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, Gary Brown, and David Glazier, with more to come.

As evidenced by the posts on this blog and others, the new Department of Defense Law of War Manual has certainly given the academic community plenty to analyze. For those of us tasked with applying the law of armed conflict to military operations, the manual finally provides the Defense Department’s (DOD) concrete positions on a variety of topics (an easy example is the section on “Civilians Taking a Direct Part in Hostilities”). While Professor Glazier’s recent argument that some of these stated positions are not particularly useful is fair, one overlooked aspect of the manual’s helpfulness is its discussion on weapons law. The manual provides a needed update from the US Army’s Field Manual 27-10’s rather brief treatment of weapons, which is limited to two pages in Section III, Forbidden Means of Waging Warfare. In contrast, the weapons law section of the DOD manual covers nearly a hundred pages, consolidating law and policy previously scattered across numerous treaties and executive orders. While there are several portions of the weapons law section that are worthy of note (i.e., a rather lengthy discussion of the legality of serrated knife blades), I would like to focus on a heretofore overlooked shift in US policy on expanding ammunition or “hollow point” bullets and permitting their use in armed conflict.

Most of us educated at the US Army’s Judge Advocate General’s School left with some hard and fast rules regarding weapons that are unlawful, per se. For example, biological agents and poisons are always unlawful in war. These prohibitions arise from clear treaty obligations and there is no particular reason to question the consonance of these prohibitions with the broader principles of the LOAC. However, Judge Advocates have also long been taught that expanding or “hollow point” bullets were unlawful for use in combat. Several years ago, this prohibition piqued my interest. It is common knowledge that most US domestic law enforcement agencies use hollow point ammunition because of its effectiveness, so why couldn’t Soldiers use them? Soldiers in combat suggested that existing ammunition (like the M855 5.56mm round) was often ineffective against the enemy, especially in urban environments where bullets tended to pass “through and through,” causing insufficient injury to put the enemy out of the fight, and escalating civilian deaths from ricochets and the increased number of bullets fired. My research led to an article in 2010 arguing that the history of the 1899 Hague Declaration Concerning Expanding Bullets demonstrated that, not only was the ban on expanding ammunition ill-conceived and misunderstood from its inception, but the ban did not reflect customary international law. Until last month, aside from several articles written by Mr. W. Hays Parks, the Defense Department had not taken an official position on their use in combat beyond counterterrorism operations. 

Section of the DOD manual, “Expanding Bullets,” states that “[t]he law of war does not prohibit the use of bullets that expand or flatten easily in the human body.” Hollow point bullets “are only prohibited if they are calculated to cause superfluous injury.” The manual goes on to provide three reasons why expanding bullets are lawful for use in armed conflict:

(1) The 1899 Declaration on Expanding Bullets “only creates obligations for Parties to the Declaration in international armed conflicts in which all the parties to the conflict are also Parties to the Declaration” (the United States is not Party to the Declaration).

(2) The Defense Department determined in a 2013 review that the 1899 Declaration does not reflect customary international law.

(3) Expanding bullets as manufactured today are not “inherently inhumane or needlessly cruel.”

These rationales represent a significant shift in policy that Judge Advocates practicing international law need to understand.

First, the manual is absolutely correct in reciting the basic principles of international law that make the 1899 Declaration non-binding on the United States. The United States wisely did not sign the Declaration, in large part because the restriction presented to the 1899 Peace Conference was the result of both a sensationalized German study on expanding bullets and the political and military motivations of Britain’s European rivals. Simply put, the American representative, Captain William Crozier, recognized that the ban was nonsense and proposed language that instead would have prohibited bullets that “inflict unnecessarily cruel wounds.” The United States has consistently maintained this position since 1899, and despite the International Committee of the Red Cross’s (ICRC) assertion in their 2007 Customary International Humanitarian Law study that the restriction is customary international law (CIL), the Defense and State Departments correctly determined in 2013 that the Declaration is not CIL. While the details of the inaccuracies of the ICRC IHL study as applied to expanding ammunition are beyond this discussion, there is little doubt that DOD found that neither the usus nor opinio juris surrounding expanding ammunition support its prohibition for use in armed conflict as CIL.

Second, the manual asserts that the expanding bullets are not per se illegal unless they are calculated to cause superfluous injury. While the Rome Statute of the International Criminal Court (ICC) lists as a war crime “[e]mploying bullets which expand or flatten easily in the human body, such as bullets with a hard envelope which does not entirely cover the core or is pierced with incisions,” the Elements of Crimes to Article 8 of the Rome Statute requires that a perpetrator be “aware that the nature of the bullets was such that their employment would uselessly aggravate suffering or the wounding effect.” Ultimately, the DOD manual finds the “crime only applies to expanding bullets that are also calculated to cause superfluous injury and does not create or reflect a prohibition against expanding bullets as such.” In my judgment, this finding is correct, but the section on expanding bullets does not explain why expanding bullets are not calculated to cause superfluous injury, a critical oversight. In keeping with the often non-linear reasoning of the manual, one has to scroll down to section 6.6.2, “Superfluous Injury Rule—the Principle of Humanity,” to better understand why expanding ammunition is lawful for use in armed conflict.

The superfluous injury rule as recited by the DOD Law of War Manual “prohibits weapons that are designed to increase the injury or suffering of the persons attacked beyond that justified by military necessity.” Thus, the legality of expanding ammunition depends on whether or not their use is justified by the principle of military necessity. That is, the argument is not that expanding ammunition does not cause superfluous injury (although in my view, it does not), but rather that military necessity sometimes dictates the use of expanding ammunition in armed conflict. The Law of War Manual states that military necessity “justifies the use of all measures needed to defeat the enemy as quickly and efficiently as possible.” A plethora of research shows that expanding ammunition can, under some circumstances, be more efficient in incapacitating the enemy. More importantly, the principle of distinction, requiring “parties to a conflict to discriminate in conducting attacks against the enemy,” substantiates the lawfulness and utility of expanding ammunition in armed conflict.

Experience over the last decade in Iraq and Afghanistan, especially in urban environments, has shown that jacketed rounds can cause significant collateral damage to innocent civilian bystanders, either through ricochets or rounds that pass through the targeted body or even structures. As Professor Geoff Corn mentioned in an earlier post, Article 57 of Additional Protocol I to the Geneva Conventions of 1949 requires parties to a conflict to take precautions in the attack. Article 57(1) requires “constant care” to “spare the civilian population, civilians and civilian objects,” and Article 57(2) mandates “all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects.” When employing small arms ammunition in urban environments where civilians are present in large number, expanding ammunition can assist the United States in better complying with this fundamental rule.

Hopefully, future editions of the DOD Law of War Manual will better the argument for the lawfulness of expanding ammunition in armed conflict through emphasis on military necessity, but there is no doubt that the manual’s treatment of expanding ammunition represents a major shift in US policy. This shift seemed to have gone relatively unnoticed until the Army’s announcement last month that it can and will consider adopting expanding ammunition as it develops the next generation Modular Handgun System, the XM-17. That announcement has caught the attention of many in the blogosphere, and represents an important victory for the lawful use of an important weapon technology, albeit one that has been around for over a century. It has taken a long time, but it appears the efforts of many, from Captain Crozier to Mr. W. Hays Parks, have finally succeeded by providing Soldiers the ability to rely on a more efficient projectile for incapacitating the enemy in certain situations, while at the same time reducing avoidable civilian deaths and better complying with the spirit of the laws of armed conflict.

The views expressed above are those of the author and do not reflect the official policy or position of the US Army, Department of Defense or the US Government.