Daniel Costelloe's monograph is a recent addition to the current, rather lengthy list of literature involving the effects of peremptory norms in international law. It covers a wide variety of issues.

Costelloe acknowledges that the concept of peremptory norms is seen as giving expression to international public order (public policy, ordre public) with which many national legal systems are familiar, but claims that there is little need for the term ‘public order’, as the adjective ‘peremptory’ sufficiently expresses community interest behind the relevant norms. Moreover, further down the road of legal technicality ‘the term's usefulness quickly recedes’. However, there must be a reason why leading thinkers on this subject – such as Lord McNair, Sir Hersch Lauterpacht, Humphrey Waldock, Theodor Meron and John Dugard – have endorsed the concept of the inherent connection between jus cogens and international public order (public policy).Footnote ¹ The principal reason for this connection is to ensure that the concept of jus cogens possesses some analytical integrity, which ensures that the link between the factors that reinforce it and its normative consequences is not lost or neglected, as well as to provide analytical robustness, which ensures that the concept cannot be twisted and bent in response to the political and ideological demands of the day.

One may guess that the reason for the objection of the author of this monograph to the well-established tradition of connecting jus cogens with public policy is precisely his opposition to the analytical integrity and robustness of the concept of jus cogens. The author asserts that as the International Court of Justice (ICJ) indicated in the Jurisdictional Immunities case,Footnote ² ‘[e]ach consequence [of peremptory norms] requires an independent basis and cannot merely be inferred’ (pp 51–53). It is then suggested that ‘[t]he principal relevance of a norm's “peremptory” character in practice primarily stems from the particular consequences to which certain primary norms give rise’ (p 52). This suggestion is misleading, because the relevance of a norm's peremptory character follows not from its particular consequences but from the principle of non-derogability of jus cogens, according to which every single primary norm that can be identified as peremptory generates certain consequences. In other words, primary norms do not themselves determine their own consequences: the general doctrine of jus cogens, centred on the principle of non-derogability, determines those consequences for all such norms. Against this background, the suggestion that ‘[t]he specific consequences of peremptory norms in international law developed haphazardly and out of State practice’ (p 53) is similarly open to doubt, because state practice as such is subject to the regulatory and sanctioning effect of jus cogens. It may contain useful instances of how the doctrine of jus cogens develops, but it does not control its development.

The scope of the United Nations (UN) Security Council's powers is another area that raises the relevance of jus cogens. The author suggests that ‘[l]imits to the Security Council's powers are primarily political rather than legal’ (p 140). Reliance is then placed on Judge Schwebel's approach in Lockerbie (pp 139–40), which overlooks the fact that Judge Schwebel was in the minority and the Court in fact performed what he regarded to be judicial review of Security Council resolutions.Footnote ³ The author's position is not entirely compatible with the fact that the Security Council is a creation of law, its powers are invariably those that are delegated to it through the treaty instrument, the UN Charter.Footnote ⁴ This very basic fact is already in contradiction with the author's claim referred to above. Moreover, the ICJ has repeatedly held that the opposite is the case – as, for instance, in the 1948 Admissions opinionFootnote ⁵ and the 1971 Namibia opinionFootnote ⁶ (and the same approach was endorsed in an important passage on that subject by Judge ad hoc Jennings in Lockerbie, addressing the scope of the Security Council's political discretionFootnote ⁷). Moreover, the decision of the International Criminal Tribunal for the former Yugoslavia (ICTY) Appeal Chamber in Tadić Footnote ⁸ has, in the context of judicial review, clearly rejected the view that the Security Council is free of legal limitations.

In relation to the impact of jus cogens on state responsibility and state immunity, Costelloe's analysis does not reflect the content of Article 41 of the International Law Commission's (ILC) Articles on State responsibility (p 245). The key relevance of the latter provision is to prevent the legitimisation of situations created as a consequence of serious breaches of peremptory norms, not simply to provide that such breaches are unlawful or that states are responsible for them. State immunity, resulting in the lack of remedies with regard to serious human rights violations, at times generates impunity. Costelloe argues that ‘a conflict [between jus cogens and state immunity] could only arise if the breach of an obligation under a peremptory norm created a specific obligation to try alleged offenders or to make available certain civil remedies to individual claimants’ (p 245). However, if that were the correct position, there would be no need for any duty of non-recognition to be stated in relation to breaches of jus cogens at all. Those ‘specific obligations’ would be primary obligations themselves, creating states' rights and obligations in the manner in which any and every primary norm of international law creates them. Precisely that situation would be characterised by the absence of a conflict between state immunity and jus cogens. Indeed, in such a situation there would be no need to speak of jus cogens at all. It would be a conflict between that discrete and specific obligation and state immunity. More generally, moreover, the doctrine of jus cogens is not at all about the existence or content of discrete obligations that support the primacy of jus cogens. It is instead about outlawing derogation from a peremptory norm even if nothing else in the international legal system conflicts with the outcome that such a derogation purports to achieve. This is why Article 41 of the ILC Articles was adopted in its current shape, focusing on non-recognition of situations arising as a consequence of breaches of peremptory norms, and thus emphasising the link between the norm originally violated and the conduct subsequently required. Its purpose and scope relates to non-recognition of situations created through the breaches of jus cogens norms. It is hardly about primary norms, whatever their content and requirements may be. It is instead about the breach of a primary norm of jus cogens imperatively leading to the duty not to recognise the situation created through that breach.

All the above draws adversely on the approach of Lord Hoffmann in Jones v Saudi Arabia, cited by the author (p 259), that ‘the United Kingdom, in according state immunity to the Kingdom [of Saudi Arabia], is not proposing to torture anyone. Nor is the Kingdom, in claiming immunity, justifying the use of torture’.Footnote ⁹ As a consequence of this approach, the current situation in English common law is that it does not endorse the primacy of jus cogens over immunities in civil proceedings. Moreover, the position upheld in Jones (and earlier in Al-Adsani Footnote ¹⁰) is not about any single or one-off situation. Instead it establishes, on the domestic legal plane in the United Kingdom (UK), a continuously and prospectively operating legal position as between the UK and states such as Kuwait or Saudi Arabia, consisting of the derogatory deal between those states under which there is – implicitly but rather very effectively – an agreement that should any British national or foreign national be tortured in such states, the UK will not in the future afford to them any judicial remedy against the torturing state. Therefore, contrary to Lord Hoffman's approach in Jones, the House of Lords has in effect proposed and, for the time being, secured the position that in the bilateral relations between the UK and those states, torture will not attract any consequences of internationally wrongful acts – in other words, torture will be treated as lawful. This is precisely the derogation from jus cogens in the sense that, with regard to a particular subject matter such as torture and immunities, the relevance of jus cogens in bilateral relations as between the UK and those states is entirely absent.

The author's analysis does not focus sufficiently on arguments developed in the literature regarding jus cogens on the doctrinal position that differ from the author's own position. The book contains no sufficient consideration of literature that deals with the relationship between jus cogens and state immunity from a perspective other than that to which the author himself subscribes. In the material period of the judicial handling of this issue, several authors, such as Riccardo Pavoni and Carlos Esposito, have criticised the ICJ's approach in Jurisdictional Immunities or proposed an approach that differs from that of the ICJ.Footnote ¹¹ Other work that should have been addressed more intensively includes that of Antonio Cassese and Enzo Cannizzaro, and well as Asif Hameed's recent work.Footnote ¹² Moreover, Chapter 7 of the book repeatedly cites the article published by Zachary Douglas, yet does not deal with the fact that the analysis by Douglas of the relationship between jus cogens and state immunity in that article is far more receptive to, or far less dismissive towards, the impact of jus cogens in this area than is Costelloe's own reasoning.Footnote ¹³ The same could be said with regard to the treatment of some judicial decisions. For instance, the United States (US) case of Siderman, which the author briefly considers (p 279), suggested a more nuanced position than that upheld by the author. The Court did actually admit the primacy of jus cogens over immunities under international law, yet the Foreign Sovereign Immunities Act (FSIA) had to be applied in domestic legal proceedings over and above international law, and immunity subsisted on that very basis. As far as international law was concerned, the Court said that ‘[a]s a matter of international law, the Siderman argument carrie[d] much force’. Then, as the Court reasoned, ‘[i]nternational law does not recognize an act that violates jus cogens as a sovereign act. A state's violation of the jus cogens norm prohibiting official torture therefore would not be entitled to the immunity afforded by international law’.Footnote ¹⁴

Reference is then made to the ICJ's opinion in Germany v Italy that FSIA amendments made in 1996 are outliers (p 267). This, however, is contradicted by the fact that since the ICJ's judgment on Jurisdictional Immunities was handed down, both Canada and the US have, time and time again, amended their legislation in a way that cannot be reconciled with the ICJ's approach. Thus, state practice increasingly goes against the ICJ's position.Footnote ¹⁵

In some places question-begging propositions from judicial practice are acknowledged but not dealt with, nor are their implications confronted. The author states that ‘[i]mmunity … is a procedural issue, as the International Court repeatedly underlined in Jurisdictional Immunities, and not a question concerning the merits’ (p 257). This suggestion, however, overlooks an obvious fact that the proceedings in Germany v Italy dealt with the merits of the case, with substantive claims by Germany as to whether Italy's conduct in relation to Germany had violated obligations of substantive conduct arguably owed by Italy to Germany. A cliché that immunities are ‘procedural’ is often used in literature as well as judicial practice, yet that very same case of Germany v Italy dealt with immunities as substantive obligations that Italy arguably owed to Germany on the basis of primary rules of international law relating to the conduct of states.Footnote ¹⁶

A short review like this cannot deal with all the issues raised in Costelloe's monograph. However, the rather limited view of jus cogens that the book favours is not as firmly established as might be expected. Italian, Swiss and American courts have distanced themselves from the ICJ's approach on this issue.Footnote ¹⁷ The equation of immunity with impunity endorsed by both Jones v Saudi Arabia and Germany v Italy is both analytically incoherent and morally suspect for it to be able to carry the ground indefinitely.