Intervention by Invitation: Military Action with Consent

This panel explores the evolving legal landscape surrounding “military action with consent”—also known as “intervention by invitation” or “military assistance on request”—and the significant doctrinal, practical, and normative questions it raises in international law. Specifically, the panel will examine instances of cross-border military operations justified by the consent of the territorial State, which can blur the line between friendly engagement and aggressive force in international law.

Over the past decade, several military operations have relied—explicitly or implicitly—on this legal rationale. These include the French intervention in Mali (2012–2022), the U.S.-led coalition operations against ISIS in Iraq (2014–ongoing), the Saudi-led intervention in Yemen (2015–ongoing), and Russian and Iranian support for the Assad regime in Syria (2015–2024). In other cases, such as Russia’s intervention in Ukraine (2014–ongoing), the invocation of consent has been viewed as manifestly invalid. Despite the ubiquity of this legal argument in state practice and its acceptance in case law (e.g., Nicaragua (1986), DRC v. Uganda (2005)), significant ambiguity remains concerning its doctrinal foundations and limitations.

The panel will engage with key questions: Who can issue valid consent on behalf of a State? What formal or substantive requirements govern the issuance, scope, and withdrawal of such consent? How should international law address the potential for abuse in cases where the legality of consent is contested? In addition, the panel will consider how this doctrine interacts with other international legal regimes, including self-determination, human rights law, and international humanitarian law—especially in scenarios involving internal armed conflict or contested sovereignty.

Speakers and Topics:

• Dr Hannah Woolaver (University of Cape Town) will assess the ‘purpose-based approach’ to the legality of military action with consent.
• Professor Brad Roth (Wayne State University) will speak on the negative equality doctrine and the putative emergent democratic norm in the validity of State consent to military action with consent.
• Professor Mary-Ellen O’Connell (University of Notre Dame) will address the requirements of proportionality and necessity in the legality of military action with consent.

The panel will draw on work done in the International Law Association Committee on the Use of Force: Military Action with Consent. All panel contributors are members of the Committee, of which Dr Woolaver is Co-Chair.