U.S. Defense Secretary Jim Mattis meets with Saudi Arabia’s King Salman Bin Abdulaziz Al-Saud in Riyadh, Saudi Arabia, April 19, 2017. (DOD photo by U.S. Air Force Tech. Sgt. Brigitte N. Brantley)

This article is the latest article in our forum on the Yemen crisis and the law.

If the United States is aiding and assisting the Saudi-led coalition in its violation of international humanitarian law, as a previous article in this series concluded is likely, then the United States is not only in violation of its responsibilities under State Responsibility doctrine, but also its well-accepted obligation not to aid and assist violations under Common Article 1 of the Geneva Conventions.

Common Article 1 obligates states to “undertake to respect and to ensure respect” for the Geneva Conventions in all circumstances. In March 2016, the International Committee of the Red Cross (ICRC) issued new Commentaries on the Geneva Convention—the first in more than six decades. As discussed in an article in the Texas Law Review, “Ensuring Responsibility: Common Article 1 and State Responsibility for Non-State Actors,” the ICRC Commentaries conclude that Common Article 1 imposes not only a negative obligation on states not to encourage violations of the law of armed conflict, but also (and more controversially) a positive third-party obligation on states to closely coordinate their activities with other parties, whether state or non-state actors. The Commentaries state: “Under the negative obligation, High Contracting Parties may neither encourage, nor aid or assist in violations of the Conventions by Parties to a conflict. Under the positive obligation, they must do everything reasonably in their power to prevent and bring such violations to an end.” Continued U.S. support for the Saudi-led military campaign in Yemen arguably violates both these negative and positive duties.

Beginning with the negative obligation: In Nicaragua, the International Court of Justice (ICJ) explained that Common Article 1 imposed on the United States “an obligation not to encourage persons or groups engaged in the conflict in Nicaragua to act in violation of the provisions of Article 3 common to the four 1949 Geneva Conventions” (para. 220). The ICJ found that the United States knew of allegations that the contras were violating international humanitarian law (IHL) and held that knowledge of these allegations was sufficient to show the foreseeability of future IHL violations by the non-state actor. As the United States knew that IHL violations were “likely or foreseeable,” it had an obligation to halt the provision of any support that could broadly be construed as encouragement. Because it had not done so, it had violated its obligations under Common Article 1.

In the current case of Yemen, the United States may similarly be in violation of the negative obligation under Common Article 1. The United States has provided support in the form of munitions, intelligence, and mid-air refueling, despite knowing of credible allegations that Saudi Arabia has violated IHL. The U.S. government reportedly restarted sales of weapons to the coalition only after receiving assurances that Saudi Arabia would take greater precautions to avoid indiscriminate targeting and adhere to IHL. However, states that make a good faith effort to encourage parties to abide by IHL can still be held to violate their Common Article 1 negative duties. In Nicaragua, the ICJ found the United States liable for violating Common Article 1 despite the existence of a CIA manual that the United States claimed was intended to discourage the contras from violating IHL (though the manual also included additional recommendations that encouraged violations) (paras. 255-56). Indeed, the ICJ took the manual’s recommendations aimed at “mitigating” the violations by the contras as evidence that the United States knew future violations were “likely or foreseeable.” Hence, it appears that violations of the negative obligation not to encourage or induce violations of the Geneva Conventions might not be mitigated by recommendations or assurances.

That is particularly true in cases where, as here, there is evidence that efforts to mitigate IHL violations may have been ineffective. Indeed, the Saudi-led coalition’s commission of IHL violations after it assured the United States it would take steps to mitigate them—as well as warnings that Saudi Arabia was incapable of adhering to IHL due to serious, systemic problems within its military—indicate that the recent IHL violations may well have been “likely or foreseeable” under the Nicaragua standard. Accordingly, continued U.S. support could be construed as encouragement in violation of Common Article 1’s negative obligations.

The United States may also be in violation of any positive duties that exist under Common Article 1, though these are less widely accepted. As already noted, the new ICRC Commentaries expressly embrace a positive obligation under Common Article 1 to take action to “ensure respect” of the Geneva Conventions. The ICRC was not the first to suggest that Common Article 1 imposes positive obligations. In its 2004 Wall Advisory Opinion, the ICJ adopted a more expansive reading of Common Article 1 than it had in Nicaragua. It found that the Article imposed negative duties “not to encourage” abuses, and also some positive third-state obligations. The ICJ interpreted Common Article 1 to imply that “every state party to [the Fourth Geneva] Convention, whether or not it is a party to a specific conflict, is under an obligation to ensure that the requirements of the instruments in question are complied with” (para. 158).

According to the ICRC’s legal staff, this positive obligation requires states “to exercise due diligence in choosing appropriate measures to induce belligerents to comply with the law.” States must take “all possible steps, as well as any lawful means at their disposal” to ensure respect for the Geneva Conventions. There is no bright-line rule for determining third-state obligations. Rather, the Commentaries stipulate a sliding scale whereby “the duty to ensure respect for the Geneva Conventions is particularly strong in the case of a partner in a joint operation, even more so as this case is closely related to the negative duty neither to encourage nor to aid or assist in violations of the Conventions” (para. 167). The ICRC legal staff has also drawn from the Bosnian Genocide case’s interpretation of due diligence and concluded that the scope of third-state positive obligations under Common Article 1 is context-dependent— it may depend on the precise diplomatic, geographic, social, and economic ties between the third state and the belligerent.

Whether the United States has violated its positive obligation under Common Article 1 may again turn on the adequacy of U.S. mitigation measures. Pursuant to the ICRC’s due diligence standard, states may discharge their affirmative obligations under Common Article 1 by undertaking efforts to mitigate and prevent violations. That IHL violations by the Saudi-led coalition have continued does not necessarily mean that the United States has not discharged its positive obligation. The due diligence obligation does not require states to attain specific outcomes. Rather, the obligation has been interpreted as only requiring states to “make every effort” to prevent the violation. Whether the assurances that the United States has received mitigate its positive obligation under Common Article 1 turns on the credibility of the assurances. If Saudi Arabia’s assurances cannot be considered credible—or if the Saudi military was incapable of adhering to IHL regardless of the assurances—then the United States was obligated not to provide any form of support. By this reasoning, the United States would be obliged to cease its support for the Saudi-led coalition and it may also be required to adopt additional affirmative measures, such as diplomatic pressure and public denunciations, in order to avoid further liability.