Tallinn Manual on the International Law Applicable to Cyber Warfare.

Author:Eichensehr, Kristen E.
Position::Book review

Tallinn Manual on the International Law Applicable to Cyber Warfare. Edited by Michael N. Schmitt. Cambridge, New York: Cambridge University Press, 2013. Pp. xix, 282. Index. $120, cloth; $58.99, paper.

In 2009, the NATO Cooperative Cyber Defence Centre of Excellence (NATO CCD COE) in Tallinn, Estonia, invited a group of independent experts--the International Group of Experts (IGE)--on the law of armed conflict to produce a manual on cyber warfare. The drafters, led by Michael N. Schmitt, who chairs the international law department at the U.S. Naval War College, included a mix of well-regarded practitioners, academics, and technical experts, as well as observers from NATO's Allied Command Transformation, U.S. Cyber Command, and the International Committee of the Red Cross. Over the course of several years, the IGE developed the Tallinn Manual on the International Law Applicable to Cyber Warfare. The Tallinn Manual provides a thorough and careful analysis of how the jus ad bellum and jus in bello translate to cyberspace, along with helpful descriptions of divisive issues that remain to be resolved through state practice and debate. Although the Tallinn Manual's reliance on the Western and NATO-centric perspectives of its drafters may hamper its acceptance in countries, such as China and Russia, that espouse very different visions for cyberspace, the Tallinn Manual offers an indispensable resource for scholars, practitioners, and policy makers.

The Tallinn Manual is designed to provide "some degree of clarity to the complex legal issues surrounding cyber operations" (p. 3) and, in particular, to describe "the applicable lex lata, that is, the law currently governing cyber conflict," not "lex ferenda, best practice, or preferred policy" (p. 5). The Tallinn Manual styles itself as a cyberwar incarnation of earlier nongovernmental codification or restatement efforts, including the San Remo Manual on International Law Applicable to Armed Conflicts at Sea (1) and the Manual on International Law Applicable to Air and Missile Warfare. (2) The introduction describes the Tallinn Manual as the product of an "expert-driven process designed to produce a non-binding document applying existing law to cyber warfare" (p. 1), and it takes pains to note that the Tallinn Manual is neither a NATO document, despite the sponsorship of the NATO CCD COE, nor a reflection of the official position of any state or organization from which the experts are drawn.

Following an introduction by Schmitt describing the project and its genesis, the Tallinn Manual sets out ninety-five black-letter rules and accompanying commentary. Rules in part I addresser ad bellum issues, such as sovereignty, state responsibility, the prohibition on the use of force, and self-defense, while rules in part II cover jus in bello issues, such as permissible targets, proportionality, occupation, and neutrality. Each rule was adopted by consensus among the IGE and is intended to "replicate customary international law" (p. 6), unless otherwise noted. Although the Tallinn Manual itself is a nonbinding document, it explains that to the extent the rules "accurately articulate customary international law, they are binding on all States, subject to the possible existence of an exception for persistent objectors" (id.).

The Tallinn Manual's ambitious scope and broad coverage of the jus ad bellum and jus in bello reflect a strong degree of agreement among the IGE. The agreement on specific rules builds on the IGE's consensus about a more foundational aspect of international law applicable to cyberwar, namely the IGE members' unanimous agreement that "general principles of international law appljy] to cyberspace" and rejection of the idea that "international law is silent on cyberspace in the sense that it is a new domain subject to international legal regulation only on the basis of new treaty law" (p. 13). (3)

While the rules on which the IGE agreed are very useful in advancing thought and debate about international law regarding cyberwar, more valuable still are the instances in which the Tallinn Manual frankly acknowledges disagreement within the IGE. The...

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