Steve, Ben, Jack, and Bobby have already posted some excellent thoughts on the DC Circuit's decision in Hamdan II. I agree with many of them. In particular, I think Jack is right to suggest that, wholly apart from its correctness as a legal matter, the decision might not be all that good for those Guantanamo detainees who would otherwise have been prosecuted in a military commission for material support (and no other charge), as such convictions have thus far yielded relatively short sentences after which the defendant has been released from U.S. custody. If material support is not an available charge for such detainees, the most likely alternative course (even for low-ranking individuals who don't pose any significant ongoing threat) may simply be their continued indefinite detention under the law of war, with release extremely unlikely any time soon. People will have different views about whether that is a good development, but I think Jack's probably right about it as a descriptive matter.
I want to offer some additional thoughts on Hamdan II, focusing on some specific aspects of the reasoning in Judge Kavanaugh's opinion. Before doing that, I suppose I should acknowledge that while serving in the White House in 2009, I was involved in the efforts that led to the reforms of the military commissions system in the Military Commissions Act of 2009. As Steve has pointed out, the Obama Administration's position during that process (expressed in public testimony by David Kris and Jeh Johnson) was that material support should be excluded from the list of crimes triable by military commission, precisely because we saw a significant risk that courts would conclude that material support is not a traditional violation of the law of war. Congress in its wisdom refused to go along with the Administration's recommendation on this point. And now here we are.
But my point here is not to say "we told you so." Instead, I want to shift gears and emphasize that the precise statutory interpretation issue upon which the DC Circuit's decision rests is really quite subtle and difficult -- more difficult, I think, than the commentary has thus far acknowledged. (Apologies in advance for the length of what follows.)
To start, it is worth emphasizing that Judge Kavanaugh's opinion does not conclude that it would violate the Ex Post Facto Clause to try someone in Hamdan's situation (a noncitizen held at Guantanamo at the time of his trial) for an offense that was not legally specified at the time of his actions. I am inclined to think that it would be unconstitutional to do so, on the ground that the Ex Post Facto Clause is best understood to constrain the government's actions even against noncitizens at Guantanamo. Others likely disagree. Judge Kavanaugh's opinion expressly reserves the issue. (See slip op. at 18-19 n.7.) Instead, the opinion concludes that Congress did not intend its codification of material support in the Military Commissions Act of 2006 to apply to conduct predating that statute.
Here are the key passages from the opinion (from slip op. at 16-18; ellipses mine):
Cngress was quite concerned about the ex post facto implications of retroactively prosecuting someone under the Act for conduct committed before its enactment. Congress tried to deal with any ex post facto problem by declaring in the text of the statute that “[t]he provisions of this subchapter codify offenses that have traditionally been triable by military commissions. This chapter does not establish new crimes that did not exist before its enactment, but rather codifies those crimes for trial by military commission.” . . . . The Act continued: “Because the provisions of this subchapter (including provisions that incorporate definitions in other provisions of law) are declarative of existing law, they do not preclude trial for crimes that occurred before the date of the enactment of this chapter.”
. . . .
As Congress itself recognized in the statutory text, retroactive prosecution by military commission could . . . raise serious constitutional issues, at the very least. As stated in the statutory text, however, Congress believed that the Act codified no new crimes and thus posed no ex post facto problem. As we explain below, Congress’s premise was incorrect. The statute does codify some new war crimes, including material support for terrorism. The question for ex post facto purposes is this: If Congress had known that the Act was codifying some new crimes, would Congress have wanted the new crimes to be enforced retroactively?
I agree: For purposes of interpreting whether the statute authorizes material support prosecutions based on conduct pre-dating the initial codification of material support in 2006, the question is whether Congress would have wanted such charges to be available if it had known that the 2006 Act's codification entailed the creation of a new crime. The DC Circuit answered no. That might be right, but I think it's a much more difficult question than Judge Kavanaugh's opinion suggests.
The key to Judge Kavanaugh's reasoning is found in a passage immediately following the material quoted above:
To begin with, the statutory text reveals a tight causal link between (i) Congress’s belief that the statute codified only crimes under pre-existing law and (ii) Congress’s statement that the statute could therefore apply to conduct before enactment. That causal link suggests that Congress would not have wanted new crimes to be applied retroactively. The Executive Branch agrees with that interpretation of the statute, stating: “Congress incorporated ex post facto principles into the terms of the MCA itself.” Brief for the United States at 66.
That might be one way to read the statute, but it's not the only way. The operative language listing material support as a triable defense contains no express nonretroactivity limit. It does not say, for example, that material support is a triable offense "only based on conduct post-dating this enactment." In fact, when the statute does speak to charges based on pre-enactment conduct, it expressly says the opposite (emphasis mine): "Because the provisions of this subchapter . . . are declarative of existing law, they do not preclude trial for crimes that occurred before the date of the enactment of this chapter." In that respect, it is clear that Congress expected that defendants would be tried for material support based on conduct pre-dating the 2006 Act.
Judge Kavanaugh's opinion stresses the first part of the passage I just quoted (emphasis mine again): "Because the provisions of this subchapter . . . are declarative of existing law, . . . ." On his reading, Congress made material support available for pre-2006 conduct only because it believed material support was a traditional law of war violation. Perhaps. But it's also possible that Congress was saying something rather different -- that it intended material support (and every other offense enumerated in the 2006 Act) to be chargeable for pre-2006 conduct, and that it simply thought there was no possible ex post facto problem with doing so because material support (and every other offense it enumerated) was a traditional violation of the law of war. On that reading, the DC Circuit could be right that material support is not a traditional law of war offense (I think it't entirely right on that point), but that would not mean Congress did not intend to make it an available charge for pre-2006 conduct. Instead, it would simply mean that Congress was wrong to say that such charges would raise no ex post facto issues. But that error need not affect the operative language of the statute, which seems straightforwardly to contemplate material support charges based on pre-2006 conduct.
To see all of this more simply, return to what Judge Kavanaugh identifies as the key question: "If Congress had known that the Act was codifying some new crimes, would Congress have wanted the new crimes to be enforced retroactively?" Let's put that same basic question slightly differently: "If Congress in 2006 had known that the only way to bring material support charges in a military commission against individuals then at Guantanamo was to enforce a new crime of material support retroactivity, would it have authorized such a charge?" Seems to me the answer is probably yes.
Of course, to read the statute that way would be to run headlong into the ex post facto issue. As I noted above, I am inclined to think it would violate the Ex Post Facto Clause to prosecute a Guantanamo detainee for material support based on pre-2006 conduct. At the very least, I think doing so would raise a serious constitutional question. The Hamdan II panel apparently saw it that way too, which is why Judge Kavanaugh's opinion invoked the canon of constitutional avoidance to justify its interpretation of the Act. That is, because allowing retroactive material support charges would raise a "serious question of unconstitutionality," and because the court saw "something of an ambiguity" in whether the statute in fact authorizes such charges, it read the statute not to authorize them. Slip op. at 18. But here I would note two final things.
First, it is not entirely clear to me that this was an appropriate use of the avoidance canon. As the Supreme Court has repeatedly explained, the canon only applies when the meaning of a statute is ambiguous. Here I'm not sure if that's the case. Instead of being ambiguous, the statute seems simply to contain some internal tension. On one hand, it expressly authorizes material support charges based on pre-2006 conduct. There doesn't seem to be any textual ambiguity in that. But on the other hand, the statute expresses the view (in language that arguably isn't legally operative, but instead just describes Congress's "thinking") that the statute creates no retroactivity/ex post facto issues. The DC Circuit was right, in my view, to say that Congress was wrong on the latter point. But I'm not sure that's enough to create an ambiguity in the express authorization of material support charges. (I wonder if Judge Kavanaugh himself saw this as a bit of a stretch of the avoidance canon, when he said that there was "something of an ambiguity" in the statute, which is not how a court would ordinarily put things.) In other words, I'm not convinced that it was legitimate for the DC Circuit to use the avoidance canon to duck the ex post facto issue. I think the better approach may have been to face up to it.
Second, even assuming the statute is ambiguous, the avoidance canon only applies if an interpretation making material support available would raise serious constitutional concerns -- not just any conceivable constitutional issue, but serious constitutional concerns. Here, upholding the material support charge against Hamdan would in fact have raised two constitutional issues. First, setting retroactivity aside, does Congress have the authority to authorize military commissions to hear charges that are not traditional offenses against the law of war (which material support is not, as the DC Circuit's opinion shows)? That's the constitutional issue for purposes of the availability of material support for conduct post-dating the 2006 Act, but it's an issue in a case like Hamdan's too. The panel in Hamdan II explicitly avoided answering that issue on the ground that it was unnecessary to resolve the case before it, but Judge Kavanaugh (in a footnote speaking only for himself) said that, issues of retroactivity aside, he thinks Congress does have the authority to make material support triable by military commission. Apparently, he thought that was a sufficiently easy call that the avoidance canon did not even apply.
For Judge Kavanaugh, then, the only serious constitutional issue in the case was the ex post facto issue. And whatever they thought about the congressional power issue noted above, the other members of the panel evidently agreed that the ex post facto issue was a serious one. What's striking about the opinion is how little Judge Kavanaugh says about precisely why it's a serious constitutional issue. The idea that retroactive criminal legislation presents serious ex post facto concerns is clear enough. Here, though, the real question is whether the Ex Post Facto Clause applies at all, since we're talking about the prosecution of a noncitizen in a military commission at Guantanamo Bay. Under the Supreme Court's decision in Boumediene, we know that noncitizens at Guantanamo have the constitutional privilege of habeas corpus. Yet under existing DC Circuit caselaw it is not clear that they have any other constitutional rights. In fact, a number of DC Circuit decisions have suggested quite aggressively that the Suspension Clause is the only part of the Constitution that applies to noncitizens at Guantanamo. The most aggressive of those decisions have been justly criticized for failing to come fully to grips with the analysis in Boumediene itself.
On that point, Hamdan II may signal a possible shift in direction, or at least moderation in stance. Judges Kavanaugh, Ginsburg, and Sentelle all apparently agree that there is at least a serious possibility that Guantanamo detainees have rights under the Ex Post Facto Clause. The opinion does not quite come out and say so, perhaps out of a desire not to provoke the ire of other members of the DC Circuit, like Judge Randolph. Analytically, I think the opinion would have been better if it had addressed the point more directly. But the implication seems clear.