Major J. Jeremy Marsh*
The Study is a still photograph of reality, taken with great concern for absolute honesty, that is without trying to make the law say what one wishes it would say. I am convinced that this is what lends the study international credibility.1
In 2005, the International Committee of the Red Cross (ICRC)2
issued its 5000-page study, Customary International Humanitarian Law3
(the Study), examining what the U.S. military refers to as the law of war or law of armed conflict.4 The ICRC's press release accompanying the Study states that the organization took the process very seriously, spending more than eight years to research and consult with experts, and touts the project as "the most comprehensive and thorough study of its kind to date."5 Unfortunately, one need not spend much time reading the Study before concluding that there are serious flaws in its authors' method of determining what is and what is not customary international law (CIL).6 These methodological flaws led its authors to declare as rules of CIL what can only be described as lex ferenda (what the law should be) as opposed to lex lata (what the law is), diluting the credibility of the final product. This is unfortunate, as international and operational law practitioners certainly could have benefitted from an authoritative reference on customary international humanitarian law. The Study, however, fails to deliver because too many of its rules represent lex ferenda rules with insufficient evidence of state practice or opinio juris,7 the two requirements for the formation of CIL.8 Much of the Study, therefore, is not an accurate still photograph of reality, but rather, represents the ICRC's idealistic notion of what states should consider customary international humanitarian law.
Rule 45 of the ICRC Study, the main subject of this article, is a lex ferenda rule. This article will consider Rule 45 because it well illustrates the lex ferenda nature of the Study and is a good means by which to highlight the Study's main flaws. Rule 45 states that "[t]he use of methods or means of warfare that are intended, or may be expected, to cause widespread, long-term and severe damage to the natural environment is prohibited. Destruction of the natural environment may not be used as a weapon."9 The first part of this rule is taken from Articles 35(3) and 55(1) of Additional Protocol I to the Geneva Conventions (AP I).10 The Study recognizes the United States, France, and the United Kingdom as "persistent objectors"11 with respect to all or part of this rule.12 Based on their unorthodox analysis of state practice and opinio juris, the Study's authors nevertheless determined that the rule has ripened into CIL not only in international armed conflict,13 but also, arguably, in non-international armed conflict.14
Rule 45 is a paradigmatic example of the ways the Study's authors failed in this monumental and otherwise laudable project. Rule 45 showcases the Study's modern approach to CIL by elevating aspiration over empirical proof of actual state practice.15 The ICRC's discussion of the state practice that forms the basis for this rule is symptomatic of its faulty methodological approach to achieve a lex ferenda result. As Rule 45 demonstrates, the Study's authors assigned inordinate weight to verbal "practice" such as military manuals and resolutions of the U.N. General Assembly.16 In addition, Rule 45 demonstrates the Study's skewed understanding of the role of opinio juris. Its authors seem to conclude that if there is enough mention of the "rule" in military manuals and other questionable sources of verbal practice, then the opinio juris prong of CIL is also met.17 Finally, Rule 45 illustrates that the Study paid insufficient heed to two important CIL doctrines, specially affected states18 and persistent objection, in developing its rules of customary international humanitarian law.
Because a comprehensive analysis of the methodology used by the Study's authors could easily fill a book,19 this article will focus on Rule 45 as a lens through which one may assess the methodological approach employed by the Study. The article begins with a brief discussion of CIL. It is impossible for one to critically analyze the Study without some discussion of what CIL is, how it is formed, and why it is both important and controversial. After discussing CIL, the article will discuss the Study as a whole, particularly how the authors described their methodology. Then it will consider the authors' application of their stated approach to Rule 45, discussing first their description of the rule and second the evidence they provided in its defense. The article will conclude by analyzing the three principal flaws inherent in the authors' methodological approach to Rule 45: (1) marginalizing traditional CIL doctrines, (2) overemphasizing verbal practice of unclear and dubious weight, and (3) promoting lex ferenda. This analysis will demonstrate that not only Rule 45 but perhaps the rest of the Study's 161 rules should be viewed with suspicion by anyone seeking an authoritative statement of customary international humanitarian law.20
Customary International Law (CIL) and the ICRC Study
Customary International Law
No single definition of CIL exists. Article 38 of the Statute of the International Court of Justice (ICJ) lists custom as a source of international law, describing it as "evidence of a general practice accepted as law."21 The Restatement (Third) of Foreign Relations Law of the United States describes it as "resulting from a general and consistent practice of States followed by them from a sense of legal obligation."22 Both of these descriptions contain what the international community recognizes as the two elements of CIL: the "objective" or "material" element of state practice, and the "subjective" or "psychological" element of opinio juris.23
There is little disagreement over the basic description of CIL as stated above; there is a great deal of disagreement, however, over exactly how to characterize and consider its two elements.24 As one of the Study's authors, Jean-Marie Henckaerts, acknowledged, "the exact meaning and content of these two elements have been the subject of much academic writing."25 At the heart of debates over the elements of
CIL is what has been described as their inherent circularity.26 This quality becomes evident when considering that CIL is only law if the opinio juris element is met, meaning states believe it is the law.27 But why would a state believe something is the law unless the law already contained the required sense of legal obligation?28 "So it appears that opinio juris is necessary for there to be a rule of law, and a rule of law is necessary for there to be opinio juris."29
Another controversial issue associated with CIL formation is one of proof. What suffices as evidence of state practice? How do we determine what states recognize as opinio juris? As will be seen, the Study's answer to these questions is to consider a wide variety of sources, including both physical and verbal acts of states, when analyzing state practice and opinio juris. The approach the Study's authors used, however, tends to conflate the two elements; if there are enough sources of physical and especially verbal "practice"-the sources cataloged in Volume II of the Study-then a state is deemed to believe that the "custom" is in fact legally obligatory.30 To follow this approach is to stray from CIL orthodoxy, which requires a separate showing of general and consistent state practice and opinio juris.31
The state practice element of CIL requires generality and consistency of practice between states and is the element upon which CIL traditionalists tend to focus. 32 The traditional approach to CIL
emphasizes empirical, objective proof of state practice over normative statements, which may or may not establish what states collectively believe the law is or should be.33 This approach is empirical, objective, and inductive: custom is derived from specific instances of state conduct.34 What is interesting about the ICRC Study is that it labels its evidence, almost all of which is statement-based rather than physical, as state practice.35 It almost seems as if the Study's authors are cloaking their statement-based, modern approach to CIL in the language of tradition, perhaps to be seen as being more traditional in their approach to CIL formation than they actually are.
Rooted in the notion of state consent,36 the opinio juris element of CIL requires states to accept the practice as a positive legal duty for it to become CIL,37 and is the element upon which modernists tend to focus. The modern approach to CIL formation-the one actually employed by the Study's authors-focuses on normative statements, not acts.38 As such, the modern approach is viewed as emphasizing opinio juris over state practice.39 Under this approach, rules may be deduced from statements of rules, such as treaties40 or the declarations of international forums, rather than deduced from specific instances of state conduct.41
The modern approach is therefore the one that gets criticized for being a statement of lex ferenda, what its proponents wish the law would be, as opposed to lex lata, what the law actually is.42 Its concern is substantive normativity rather than descriptive accuracy, which is the concern of traditionalists.43
Identifying proof of opinio juris is problematic because determining when a state subjectively believes it is obligated to follow a rule of law is difficult if not impossible.44 Therefore, one must attempt to cull belief from the actions and statements of...