to life renders (armed) rebellion unlawful in a way nearly equivalent  to the prohibition on the use of force“ (p. 254, emphasis added ) .

International Dispute Resolution

In her final Chapter the author considers ways to revitalize the process of international dispute resolution. The prohibition on force is interconnected (p. 266)  with a Charter-based and customary law obligation to peacefully settle their disputes , they do “form a unit “ (p. 268) and the intrinsic adversarial nature of the use of force should be abandoned when resolving a dispute (p. 264) , in favour of looking at it through the prism of theatre (pp. 283, 289-294). [See also Andre Bianchi’s fascinating contribution International Adjudication, Rhetoric and Storytelling, JIDS (2018) Vol. 9, 28-44.].

In my view, the “obligation to enter into good faith negotiations upon request of one state to another“  is more than just “emerging” (p. 283) : the process of negotiations may indeed be governed by “few, if any, rules beyond good faith “ (p. 268) but states are well advised to properly take into account the existing acquis jurisprudentiel  of the International Court of Justice. [see K.Wellens, Some Reflections on Good Faith during Negotiations in Recent ICJ Cases, 23 SYBIL (2019)), 31-69.]

It is a forceful argument that at the institutional level  the jus cogens norm “creates the most important restriction on the Security Council“ (p. 106) entailing “in some cases “the legal obligation to find alternatives to authorizing armed force “ (p. 149, emphasis added),  more in line with the expectations at San Francisco that the Council would “devote most of its time to the peaceful settlement of disputes“ (p. 113). In fact the Council indeed “has done almost nothing to promote dispute resolution “that is “beyond encouraging parties to negotiate or to engage with a mediator” (p. 274).


In her conclusion Mary Ellen O’Connell reaffirms the three propositions at the heart of her study and corresponding to the three components of law namely theory, substance and process (16). : “ a persuasive theory of international law for peace includes natural law, positive law, and process law components” (p. 297); the “core provision of the international legal regime of peace” (p. 298)  is the jus cogens prohibition on the use of force  permitting no derogations and disputes may be peacefully resolved through legal process (p. 302).

Almost nine decades ago Sir Hersch Lauterpacht has pointed out that modern international law “has neglected to find a legal foundation for the so-called pacifism which it has relegated to the domain of morals and sociology“ (as cited at p. 304) . That is precisely what Mary Ellen O’ Connell  – by “re-incorporating natural law theory into mainstream thinking “ (p. 81) – has achieved in her brilliant study : It is a timely publication as the “ decades of ever thinner arguments justifying the use of force may have reached the vanishing point “ (at p. 155, note 17).

Although the dominant view is that the subsequent objector rule does not exist [see James Green, The Persistent Objector Rule in International Law, OUP, 2016, at 150], state practice in relation to the prohibition indicates otherwise. It is true that “states almost never try to remain exempt from peremptory norms“ [Green, at p.279]  but  state practice dealt with in this book has certainly brought to light the rather persistent, ingenuous and sophisticated manner in which subsequent objectors operate towards the prohibition .

These efforts do not target the very existence of the peremptory norm but its applicability ratione materiae to  situations and circumstances allegedly unforeseen when the norm came into existence. In this sense we can discern  a ‘ variation’ of the more traditional persistent objector rule – which finds its legal basis in “the voluntarist notion of state consent“ [Green, at p. 71] –   the intended scope of which is ratione personae [Green, at p. 276].

It is a beautiful, multi-layered academic page-turner, passionately written in a seductive style from one chapter to the next one,  providing an holistic analysis and displaying an admirable knowledge of culture, history , theory and philosophy of law:  it is destined to become a ‘ livre de chevet ‘ in particular for legal advisers. Mary Ellen O’Connell has fully and skilfully exploited  the ‘power of imagination ‘as depicted by Philip Allott to whom she has dedicated her book. The book’s front cover perfectly symbolizes the instrumental role of aesthetic philosophy in the author’s analytical process throughout.

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