Editor’s Note: This post is the latest in Just Security’s 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 VanLandinghamGary BrownDavid Glazier, and Joshua Berry

Thanks to Sean Watts and Eric Jensen for organizing, and Just Security for sponsoring, this discussion on the recently released Department of Defense Law of War Manual. I echo previously expressed appreciation for the effort that went into the manual’s drafting, revision, and publication. The manual represents a much needed and long overdue step by DOD. That said, I question how well the manual accomplishes its stated purpose of “provid[ing] information on the law of war to DoD personnel responsible for implementing the law of war and executing military operations.” I say that because what military commanders and their legal advisors needed (and wanted) was for DOD to provide specific guidance as to the law of armed conflict (LOAC) applicable to US forces during non-international armed conflict (NIAC) as a matter of DOD policy. This the manual largely failed to do in several important areas. I’d like to focus on two, customary international law (CIL) and detention. I first highlight the legal gap the manual needed to fill and then explain why the manual’s guidance on CIL and detention is too general to meaningfully inform those executing military operations.

The legal gap is well known – there is an inverse relationship between the type of armed conflicts occurring and the amount of LOAC which applies as matter of law. Since WWII the overwhelming majority of armed conflicts (90% or more) have been NIACs for which there is little treaty law, most prominent of which include Common Article 3 and the handful of operative articles of Additional Protocol II, while there is a relative wealth of law (Geneva Conventions and Additional Protocol I) applicable in international armed conflicts (IAC), the kind of armed conflict infrequently occurring.

Thought of another way, combining US military operations in Afghanistan and Iraq, the US was involved in IACs against the governments of those countries for a couple of months. The US has been involved in NIACs in those countries for a total approaching two decades. Short of a new treaty or convention, the legal deficit in NIACs can be mitigated by some combination of (1) applying IAC law in NIAC as a matter of policy and (2) CIL. But to have military operational utility, which IAC law and CIL applies needs to be clear. That clarity should come from DOD and the manual would seem an appropriate method of dissemination. But on CIL, and at least in parts of the detention chapter, the manual speaks in generalities, providing “guidelines” and “factors” for the reader to apply and determine that which the manual should be providing to meet its stated purpose. The manual should be answering questions on CIL and detention, not asking them.

To better understand what was needed from the manual, consider a previous DOD attempt to provide policy guidance. A 2006 directive (recertified in 2011) announced “[i]t is DoD policy that: []Members of the DoD Components comply with the law of war during all armed conflicts, however such conflicts are characterized, and in all other military operations.” The directive defined the law of war as “all international law for the conduct of hostilities binding on the United States…and applicable customary international law.” But what, specifically, is that international law? And what is the applicable customary international law?

Nine years later we have the DOD LOW manual, which partially addresses, but doesn’t answer, the question the 2006 Directive raised – what specific LOAC is the US applying as a matter of policy while engaged in NIACs?

On CIL, the manual acknowledges on page 1,018 that “many of the rules applicable to non-international armed conflict are found in customary international law.” But rather than list what those rules might be, even as matter of policy, the manual provides guidelines which “may be helpful in assessing” the CIL applicable to NIAC. Providing multiple interpretative guidelines and directing the reader to assess which CIL rule may apply is not particularly helpful to those executing military operations. And reasonable military legal advisors might well apply those guidelines differently, problematically yielding different answers as to applicable CIL.

Within NIACs, one of the most challenging issues military commanders and their legal advisors face is detention. This may be the area where DOD guidance was most needed. In the manual’s NIAC chapter, detention warrants one page and the important issue of non-punitive detention one paragraph. And the significant claim that such detention “may be conducted on a variety of legal theories under international law” is supported by a single reference to British practice during the 1950s Mau Mau rebellion. The manual’s chapter on detention provides some useful information, but is only 22 pages out of a 1200 page manual, providing neither sufficient depth nor detail. (By contrast, the POW chapter is 119 pages long and unhelpfully detailed, providing a breakdown of how many Swiss francs different ranked POWs should receive in advance pay (while acknowledging that no country has ever implemented such an advance pay plan) and listing the antiquated requirement of access to telegraph.)

The detention chapter states that “it may be appropriate to apply the principles of the [Geneva Conventions], even when the relevant provisions do not apply as a matter of law.” Yet the manual doesn’t clarify what those principles are. Finally, the detention chapter also briefly discusses the process by which the US reviews security detention. But it does so in generalities and through references to the Copenhagen Process. This is particularly perplexing as DOD has developed a Periodic Review Secretariat and a process through which “file” and “full” reviews of security detainees are conducted at designated intervals. Not only does the manual not include (or even mention) that information, it states in generalized language that there is no fixed requirement for the frequency of reviews and provides a list of factors for readers to answer detention review questions DOD has elsewhere already answered.

The result is a manual that provides the least guidance in areas where it may be most needed, CIL and detention. The manual’s lack of specificity on what LOAC applies as matter of policy to US forces during NIACs may prove usefully defensible to critique while preserving a kind of strategic flexibility. But what the manual doesn’t do as much as it could – and should – is usefully and specifically inform the DOD personnel responsible for implementing the law of war and executing military operations.