The Illegality of 'Genuine' Unilateral Humanitarian Intervention

32 European Journal of International Law 613 (2021)

32 Pages Posted: 13 Dec 2019 Last revised: 13 Feb 2023

See all articles by Kevin Jon Heller

Kevin Jon Heller

University of Copenhagen (Centre for Military Studies)

Date Written: November 23, 2019


The activation of the crime of aggression at the ICC has renewed interest in one of the oldest and most fraught questions of the jus ad bellum: whether a state is entitled to unilaterally use force on the territory of another state for humanitarian purposes. Scholars who support unilateral humanitarian intervention (UHI) generally make two interrelated claims. The first is positivist: that unilateral intervention is lawful if it is genuinely intended to end mass atrocity. The second is normative: that genuinely humanitarian unilateral intervention should be lawful, because in the right circumstances it can serve as an effective mechanism for protecting civilians from harm.

In this article, I criticise both claims. I begin by arguing that, from a positivist perspective, even genuinely humanitarian unilateral intervention violates the prohibition of the use of force and qualifies as a criminal act of aggression. I then argue that the historical record undermines the normative attractiveness of UHI, because it is extremely difficult to find an actual example of a unilateral intervention motivated primarily by humanitarian concerns, especially one that improved the humanitarian situation in the territorial state. Finally, I conclude by arguing that the basic effect of insisting on the legality of UHI is to weaken one of the few clear prohibitions in international law for no discernible benefit, making the desire to decriminalize such intervention a well-meaning equivalent to the notorious ticking time-bomb scenario.

Keywords: jus ad bellum, use of force, UN Charter, self-defense, humanitarian intervention, non-intervention, invasion

Suggested Citation

Heller, Kevin Jon, The Illegality of 'Genuine' Unilateral Humanitarian Intervention (November 23, 2019). 32 European Journal of International Law 613 (2021), Available at SSRN: or

Kevin Jon Heller (Contact Author)

University of Copenhagen (Centre for Military Studies) ( email )


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