The Empire Strikes Back – Debating the Origins of the Customary Laws of War

In 2005, the International Committee for the Red Cross (ICRC) released a VERY long study on customary international humanitarian law. It is an impressive work, spanning more than 5000 pages, presenting the detailed and expansive views of an organization uniquely situated to know what rules have emerged binding states as a matter of custom, separate and apart from their treaty commitments under the laws of war. But, as John Bellinger alluded during his guest blogging stint with us, the ICRC study was not the last word on the subject. Late last year, Bellinger and DOD General Counsel, William Haynes, sent the ICRC a letter, providing the official U.S. reaction to the Study. You can now access it here. Regardless of whether you agree or disagree with U.S. views on the laws of war, this is an important letter. International lawyers should read it for at least two reasons.

First, read the letter on the merits. It records U.S. disagreement with some of the ICRC study’s general and specific conclusions. Thus, it rejects the study’s assertion “that a significant number of rules contained in the Additional Protocols to the Geneva Conventions have achieved the status of customary international law applicable to all States” including those that did not join the Protocols (e.g., the United States). The U.S. response also questions the ICRC assertion that “certain rules contained in the Geneva Conventions and the Additional Protocols have become binding as a matter of customary international law in internal armed conflict.” More specifically, the United States attaches to its letter a series of critiques of the ICRC’s characterization of rules on (i) respect due humanitarian relief personnel, (ii) the prohibition of anti-personnel bullets that explode in the human body, (iii) the right of states to vest universal jurisdiction in national courts over war crimes; and (iv) the very existence of a rule prohibiting methods or means of warfare causing widespread, long-term or severe damage to the natural environment. Here’s a taste of the U.S. views:

Since the United States engages in armed conflict more than other states (think Iraq, Afghanistan, Somalia), its views have obvious practical implications for the conduct of armed conflict. They may also effect how other states react to the ICRC study, and—more importantly—the content of customary international humanitarian law.

Second, read the letter for its methodology. Whether you agree with the U.S. letter (or the ICRC study) may well turn on when you would admit the existence of customary international law. Indeed, the U.S.-ICRC differences are fundamentally about method—how customary international law comes into existence. The exchange reveals many, if not most, of the on-going debates about the formation of customary international law.

Now, neither the United States nor the ICRC appear to challenge the traditional criteria for identifying a rule of customary international law – a consistent and uniform practice of some duration that states follow out of a sense of legal obligation (a.k.a. our namesake, opinio juris). Where they disagree is in the application of those criteria, specifically what constitutes state practice in the first place. The United States complains, for example, about how that the ICRC study undervalues contrary or “negative” practice and that of specially affected states (here, the United States appears to be asserting a some-are-more-equal-than-others approach to dictating the content of customary laws of war on the grounds that the U.S. practice should matter more, given its experience and frequent involvement in armed conflicts).

The treaty lawyer in me found the discussion of how treaties affect custom fascinating. The U.S. letter questions how the ICRC study can provide a more general formulation of the protection due humanitarian relief personnel than in the qualified protections available under the relevant treaties, which incorporate a state consent element absent in the ICRC formulation:

Despite the fact that these treaties clearly qualify State obligations regarding [humanitarian relef personnel on state consent, the ICRC rule] lacks any such qualifications. Because the practice of States Parties to treaties presumptively tracks their treaty prerogatives and obligations, we would expect that, to justify omission of these qualifications, the Study would have provided particularly strong evidence of State practice that was inconsistent with them. However, the Study simply concludes that “the overwhelming majority of practice does not specify this condition [of consent],” even after acknowledging that the protection of HRP under the Additional Protocols “applies only to ‘authorised’ humanitarian personnel as such.

The United States voices a similar objection about the ICRC inferring a customary right for national courts to assert universal jurisdiction over war crimes since states might infer that right from their treaty obligations rather than a more general customary rule.

The BIG difference between the United States and the ICRC, however, lies in the general question of what “counts” for state practice. Does the rhetoric employed by states and other actors (via military manuals, certain widely adopted U.N. General Assembly resolutions, NGO statements) qualify or—as the U.S. letter asserts—must practice turn more on an examination of what states actually do (or don’t do). In other words, does custom emerge from rhetoric or actual conduct? Of course, this is not a new debate, but one that’s plagued international lawyers for some time. It’s also a question courts frequently face. Indeed, one can see the judicial version of the US-ICRC debate in the contrasting views of custom expressed by the Supreme Court in Sosa v. Alvarez-Machain and Judge Kaufman’s views in Filartiga v. Pena-Irala.

Finally, on the question of opinio juris itself, the U.S. letter challenges the ICRC’s willingness to presume its existence when state practice is sufficiently dense: “Although the same action may serve as evidence both of State practice and opinio juris, we do not agree that opinio juris simply can be inferred from practice.” The U.S. view may actually find some support in the ICJ’s jurisprudence (see, e.g., Lotus, North Sea Continental Shelf and Nicaragua), which generally seems to require states seeking to establish a customary rule to provide affirmative evidence of opinio juris. The ICRC, in contrast, seems to follow the ILA’s lead and operate with a presumption of opinio juris in the face of state silence on whether conduct results from a sense of legal obligation or a non-legal basis (e.g., courtesy, political expedience, etc.).

Of course, as important as the U.S. views are on these issues, they are not definitive. As a result, it would be interesting to see if other states have articulated responses to the ICRC study, and, if so, whether they view it more favorably than the United States? Do readers know of any such reactions? Of course, I’d also be interested to see what readers think of the U.S. letter or the ICRC study that spawned it.