Five brief thoughts on yesterday’s Hamdan decision:
First, I am less confident than Steve and Ben that this opinion forecloses conspiracy claims in military commissions. The historical arguments for a conspiracy charge in military commissions under the laws of war, while not slam dunks, are (as Steve and Ben acknowledge) more powerful than similar arguments for material support. Yesterday’s opinion states that “there is a strong argument that aiding and abetting a recognized international-law war crime such as terrorism is itself an international-law war crime,” and adds that “there are other similar war crimes,” a phrase that could mean many things. And Justice Kennedy, whose vote will be crucial in the Supreme Court, declined to join Justice Stevens’ plurality conspiracy analysis in Hamdan, and noted in that context that “Congress, not the Court, is the branch in the better position to undertake the “sensitive task of establishing a principle not inconsistent with the national interest or international justice.” I am not (yet) maintaining that conspiracy will survive yesterday’s decision. But I think the strong suggestions of its death are premature, especially if the issue reaches the Supreme Court. (I also think, relatedly, that it would be imprudent to seek certiorari re yesterday’s decision, which will almost certainly would be affirmed; the conspiracy charge has a better chance in the Court, I think, if considered on its own in the first instance, rather than after, or even in combination with, material support.)
Second, even if conspiracy falls, commissions still have available secondary liability tools like aiding and abetting, and, possibly, joint criminal enterprise. These are harder to prove than material support. But it is not the case that military commissions would be bereft of secondary liability tools if conspiracy falls. For this reason I think Ben is too quick to conclude that if conspiracy falls, only the 9/11 and Cole perpetrators will be triable by military commission.
Third, along one dimension yesterday’s court of appeals decision strengthens the legitimacy of military commissions by demonstrating that any military commission decision will be subject to vigorous judicial review.
Fourth, and on the other hand, if conspiracy falls, and if (for example) al-Bahlul's conviction is reversed, I think there is a good chance the government will continue to detain al-Bahlul in military detention, an incapacitation option reaffirmed in yesterday’s opinion. While I think (for reasons sketched here) that military detention following military commission acquittal is constitutional, such a course would undoubtedly look bad, and would make military commission trials – and, for that matter, civilian criminal trials, where, as Judge Kaplan suggested in Ghailani, an acquittal can also be followed by detention – less legitimate in the eyes of many.
Fifth, yesterday’s decision noted correctly that “[i]t is often difficult to determine what constitutes customary international law, who defines customary international law, and how firmly established a norm has to be to qualify as a customary international law norm.” But then for the proposition that “the imprecision of customary international law calls for significant caution by U.S. courts before permitting civil or criminal liability premised on violation of such a vague prohibition,” and for a similar proposition at the crucial point in the material support analysis (block-quoted by Steve in the first point in his post), the court cited Sosa, a case premised on federal courts’ limited federal common law powers when crafting customary international law civil causes of action based on a 1789 statute. One might have thought that Quirin was more on point than Sosa, and that its more fluid and deferential approach (to the President and Congress) to a similar issue in a similar context would provide sounder guidance.