In a recent post, HHJ Blackett has commented on the lawfulness of the joint Israeli and American use of force against Iran.
The essay advances a doctrinal and normative claim about the lawfulness of the use of force against Iran. Doctrinally, the argument is that the United States and Israel could lawfully resort to force on two distinct bases: first, self-defense under Article 51 of the U.N. Charter beginning on February 28, 2026; and second, Security Council authorization following the adoption of Resolution 2817 on March 11, 2026. Normatively, it contends that the Charter should not be interpreted through an unduly narrow, historically fixed reading that fails to account for contemporary threats such as proxy warfare, transnational terrorism, and nuclear proliferation.
The essay frames the Article 51 argument around three asserted predicates. For Israel, it points to Iranian support for armed attacks by Hamas, Hezbollah, and the Houthis. For the United States, he relies on Iran-sponsored attacks against Americans and U.S. facilities. For both states, it adds Iran’s alleged continued pursuit of nuclear weapons, coupled with openly hostile rhetoric toward the United States and Israel. On this view, Iran’s conduct satisfies the threshold for self-defense not merely through direct state action, but also through substantial involvement in proxy violence and through the scale of the danger posed by a developing nuclear capability.
The essay then places considerable weight on Resolution 2817, which we should read as a resolution condemning Iranian attacks on neighboring Gulf states, threats to close the Strait of Hormuz, and affirming the inherent right of individual and collective self-defense. The essay further suggests that the absence of Security Council condemnation of prior U.S. and Israeli actions implies retrospective validation and furnishes a legal basis for continued or broader multinational action. That is a notably expansive reading of the resolution’s legal effect, and it is central to the claim that force was lawful both before and after March 11.
The major theme is an institutional critique. The argument goes that the Charter’s collective-security design has not functioned as intended because the veto has often impeded rather than enabled peace enforcement. There is emphasis on the failure of the Military Staff Committee and the collapse of the Charter’s expectation that member states would maintain forces available for rapid U.N. action. These structural failures help explain why states have increasingly relied on self-defense rationales rather than awaiting Security Council consensus. We, therefore, are presented with contemporary law on the use of force as a product not only of treaty text, but also of state practice developing in response to institutional paralysis.
The legal analysis of self-defense relies heavily on the evolution of “armed attack” and “imminence.” The International Court of Justice’s reasoning in Nicaragua supports the proposition that a state may commit an armed attack through proxies, irregulars, or substantial involvement with non-state actors. Also, post-9/11 practice argues that terrorist attacks can trigger Article 51. From there, the essay endorses an expanded conception of anticipatory self-defense, drawing on the Caroline formula but arguing that imminence should now be assessed not only temporally, but also by reference to the gravity of the threatened harm, the adversary’s capabilities, and the nature of the potential attack.
At the same time, the essay expressly limits the scope of its intervention. While the legality of resort to force is addressed, how hostilities are conducted is not; for example, even a lawful initial use of force does not immunize a state from later violations of the law of armed conflict. In sum, the essay offers a modernization thesis: Article 51 must evolve through state practice to remain operationally relevant in an era defined by proxy violence, terrorism, and existential strategic threats.
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