The Decline in Declarations of War: An Exchange

Why have states stopped declaring war in their conflicts with each other? I was among the first to tackle this question in a 2012 article published in Security Studies and a subsequent book. I argue that the decline in use of declarations of war was driven by the increase in number and change in character of international humanitarian law (IHL)—the laws of war governing the use of force. When scholars address new questions, there is a firstmover advantage, but I fully recognize that being first does not necessarily mean being correct. Thus, I very much appreciate Katherine Irajpanah and Kenneth A. Schultz’s thoughtful engagement with my work. In the nearly ten years since the publication of my article, my thinking about international law and norms has evolved, although not in a way that would lead me to recant my original argument. To begin, I note that Irajpanah and Schultz (hereafter “IS”) and I agree that declarations of war are more than curious bygones. War declarations served important purposes in signaling in international conflict, and their decline can be informative as to the nature of interstate war today. We also agree that declarations of war have important implications for domestic politics and that, more generally, they help bound war in time; that war has fuzzy borders at both its start and end today is not cause for celebration. IS take issue with my “provocative” claim that the proliferation of IHL is related to the decline in declarations of war. They focus on an alternative explanation that I find less persuasive: in effect, that the United Nations (UN) system has created a substitute for declarations of war—self-defense claims. A key part of their argument speaks to what they view as one of