Thanks to Kevin for his very thoughtful response. I share Kevin’s wariness about making mere membership a war crime. However, both the Nuremberg cases like Steinbrinck and subsequent authorities are consistent with a more cabined war crime that entails active membership coupled with a substantial nexus to unlawful violence. Viewed in this cabined way, a membership prohibition does not violate the principle of legality.
As Jonathan A. Bush has argued in his definitive study, The Prehistory of Corporations and Conspiracy in International Criminal Law: What Nuremberg Really Said, 109 Colum. L. Rev. 1094 (2009), the Nuremberg tribunals used membership offenses to convict individuals like Steinbrinck who played leading roles in organizations, id. at 1148, and avoided imposing sanctions on “average complicitous Germans.” Id. at 1161. Given Nuremberg’s salience in the constellation of the law of armed conflict and international criminal law, it is reasonable to view Steinbrinck as providing the notice to al-Bahlul and his ilk required by the principle of legality. Similarly, one would treat an American business executive as receiving notice of a U.S. Supreme Court case that interpreted the criminal provisions of the antitrust laws. The Supreme Court has the power to tailor the antitrust offense to constitutional requirements; indeed, using the avoidance canon, the Court has repeatedly read provisions of the U.S. Code in light of constitutional principles. Steinbrinck uses an analogous approach, keyed to principles of the law of armed conflict.
Notably, Kevin hasn’t indicated any disagreement with Steinbrinck, which convicted a principal funder of the SS who provided indispensable financial support despite knowing the barbaric nature of the SS’s activities. Kevin also does not dispute that the law of armed conflict can criminalize al-Bahlul’s design of Martyr Wills that managed the public relations benefits that Al Qaeda realized from the September 11 attacks and the purported pathway to salvation of the attackers themselves. Kevin asserts only that subsequent developments have made the offense of membership obsolete. However, as applied to defendants like Steinbrinck or al-Bahlul, Kevin reads those developments far too broadly.
Kevin’s discussion of the International Law Commission (ILC) illustrates the problems with his broad reading of subsequent developments. As Kevin aptly notes, the ILC’s 1996 commentary rejected “criminal responsibility based on the membership of an individual in…a criminal organization.” Id. at 47 n. 130. A war crime hinging on mere membership would clearly constitute the “collective criminal responsibility” that the ILC rejected. However, a membership offense keyed to active membership coupled with a substantial nexus to unlawful violence, a la Steinbrinck or al-Bahlul, hinges on the actions of the individual, and thus does not constitute an impermissible attribution of collective guilt. The ILC commentary does not rule out such an offense. Indeed, the ILC did not claim to present an exhaustive list of offenses that reflected individual responsibility. It expressly noted that “the inclusion ofcertain crimes in the Code does not affect the status of other crimes under international law”, id. at 17, and further acknowledged that “there might be other crimes of the same character that were not presently covered by the Code.” Id. at 19.
Kevin is right that membership offenses need to be handled with care. The CMCR’s record to date is uneven at best, with Hamdan as an inauspicious initial foray. However, nothing in international law, including the principle of legality, bars the CMCR from defining membership offenses to include the conduct of an Al Qaeda official such as al-Bahlul, who played a significant organizational role in the 9/11 attacks.