For the record, the Buchanan Amendment is a bad idea, and I hope that it dies in conference. In addition to being constitutionally vulnerable in at least some applications (Milligan anyone?), and hamhanded in its effort to deny discretion to the executive branch to decide which prosecution forum to use when choices are available, it seems to me that it reflects unsound assumptions about the actual operation of commissions. Haven't people figured out yet that the commission system is no longer substantially friendlier to prosecutors than the civilian system? Do supporters of this approach not realize that the jury is still out on whether various additional procedural and evidentiary rights--above all, the right to confront witnesses--attach in commission proceedings (a conclusion the Supreme Court is *much* more likely to reach, I suspect, should the Buchanan Amendment become law)? That the capacity of the commisions sytem to prosecute conspiracy and support offenses remains sharply contested (and, again, may be more likely to be resolved against the government if the Buchanan amendment becomes law)? None of that is to say that the commission system is a bad system; on the contrary, what I just said also suggests that it's defensible along many dimensions for which it is often cricitized. But this notion that it somehow on the merits is a better place to prosecute is at best highly debatable, and at worst flat out wrong. In the end, I can't help but think that the Buchanan Amendment amounts to triple-dog daring the Supreme Court to grant cert. in every commission-related case that later comes down the pipe, resulting in rulings aiming to bend the procedural and substantive law of that system towards civilian norms.
A final thought: I wonder how much of this mania for the commission option reflects an unjustified assumption that this is the only way to enable/compel the executive branch to (i) use military force to effectuate captures or (ii) interrogate captured terrorists without presentment to a judge or access to counsel for some substantial period. I strongly suspect that at least the latter is part of what drives some to support Buchanan-style limitations on prosecutorial discretion. But if so, it's all misguided. Nothing in law or policy requires the government to choose a soup-to-nuts option of either ordinary criminal-investigation-and-prosecution or military-interrogation-and-commission-prosecution. These pathways can be mixed-and-matched, as a general proposition.