This piece originally appeared on Lawfare.
The oral arguments in Monday's D.C. Circuit en banc review of Ali Hamza al Bahlul's military commission conspiracy conviction essentially came down to competing views of history. The government concedes that conspiracy is not a recognized war crime under international law. But rather than accepting chief prosecutor Brigadier General Mark Martins' plan to move forward using more credible charges, the Justice Department argued that the Guantánamo commissions can try conspiracy based on historical U.S. practices. Relying largely on research by prosecution team member Haridimos Thravalos (discussed on Lawfare here and here), the government asserts the existence of a "domestic" U.S. law of war which includes conspiracy to overcome concerns that its initial codification in the Military Commissions Acts of 2006 cannot be applied retroactively. Al Bahlul naturally disagrees.
After reviewing each authority cited by Thravalos' article and the government's briefs, I believe that al Bahlul has the best of this argument for reasons I expressed to the court in an amicus brief and have more fully developed in a draft law review article available here. As I see it, there are two basic flaws in the domestic law arguments:
(1) Virtually every credible reference to the law of war, including the sources the government relies on, describes the law of war as being part of international law.
(2) None of the cases cited as domestic "law of war" conspiracy prosecutions really stand up to exacting scrutiny. On closer examination, each one seems to (a) represent the prosecution of completed, rather than inchoate, conduct; (b) ground the conspiracy charges in domestic legal jurisdiction under martial law or military government rather than the law of war per se; or, (c) use conspiracy as a mode of liability rather than charging conspiracy as a substantive offense.