Editor’s Note: Just Security is holding a “mini forum” on the new Defense Department Law of War Manual. This series includes posts from Sean Watts, Eric Jensen, Adil Ahmad Haque, Geoffrey Corn, Charlie Dunlap, Jr., John Dehn, Rachel VanLandingham, and Gary Brown, with more to come.

Previous commentators have examined specific provisions in the Defense Department’s (DOD) new Law of War Manual. I’d like to ask a more basic question about this curious publication: what authority should it have both within and outside the US military? We should be clear upfront that much of the manual’s substantive content is unexceptional, simply spelling out internationally agreed treaty rules. The issue is what weight is the manual entitled to regarding matters subject to dispute, particularly its unique views on the status of some customary international law obligations?

The world’s first entry in the law of war manual genre was the 1863 “code” drafted by Columbia professor Francis Lieber. Although knowledge of the rules of war was a core competency for professional soldiers, the Civil War saw a massive influx of volunteer officers direct from civilian life. Lieber thus pressed the US Army to let him to prepare “a little book on the Law and Usages of War” for their guidance. Army commanding general Henry Halleck (the author of an 1861 treatise on which Lieber drew heavily) personally edited the work to ensure its accuracy and comprehensibility before sending it to the White House for Lincoln’s approval. It was then distributed to the Army under cover of General Order No. 100.

By 1914, Geneva and Hague Convention development had dated Lieber’s work, so the Secretary of War approved a new “Rules of Land Warfare” manual issued as a serialized War Department document. It provided a concise summary of the law with shorthand citations to primary legal authority in the text. Following obscure 1917 and 1934 updates; a 1940 revision was issued over the signature of Army Chief of Staff George C. Marshall as field manual FM 27-10. The current iteration dates to 1956, with a single 1976 “Change 1” reflecting US ratification of the 1925 Geneva Gas Protocol. It thus fails to provide guidance about most significant legal developments of the last six decades, including a dozen relevant treaties (most notably the Additional Geneva Protocols of 1977), recent international criminal law jurisprudence, and the publication of several unofficial, but influential, legal manuals. 

The US Air Force has done little better. Its 1976 Air Force Pamphlet 110-31, “International Law – The Conduct of Armed Conflict and Air Operations” has been out of print for years and few officers or commentators even seem aware of its existence.

The US Navy has done the best job of the services with a periodically revised Naval Warfare Publication, “The Commander’s Handbook on the Law of Naval Operations,” (currently NWP 1-14M of 2007). It addresses both the law of the sea and law of war, providing straightforward explanations of applicable legal rules, although generally without reference to their source. Naval War College lawyers have produced several annotated editions, adding detailed citations for the benefit of those engaging in more rigorous analyses.

There is little doubt that a credible unified US law of war manual is badly needed. As noted, most US military personnel currently lack access to up to date guidance. The Navy manual capably addresses traditional maritime operations, but shortchanges the Marines and SEALs with respect to ground combat guidance. And it makes little sense to coordinate air campaign operations jointly yet have no common legal reference for targeting decisions!

Unfortunately the new DOD manual lacks essential characteristics that gave its predecessors credence. First, as a “manual” approved only by the DOD General Counsel, an individual outside the legal chain of command, it lacks any formal status familiar to our military forces. Every prior manual reflected chain of command approval and was issued as a recognized military publication type: general order, field manual, NWP, etc. As a warrior, I’d have no idea what the significance of this tome was – if I’d ever even see it; the absence of distribution guidance in the online version calls into question whether it will even be provided to operational units. If the Department of Defense intended this publication to be taken seriously by operational military forces, it should have undergone formal review within the actual chain of command and been issued as an actual DOD directive or Joint Publication.

Moreover, the manual lacks the clarity of its predecessors thanks to often obtuse prose, frequent cross references, unnecessary bulk, and verbose repetition. Although dissing the academic practice of “providing tangential information in footnotes,” a cursory flip through the pages shows that the manual’s ratio of body text to footnotes is on a par with the worst law review practice. In terms of clarity and practical utility, this manual can’t hold a candle to either its US predecessors, the UK Ministry of Defence’s 2004 Armed Conflict Manual, or unofficial modern volumes such as the HPCR Air and Missile Warfare and Tallinn cyberwarfare manuals.

There are many reasons why military personnel need law of war knowledge. As the manual’s foreword notes, compliance facilitates military success (a point typically overlooked by those fixated on “lawfare” as an enemy strategy). But US personnel also require guidance to avoid risk of criminal prosecution, whether by our own military, the Justice Department employing the War Crimes Act, enemies who might capture them, or foreign states exercising universal jurisdiction. Our troops thus deserve the best possible guidance on the internationally recognized rules governing conflict blessed by the US military commanders who make prosecution decisions, by the Department of Justice which could prosecute them domestically, and by the State Department which may have to justify their conduct to foreign states. This idiosyncratic volume by a few DOD lawyers with disclaimers about the views of these other entities does our military personnel a disservice.

Is the manual at least of value internationally; that is to say, can it be taken as an accurate indication of US opinio juris? I think not. US foreign policy is formed through an interagency process. To the extent any single entity could speak for the United States with respect to international law, it would be the Justice Department’s Office of Legal Counsel or the State Department’s Legal Advisor, not DOD. Tellingly, the critical 2006 US response to the International Committee of the Red Cross (ICRC) customary international humanitarian law study was jointly signed by the DOD General Counsel and State’s Legal Advisor. Core US complaints included allegations that the ICRC gave credence to state practice “insufficiently dense to meet the ‘extensive and virtually uniform’ standard generally required to demonstrate the existence of a customary rule,” that it gave too much weight to military manuals, and that it cited DOD publications that were not “authoritative statements of US policy and practice”. Even if DOD could unilaterally express US government views on opinio juris, it would be hypocritical to assert that this manual, which contains numerous cites to single instances of US conduct, or to earlier US manuals, merits substantial international weight. But it is the manual’s status as a unilateral DOD General Counsel product that ultimately undermines its utility both at home and abroad.

Our military badly needs an unified law of war manual, providing clear guidance approved by senior leadership, to our service personnel. Unfortunately this manual does not fulfill that need.