In his remarks to the American Society of International Law earlier this month, State Department Legal Adviser Brian Egan stated that the United States’ commitment to upholding the law of armed conflict extends “to promoting law of armed conflict compliance by our partners.” He observed that partnerships with both state and non-state actors are important to current US military operations, including recent campaigns against ISIL. In what appears to be a very carefully modulated statement, he then explained:

Some have argued that the obligation in Common Article 1 of the Geneva Conventions to “ensure respect” for the Conventions legally requires us to undertake such steps and more vis-à-vis not only our partners, but all States and non-State actors engaged in armed conflict. Although we do not share this expansive interpretation of Common Article 1, as a matter of policy, we always seek to promote adherence to the law of armed conflict generally and encourage other States to do the same. As a matter of international law, we would look to the law of State responsibility and our partners’ compliance with the law of armed conflict in assessing the lawfulness of our assistance to, and joint operations with, those military partners.

In doing so, he took the important step of signaling the US government’s willingness to consider an interpretation of Common Article 1 of the Geneva Conventions that entails positive obligations to ensure respect of the law of armed conflict by partner states and non-state actors.

Common Article 1 states that “The High Contracting Parties undertake to respect and to ensure respect for the present Convention in all circumstances.” The International Committee of the Red Cross (ICRC) recently provoked renewed attention to Common Article 1 with its Commentaries of 2016. The new commentaries were no small undertaking. They offer the most comprehensive interpretation of the Geneva Conventions the ICRC has provided since the highly influential original 1952 Commentaries by Jean Pictet. In the new commentary on Common Article 1, the ICRC explains that duties “to respect” are distinguishable from duties “to ensure respect.” The former applies directly to states and their organs, and require that they not directly violate the laws of armed conflict. The duty “to ensure respect,” however, creates independent obligations on states to ensure other states and non-state actors do not violate their own duties under international law.

Under the ICRC’s interpretation, the duty to ensure respect entails both “negative” and “positive” obligations. Negative obligations include restrictions on aiding and abetting other states or non-state actors in violations of the Geneva Conventions. For example, in its 1986 Nicaragua decision, the International Court of Justice (ICJ) characterized the US’s Common Article 1 obligations towards the contras it funded and trained to overthrow the Nicaraguan government as a duty “not to encourage” violations of the law of armed conflict. Additionally, Article 16 of the Draft Articles on State Responsibility provides a standard for liability when a state aids or abets another state in commission of an internationally wrongful act. Arguably, however, as some commentators suggest, Common Article 1 places more exacting investigative duties on states to avoid aiding international law violations than do the Draft Articles.

The real controversy, however, concerns the scope of states’ positive obligations under Common Article 1. The ICJ acknowledged the existence of such positive Common Article 1 obligations — at least as they pertain to states’ obligations toward other states — in its Wall Advisory Opinion. Unfortunately, the ICJ offered little guidance as to the precise scope of such obligations or the standard of liability associated with their breach.

The ICRC has been careful to reject some of the most expansive possible interpretations of the positive obligation under Common Article 1 in its new commentaries. For example, it expressly denies that Common Article 1 offers a “humanitarian intervention” exemption to the UN Charter’s Article 2(4) prohibition on the use of force. Instead, the ICRC argues that states’ positive obligations to ensure respect for the Conventions ought to be framed as “due diligence” requirements. This means states are obligated take reasonable measures — short of the use of force — to ensure the Conventions are not violated by other parties to the armed conflict. The obligations do not carry strict liability; instead, they only require states to take adequate steps towards their discharge. Comparable due diligence obligations exist in the context of international human rights law and have been applied by both the European Court of Human Rights and the Inter-American Court of Human Rights.

The ICRC is clear that when a State takes affirmative steps toward partnering with non-state actors (e.g., funding, training, equipping, or sharing intelligence), its positive Common Article 1 obligations toward the non-state actor will be more extensive than when they do not. The new commentaries are less clear, however, about whether due diligence obligations extend to any and all parties to an armed conflict. Significant ambiguity remains as to how far, and exactly to whom, positive Common Article 1 obligations extend. Some worry that the commentaries imply that the US might even have legally enforceable positive obligations to those state and non-state parties with whom it has no connections. For example, that it could be used to impose duties on the United States to ensure that Russian separatists in Eastern Ukraine do not violate Common Article 3 of the Geneva Conventions even though the United States has never provided them any measure of support.

Egan clearly foreclosed US acceptance of such a broad interpretation of the scope of due diligence obligations under Common Article 1 (the “expansive interpretation” to which he referred). But what has gone largely unnoticed is his signal that the US government might accept a more modest, but still extremely important, step forward. He explains that “as a matter of international law,” the US will look to the law of state responsibility “and our partners’ compliance with the law of armed conflict in assessing the lawfulness of our assistance to, and joint operations, with those military partners.” This statement signals that the US government will not partner with those who do not comply with the law of armed conflict, and that it will do so not only as a matter of policy but “as a matter of international law.”

Buried near the end of a long and substantive speech, this statement has been largely overlooked. But it is an extremely important step forward. In a forthcoming article we, together with our coauthors, argue that the current law of state responsibility is inadequate to holding states responsible for their non-state partners’ violations of international law. We suggest that Common Article 1 obligations could provide an important supplement to the current state responsibility regime. Egan has signaled the US government’s willingness to consider positive obligations under Common Article 1 for partner state and non-state actors. The United States could — and we hope it will — lead the way in forging a middle ground between the broadest interpretation of Common Article 1 and states’ sometimes reflexive resistance to what they perceive as additional legal obligations.