The phenomenon of employing proxy forces in contemporary conflicts has become one of the major legal and jurisprudential challenges at both national and international levels. Adopting a descriptive–analytical approach, this study re-examines the foundations of legitimacy and the scope of responsibility arising from the actions of proxy forces from the perspectives of Imami jurisprudence, Iran’s domestic criminal law, and international criminal law. It seeks to clarify the extent of convergence or divergence among these three legal systems in addressing this phenomenon. The findings indicate that Imami jurisprudence recognizes the legitimacy of using proxy forces only in situations of genuine threat and for the defense of the Islamic community, while holding the directing authority responsible and liable for resulting harm under principles such as la darar (no harm), causation, and shared liability. In Iranian criminal law, the doctrines of causation and the distinction between direct perpetration and indirect causation allow for the attribution of responsibility to states supporting proxy forces, and the rules governing multiple causes prevent the exclusion of liability. In international criminal law, individual criminal responsibility, command responsibility, and the rules on attribution of conduct of non-state actors to states render both proxy forces and their sponsoring states accountable. Overall, while all three systems acknowledge the conditional legitimacy of employing proxy forces, none absolves the responsible actors from liability arising from their actions.