Just Security editors occasionally select a noteworthy law review article, essay, or book on topics that may be relevant to our readers—especially if it intersects with national security practice on the ground. The current issue of International Law Studies includes an important article on the legal risks for states and officials in partnering with foreign military forces. The author, Brian Finucane, is an attorney-adviser for Political-Military Affairs at the U.S. Department of State, but the article is naturally written solely in his personal capacity. Although this article was part of a conference at the Naval War College on the topic of Syria, it is unmistakable that the legal problems it tackles cut across other conflicts in which the United States and other countries either establish partnerships or provide assistance to foreign military forces. We highly recommend it for anyone thinking about these complex issues. In this post, we highlight some of the most important parts of Brian’s analysis.

 I. The Legality of Actions of Partner/Recipient Forces

A significant legal question raised when a state partners with or assists another military force (e.g., the United States working with Iraqi forces to clear Mosul) is whether the partner is likely to engage in internationally unlawful conduct. The bulk of Brian’s article focuses on legal frameworks that apply to the actions of the assisting state. However, he first addresses the legality of recipient or partner forces’ conduct. Two parts of this analysis deserve emphasis.

First, Brian explains that the proper standard for the commission of a “war crime” includes deliberate actions as well as recklessness. Brian writes, “Not only may ineptitude result in violations of [the law of armed conflict], but in some circumstances a mistaken targeting decision due to an attacker’s incompetence may implicate individual criminal responsibility.” He collects a good array of sources in support of these conclusions (see note 5). (Notably Brian’s analysis of the mental state required to commit a war crime is fully consistent with Just Security posts by Ryan, by Beth Van Schaack, and by Alex Whiting).

Second, Brian explains that the lower standard of negligence applies to violations of the law of armed conflict that do not amount to a war crime. This is also consistent with the Just Security posts and perhaps worth highlighting most of all for policymakers who lack a legal background. The important point is that even if a military force’s actions do not amount to international crimes due to a lack of the requisite mental state, those actions may nevertheless amount to breaches of the law of armed conflict if committed through negligence.

II. International Legal Responsibility for the Actions of Foreign Partners

Brian observes that states may have international legal responsibility for the actions of their state or non-state partners—a topic of growing importance for the United States.  The United States is increasingly reluctant to go it alone in military interventions. The U.S. has frequently partnered with other states (for example, over 60 states are involved in the U.S.-led counter-ISIL operation in Iraq).  It has also partnered with non-state actor groups, including Syrian opposition groups—which the U.S. has treated as its ground component in counter-ISIL operations in Syria.  But what happens when these groups violate the law of armed conflict? Brian examines four possible sources of legal liability.

First, he considers the law of state responsibility, which may apply whenever a State exercises sufficient control over a non-state partner’s actions.  As Brian rightly notes, there are two broad legal standards for state responsibility: “effective control,” and “overall control.” But, given the stringent conditions applied to both tests, Brian writes, “with respect to many of the partner relationships in the Syrian conflict and partnered operations more generally, neither the effective nor overall control standards appear likely to be directly implicated.” (One of us has reached a similar conclusion—see this article by Oona.)

Second, Brian focuses on a provision of state responsibility that applies, according to the text of the ILC’s 2001 Draft Articles of State Responsibility, only to the provision of aid and assistance to state partners.  (One would have to mount a separate analysis to determine whether this provision applies, as a customary international law matter, to aid and assistance to non-state partners.) In particular, article 16 of the ILC’s Draft Articles provides that “[a] State which aids or assists another State in the commission of an internationally wrongful act by the latter is internationally responsible for doing so if . . . that State does so with knowledge of the circumstances of the internationally wrongful act; and . . . the act would be internationally wrongful if committed by that State.”  Brian rightly—and importantly—notes that there is continuing ambiguity about the precise mens rea required to trigger Article 16 responsibility. In particular, he concludes that, “there may be risks associated with the provision of assistance to a State partner even if the assisting State did not desire the commission of any wrongful act.”  (For more on Article 16, see this post by Ryan and Miles Jackson, which is broadly consistent with Brian’s analysis.)

Third, Brian looks to the duty to ensure respect for the law of armed conflict—again a legal responsibility that applies to both states and non-state partners.  He reviews the new ICRC commentaries, which provide argue that Common Article 1 of the Geneva Conventions provide for an obligation on states to ensure respect for the conventions: “States, whether neutral, allied or enemy, must do everything reasonably in their power to ensure respect for the Conventions by others that are Party to a conflict.” States, in other words, must make every lawful effort to ensure compliance with LOAC. Brian notes that the ICRC’s interpretation is “not shared by the United States.” (For a different view, see Oona’s post with Zachary Manfredi here; see also Ryan’s post concerning potential inconsistencies in the US position over time)  Brian goes on, however, to note that applying the ICRC’s interpretation in the context of the Syrian conflict would mean that, if an assisting state were aware of systemic abuse of law of war detainees by a partner, the assisting state would be required to take steps to remedy the situation.

Brian’s last observation is that “transfer of certain conventional arms by an assisting state to a partner would be inconsistent with the provisions of the Arms Trade Treaty (ATT) if the assisting State knew the arms would be used to commit violations of LOAC.” Again, Brian notes that there is a stringent mens rea requirement—the official responsible for authorizing the expert must “have direct or clear knowledge at the time of the authorization” that the recipient will use the arms to commit a specified crime in order for the prohibition to apply. States are also required to consider whether there are adequate mitigation efforts available—and, if there remains an “overriding risk” that the exported arms could be used to commit a serious violation of IHL, the State is obligated not to authorize the export. (For an early post on the ATT, see this analysis by Abby Zeith.)

Together these provide an important compendium of the possible sources of legal liability for states that partner with state or non-state actors in armed conflict.

III. Criminal Liability for War Crimes Committed by a Partner Force

Brian usefully explains the legal risks—under the international criminal law standard of aiding and abetting—that might arise for officials of an assisting state when partner forces commit war crimes. Importantly, Brian explains that the so-called mental element required for such liability, as indicated by  “the overwhelming majority of cases from international criminal tribunals . . . is some form of knowledge as opposed to a purpose standard.” (For agreement on this point, see Ryan’s post on aiding and abetting liability, and Beth Van Schaack’s post.) Finally, Brian notes some important examples that could satisfy the actus reus element of aiding and abetting liability. He provides as an example: “If officials of an assisting State provided intelligence, fuel, maintenance or munitions that had a ‘substantial effect’ on enabling a Syrian airstrike that constituted a war crime.”

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In the final summation, Brian’s article is an important contribution to contemporary discussions of some of the most vexing issues that are sure to arise time and again for the United States and other countries in modern armed conflicts. We commend Just Security’s Michael Schmitt, who is the editor of the International Law Studies, for another fine article in his series.