Martin Dawidowicz's monograph examines the concept of third-party countermeasures in international law, also known as collective, solidarity, or general interest measures. The author, a lecturer in public international law at the University of Oxford, defines a third-party countermeasure as

Third-party countermeasures remain one of the most complex and challenging issues in the implementation of the law of international responsibility in respect of breaches of obligations owed to the international community as a whole (erga omnes), such as the prohibitions of genocide, slavery, and torture, and those that are owed to a group of states, such as under a multilateral treaty regime (erga omnes partes).Footnote ¹ In practice, these measures may take various forms, including coercive action, trade and arms embargoes, suspension of membership in international and regional organization, travel bans applied to senior officials, and asset freezes.

While this is not the first monograph on countermeasures or the enforcement of communitarian norms in a decentralized legal order,Footnote ² it is the first one to focus entirely on state practice concerning third-party countermeasures and on whether such measures have a solid foundation in international law. Dawidowicz's monograph is an analysis of very high quality—it is current, balanced, and evidently based on comprehensive research—and it certainly advances the state of the art of the scholarship on the subject. Through his comprehensive review of the practice of states in this area, Dawidowicz seeks to demonstrate that third-party countermeasures are now part of customary international law, questioning thereby the wisdom of the ILC's choice of adopting no more than a without prejudice clause in ARSIWA Article 54.Footnote ³

However, as Dawidowicz has acknowledged, ARSIWA Article 54 only refers to lawful measures that can be taken by states other than injured states. The question is of course much more controversial insofar as otherwise unlawful measures are concerned. At the time of codification of the ARSIWA, the ILC considered that the practice of otherwise unlawful measures by other than injured states, i.e. of third-party countermeasures, was “limited and rather embryonic.”Footnote ⁴ This led the Commission to conclude in 2001 when adopting the ARSIWA that:

As noted above, Dawidowicz's monograph aims to challenge the continuing validity of the ILC's assessment. But first, are these otherwise unlawful unilateral measures, purportedly taken in the collective interest, conceptually even part of the law of international responsibility? Should they be part of the law of international responsibility? Are these not simply enforcement actions or elements of private justice in a decentralized system which aims nonetheless at a certain degree of legality and public order? More fundamentally, does the “without prejudice” character of ARSIWA Article 54 not militate in favor of a view that any such countermeasures—even if they have a legal foundation in the international legal system—find their source outside the mechanics and logic of the law of state responsibility?

Responsibility in international law, as codified by the ILC, extends to “all forms of new legal relationship” arising from the commission of an internationally wrongful act

In light of the above, can we speak of a third-party countermeasure as a new legal relationship flowing from the breach by another state of a communitarian norm? And if so, how can we ensure that such a countermeasure would not be open to abuse if it were to become instrumentalized in the hands of the few powerful states that would take on the role as a “policeman” in the interest of all? These are indeed some of the core questions that Dawidowicz addresses in his monograph (p. 3).

With the progressive recognition in international law that certain core obligations create a legal interest for all states in their protection, states have had to “frequently react [to the breaches of such obligations] by way of third-party countermeasures” (id.). The question is thus far from a purely theoretical one and the timing of the book is particularly opportune, given that we have witnessed numerous examples of third-party countermeasures in the last decade alone, including the measures taken by the Western states against the Russian Federation in reaction to the events in Crimea in March 2014, the measures taken by the EU, the United States, and the League of Arab States against Syria since the beginning of the armed conflict in 2011, and the measures taken by Switzerland and the United States against Libya in 2011—all in response to what the states concerned viewed as serious breaches of communitarian norms. However, these and other examples raise a host of unresolved issues as to the conditions, both substantive and procedural, that would apply to the adoption of third-party countermeasures, and more fundamentally to whether these measures were adopted out of a sense of legal obligation or merely for political reasons.

The author's review of state practice in respect of third-party countermeasures, an issue that has indeed received insufficient attention in scholarship (p. 15), may at first have seemed like a relatively straightforward exercise. However, that is not at all the case. The identification and analysis of practice in this area is particularly difficult for two principal reasons. First, states rarely if ever describe the measures they take in response to a breach of a communitarian norm as third-party countermeasures. Second, the exercise is complicated by the scarcity of judicial pronouncements, which in any event only peripherally touch on the core questions raised by the author. As Dawidowicz meticulously demonstrates, these decisions have focused on the identification of an obligation erga omnes, the standing and legal interest of states to invoke responsibility for breaches of obligations erga omnes, and the ability of directly injured states to resort to countermeasures, i.e. bilateral measures and not third-party countermeasures (Chapter 2). Notwithstanding these methodological challenges, as noted above, the author has succeeded in providing a systematic, balanced, and comprehensive analysis of state practice (Chapter 4). Dawidowicz has also successfully questioned the purpose and examined the potential risks of the increasing use of third-party countermeasures. Chapters 5 and 6 are by far the most stimulating as an analytical discussion of third-party countermeasures. The author discusses in considerable detail each of the main objections identified by the ILC when considering the subject of third-party countermeasures: (1) the absence of widespread and representative practice; (2) the absence of consistent practice; and (3) the absence of practice accepted as law (pp. 240–382).

However, the findings reached by the author may be challenged for the following two reasons, which in no way cast doubt on the quality and the importance of this study.

First, while the author attempts to convince the reader that third-party countermeasures are permissible in international law, such measures run a serious risk of undermining the system of collective security as is set out in Chapter VII of the UN Charter. The author concedes that this may indeed pose a problem but nevertheless dismisses this fundamental concern by positing that “practice provides only a handful of genuine examples of potential conflict” (p. 257). After examining the relevant instances of the parallel application of certain Security Council measures and third-party countermeasures, the author concludes that an “enforcement action under Chapter VII of the Charter does not per se end any entitlement to adopt third-party countermeasures. A Security Council resolution may certainly limit or even extinguish the entitlement to use third-party countermeasures in a given case, but this is largely a question of interpretation that is difficult to assess in the abstract” (pp. 261–62). The author appears to gain comfort by accepting that proportionality may act as a “substantive limitation on the use of third-party countermeasures in cases where the Security Council has also taken action” (p. 262). At the same time, the author states that “[t]he assessment of the proportionality of countermeasures is … ‘not an easy task and can best be accomplished by approximation’” (p. 347). However, the fact that such a normative conflict has not, in the author's view, arisen yet in practice cannot necessarily lead to the conclusion that the increasing use of third-party countermeasures is consistent with the core idea of collective security as set out in the Charter. As rightly pointed out by Sicilianos,

Second, the author has identified twenty-one examples of third-party countermeasures taken in the period from 1960 to 2016, which he argues demonstrate that a sufficiently generalized and consistent practice exists to conclude that they now are part of customary international law (Chapters 4 and 5, see in particular p. 242). The reader is left with the impression that each example of state practice has been analyzed through an intellectual process of exclusion, i.e. because there was no other legal basis that may explain the conduct adopted by third state, the conduct must then be considered to have been a countermeasure in response to a prior internationally wrongful act. The author is not alone in falling into this trap of deducing the existence of customary international law from a set of disparate actions, which fall concomitantly with the normative and political discourse of states. However, if there is one critique in this respect, it is that the author does not properly acknowledge this important methodological issue, with a few possible exceptions (see, for example, pp. 262–63).

Further, one can legitimately argue that some of these actions taken by states were based on sources of law outside of the regime of state responsibility, such as under primary norms of international law or on the basis of legal and policy considerations other than the existence of a breach of a communitarian norm. This is very likely the case of the measures cited by the author that have been taken by states which are members of regional international organizations, such as the EU (pp. 119–27). While the practice identified by the author is helpful, it is not always clear whether the actions of the state were necessarily taken in response to a serious breach of obligations erga omnes or erga omnes partes. In most of the twenty-one instances of practice identified, the author appears to acknowledge this issue by using qualified language, such as: “[t]heir actions may therefore be understood as third-party countermeasures” (p. 139; see also, for example, pp. 157, 235). As Paddeu has rightly observed, the examples cited by the author do not appear to contribute to the generality and consistency of practice necessary for the existence of customary international law.Footnote ⁸ This is the case of the practice of Latin American states and the Non-Aligned Movement. Even more critically, the author says little on the opinio juris that would convince the reader of the existence of customary international law on third-party countermeasures. The author appears to be aware of this fundamental weakness in his study as he concludes that “opinio juris may be somewhat obscure but it nevertheless exists” (p. 283).

Notwithstanding the remarks above, Dawidowicz's book makes an important contribution to the scholarship relating to the law of international responsibility, as has already been emphasized elsewhere.Footnote ⁹ First, as noted above, it presents a valuable analysis of state practice in respect of third-party countermeasures. Second, it considers both arguments in favor and against the legality of third-party countermeasures in international law as well as the means available to ensure that the availability of such measures is not abused. Third, it considers how the substantive and procedural conditions that apply to countermeasures might be extended to third-party countermeasures.

However, while the author acknowledges that “[t]he use of third-party countermeasures has clearly not resulted in an ideal or full level of compliance with communitarian norms” (p. 281), he still argues that their use may “send a ‘powerful signal’ that serious illegalities will not be tolerated” (p. 282) and that their “real effectiveness is best measured in contextual and incremental terms” (p. 284). This argument goes too far, in my view, as it essentially boils down to saying that deficiencies in the available institutional responses to violations of communitarian norms render lawful the ability in principle of any state to which an obligation is owed to take unilaterally coercive measures. This subverts the sanctity of international obligations and of the legal order as a whole rather than contributing to it. The risk of abuse by powerful states is far too great, as states appear to have recognized, for the instrument of third-party countermeasures to be considered as part and parcel of the international legal order. While Dawidowicz makes a persuasive argument that proportionality would be a sufficient limitation to avoid abuse (pp. 346–64) and that most countermeasures in any case have only been taken in practice in response to serious breaches of communitarian norms (pp. 269–70), that vision is too optimistic in my view in light of the current rapports de force in international affairs.

My criticisms of Dawidowicz's thesis and findings may be no more and no less than a reflection of the differing views that we evidently hold on the outer limits of the international legal order and the role that international responsibility plays in maintaining legality and the rule of law in international affairs. I remain convinced that the taking of unilateral countermeasures in response to breaches of communitarian norms risks diluting the function of the law of responsibility and rendering even more fragile the institutional framework of the international legal order.