Responsibility for the Crime of Aggression under International Law

This book makes a simple but consequential claim: individuals who decisively influence a state’s decision to use armed force should be held criminally responsible for aggressive war.

Challenging the prevailing orthodoxy, it reconstructs the leadership clause in the definition of the crime of aggression and offers a new attribution framework that reflects how decisions about war are actually made. Under this approach, liability is not confined to heads of state and top military leaders but extends to civilian power brokers, private actors, and third-state officials who, as reason-giving and reason-demanding participants in key moments of deliberation, exercise decisive influence over whether a state goes to war – or continues one. By clarifying who counts as a “leader” and why, the book charts a principled middle path between overcriminalising ordinary participation in war and immunising those who set unlawful wars in motion. Grounded in Nuremberg and Tokyo jurisprudence and contemporary doctrine, it offers a timely rethinking of individual responsibility for the unlawful use of force.