Doctrine of legitimate defense
International Law | Natural Law
The following article reorients mainstream conceptions of self-defense by defending a broader doctrine of legitimate defense that, in limited circumstances, justifies unilateral intervention. The source of the doctrine is natural law, which was explicitly incorporated into the text of UN Charter article 51. The effect of this incorporation was to preserve, as a carve-out from the prohibition against force in Article 2, the natural law rights of defensive force. Specifically, the Article concludes that defensive force under natural law included, in extreme situations, a right of intervention in rogue States that refused to comply with natural law. The Article then provides a normative foundation for the doctrine of legitimate defense by showing how the right of self-determination, the right to be free from genocide, and the right to self-defense, all flow from a more primary right to exist that applies to nations and peoples. Finally, drawing on earlier work published with George Fletcher, the Article explains how a national group’s right of self-defense can trigger a third party’s right to intervene on its behalf. This reading of Article 51 shows how its explicit incorporation of natural law and its textual reference to “legitimate defense” provides the conceptual ground for a modern doctrine of humanitarian intervention. However, unlike other legal justifications for humanitarian intervention that are framed as “exceptions” to article 51, the doctrine of legitimate defense is based on a textual interpretation of that provision.
Jens David Ohlin, "The Doctrine of Legitimate Defense," 91 International Law Studies (2015)