BOOK REVIEWS Third-Party Countermeasures in International Law. By Martin Dawidowicz. Cambridge: Cambridge University Press, 2017. Pp. xxiv, 431. Index. doi:10.1017/ajil.2018.101 Martin Dawidowicz’s monograph examines the concept of third-party countermeasures in international law, also known as collective, solid- arity, or general interest measures. The author, a lecturer in public international law at the University of Oxford, defines a third-party coun- termeasure as an otherwise unlawful act of a peaceful charac- ter taken by a State other than an injured State in response to a breach of a communitarian norm owed to it (as defined in Article 48 [of the Articles on State Responsibility adopted by the International Law Commission (ILC) in 2001 (ARSIWA)]) in order to obtain cessa- tion and reparation. (P. 34) 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 geno- cide, slavery, and torture, and those that are owed to a group of states, such as under a multi- lateral treaty regime (erga omnes partes). 1 In prac- tice, these measures may take various forms, including coercive action, trade and arms embar- goes, 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 coun- termeasures or the enforcement of communitar- ian norms in a decentralized legal order, 2 it is the first one to focus entirely on state practice con- cerning 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 prac- tice 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 prej- udice clause in ARSIWA Article 54. 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 con- troversial 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 countermea- sures, was “limited and rather embryonic.” 4 This led the Commission to conclude in 2001 when adopting the ARSIWA that: The current state of international law on countermeasures taken in the general or 1 For ease of reference, both erga omnes and erga omnes partes obligations will be referred to here as com- munitarian norms, to the extent that they concern the international community as a whole or in part. 2 See, e.g., CHRISTIAN J. TAMS, ENFORCING OBLIGATIONS ERGA OMNES IN INTERNATIONAL LAW (2005); SANTIAGO VILLALPANDO,L’ÉMERGENCE DE LA COMMUNAUTÉ INTERNATIONALE DANS LA RESPONSABILITÉ DES ÉTATS (2005); MATHIAS FORTEAU,DROIT DE LA SÉCURITÉ COLLECTIVE ET DROIT DE LA RESPONSABILITÉ INTERNATIONALE DE L’ÉTAT (2006); DENIS ALLAND, JUSTICE PRIVÉE ET ORDRE JURIDIQUE INTERNATIONAL: ÉTUDE THÉORIQUE DES CONTRE-MESURES EN DROIT INTERNATIONAL PUBLIC (1994); LINOS-ALEXANDRE SICILIANOS,LES RÉACTIONS DÉCENTRALISÉES À L’ILLICITE (1990); FRÉDÉRIC DOPAGNE,LES CONTRE-MESURES DES ORGANISATIONS INTERNATIONALES (2010). 3 ARSIWA Article 54, entitled “Measures Taken by States Other than Injured States,” reads as follows: “This chapter does not prejudice the right of any State, entitled under article 48, paragraph 1, to invoke the responsibility of another State, to take lawful mea- sures against that State to ensure cessation of the breach and reparation in the interest of the injured State or of the beneficiaries of the obligation breached.” 4 ARSIWA Commentary to Article 54, para. 3. Copyright © 2019 by The American Society of International Law 200