Human Rights Watch joins partners in this brief arguing that the charge of material support for terrorism is not a violation of the laws of war and therefore such a charge falls outside the limited jurisdiction of military commissions. The brief further argues that the charge of material support for terrorism is not only in excess of Congress’ duty to define and punish, but is dangerously overbroad, as it would transform any participation of a non-state actor in an armed conflict into a crime under international law. There is no legitimate basis for such a consequence in any recognized source of international law or in the jurisprudence relevant thereto.