[Update: Tony Arend (G'town) has a persuasive take in response to the questions raised below. See here.]
Hamdan’s conviction this morning on material support charges has led many people to ask whether (i) material support was a war crime between 1996 and 2001 and (ii) if not, whether this violates the Constitutional prohibition on ex post facto prosecution. Judge Allred ruled on these issues on July 14, in this opinion . He held as follows:
a. The Ex Post Facto Clause does apply to Hamdan
b. There is evidence for and against the proposition that material support is a war crime
c. Because the Constitution grants Congress the power to “define” and punish violations of the law of nations, courts must defer to Congress insofar as it concludes that material support was a war crime at the time of Hamdan’s conduct.
In short, the ex post facto issue turns on a separation of powers question concerning the allocation of interpretive authority (something not usually in issue): does the “define and punish” clause require courts to give binding deference to a legislative conclusion that material support not only should be but always has been a war crime. Only after rejecting that proposition would a reviewing court then reach an independent judgment on the merits of the interpretive question. This will, no doubt, be a central issue on appeal.