Denials of petitions for rehearing en banc are usually dull affairs, but not so the 113-page denial the D.C. Circuit issued two days ago in Al-Bihani v. Obama. The original panel opinion rejected Al-Bihani’s habeas petition on the ground that his acknowledged participation in a Taliban-affiliated paramilitary group justified his military detention pursuant to the September 2001 congressional Authorization to Use Military Force (AUMF). Along the way, Judge Brown, joined by Judge Kavanaugh, ruled in a brief analysis that the international laws of war were irrelevant to the interpretation of the scope of detention authorized by the AUMF. This was a surprising result, because lower courts assumed, the Obama administration argued, and many believed the Hamdi plurality ruled, that the laws of war were relevant to the interpretation of the AUMF. Al-Bihani sought rehearing en banc on this issue, but the seven D.C. Circuit judges not on the panel voted to deny, reasoning that “the panel’s discussion of [the role of international law-of-war principles in interpreting the AUMF] is not necessary to the disposition of the merits.”
One would have thought that would be the end of the matter. But surprisingly, the panel judges – Brown, Kavanaugh, and Williams – filed lengthy opinions that relitigated in much greater detail the relevance of international law to interpreting the AUMF. There is much to say about these rich opinions, and I hope to say more over the next few days. For now, I want to comment, unfortunately at length, on Judge Kavanaugh’s scholarly disquisition against what he calls (p. 29) the “radical argument” that the laws of war are relevant to the interpretation of the outer limits of what the AUMF authorizes the President to do. Since Curt Bradley and I made just such an argument, and since Judge Kavanaugh cites and relies on our work a great deal but expressly disagrees with us on this point (in footnote 23), I should perhaps explain why I continue to believe Bradley and I are right.
The central issue is what Congress meant when it authorized the President to use “all necessary and appropriate force” against the nations, organizations, and persons responsible for 9/11. The Hamdi plurality ruled that one thing it meant was that the President could detain enemy combatants until the end of the relevant conflict. The AUMF’s silence on detention was no bar to this conclusion, the plurality reasoned, because the AUMF must be interpreted in light of the laws of war. “[W]e understand Congress’ grant of authority for the use of “necessary and appropriate force” to include the authority to detain for the duration of the relevant conflict, and our understanding is based on longstanding law-of-war principles,” the plurality said. Using the laws of war in this way – as a canon to interpret congressional intent in a war authorization – has a long historical pedigree. As Bradley and I showed (pp. 2091-92), courts and executive branch officials used this reasoning in the Quasi-War with France and the Mexican-American War; and more broadly courts and executives had asserted in other wartime contexts that in the absence of congressional restrictions, presidents were entitled to do what the laws of war permit.
So it is not radical to use the international laws of war to inform what Congress in a broad and unqualified war authorization meant to empower the President to do. As Bradley and I explained (on 2091): “Because the authorization contemplates warfare, it is reasonable to assume that, absent other indicia of statutory meaning, Congress intended to authorize the President to take at least those actions permitted by the laws of war. Otherwise, the Commander-in-Chief would be placed at a unilateral disadvantage vis-à-vis the enemy and might be unable to prosecute the war effectively.” Judge Kavanaugh seems to agree (on 69): “As a practical matter, it would be quite odd to think that Congress, when passing the AUMF, did not intend to authorize at least what the international laws of war permit, subject of course to separate prohibitions found in domestic U.S. law. In that sense, international law can be said to inform judicial interpretation of the AUMF.”
The next issue – the contested issue – is whether the laws of war also inform the limits of what Congress authorized the President to do. Here a distinction is important. The issue is not, as some readers might take Judge Kavanaugh to be saying, whether the laws of war should be read in to the AUMF to prohibit the President from doing something. As Bradley and I explained (on 2096 ff.), the laws of war cannot inform the AUMF in that manner. Rather, the issue is the outer boundary of what Congress affirmatively authorized the President to do. The distinction is crucial because if the laws of war come in via the AUMF to bar the president from acting, we are in Jackson Category 3 territory and the president’s power to act is at its lowest ebb. But if Congress has simply not authorized the President to do something, then we are in Jackson Category 2 territory and the President retains significant power to act under his own constitutional authorities. As Judge Kavanaugh explains (on p. 78), even if the AUMF does not authorize the President to detain someone, he “possesses independent authority under Article II of the Constitution to act against al Qaeda and the Taliban – and to detain members of those groups – even without congressional authorization.”
So do the laws of war inform the limits of what Congress authorized the President to do in the AUMF? I believe so, for two reasons.
First, as Bradley and I argued (at 2094): “Since the international laws of war can inform the powers that Congress has implicitly granted to the President in the AUMF, they logically can inform the boundaries of such powers.” If the laws of war tell us what Congress affirmatively authorized when it authorized “all necessary and appropriate force,” they also tell us the outer limit of what Congress authorized.
Second, I think the Hamdi plurality embraced this view. In response to petitioner’s contention that the AUMF did not authorize indefinite or perpetual detention, the plurality said: “we agree that indefinite detention for the purpose of interrogation is not authorized.” Then, in the next sentence, the plurality added the language quoted earlier: “Further, we understand Congress’ grant of authority for the use of ‘necessary and appropriate force’ to include the authority to detain for the duration of the relevant conflict, and our understanding is based on longstanding law-of-war principles.” The reasoning here is plain: The AUMF authorizes the President to detain, but does not authorize the President to detain for purposes of interrogation or after the relevant conflict has ended. Where do these limits on what the AUMF authorized the President to do come from? “Longstanding law of war principles.”
The duration-of-conflict example is a particularly good one, because it shows the limitations of Judge Kavanaugh’s alternative sources for informing and limiting the AUMF. He thinks that any limits on the AUMF must come from domestic law alone without consideration of international law unless it has been expressly incorporated into domestic law (as, for example, in the War Crimes Act). But once the AUMF has authorized detention of an enemy combatant, there is no relevant domestic law I am aware of that would prohibit the President from detaining an enemy combatant after hostilities have ceased. (Hamdi held that the 18 U.S.C. § 4001(a) was no such bar.) A natural way to reach the obvious conclusion that the President lacks authority to detain enemy combatants after hostilities cease is that the AUMF authorized detention during but not after hostilities, and that this limit on what it authorizes derives, as Hamdi says, from the laws of war. (Judge Kavanaugh maintains, alternatively, that a “congressional authorization for the use of force obviously pertains to the war for which force is authorized and applies until Congress or the Commander in Chief ends the war.” But the AUMF authorizes the use of force against certain entities without time limitation, and it is designed “to prevent any future acts of international terrorism against the United States”; it is thus unclear why Judge Kavanaugh thinks the AUMF would not authorize the President to detain a dangerous al Qaeda terrorist after hostilities cease.)
I do not believe that using the laws of war to inform the boundaries of what Congress authorized the President to do has any radical or unattractive implications for international law’s status in the domestic legal system. It does not imply that customary international law comes into the domestic legal system as federal common law. Using the laws of war to inform the meaning of the AUMF is (as Judge Williams suggests on page 2 of his statement) akin to using a dictionary to inform the meaning of a statute; it is an extraneous source that, based on plausible assumptions, indicates congressional intent. One can use a dictionary in this way without thinking it part of domestic federal law; the same goes for the using laws of war in interpreting the AUMF. Nor does using the laws of war in this way commit one to thinking that the Charming Betsy canon applies to the AUMF. For reasons suggested in my article with Bradley (page 2098), I agree with Judge Kavanaugh’s conclusion (58 ff.) that it does not.
Nor does using the laws of war to inform the scope of the AUMF in any way commit one to thinking, as Judge Kavanaugh worries (footnote 23), that “international law trumps the President in resolving statutory ambiguities.” First, the President argues in this case for using international law to interpret the AUMF. Using international law as I suggest would in no way trumps the President here. Second, and more fundamentally, courts using international law to construe statutes should, especially in the war powers area, defer to the President’s interpretation of international law – especially customary international law, which is unusually vague and contested. Judge Kavanaugh seems to think (p. 65) that using the laws of war to inform the meaning of the AUMF commits a judge to giving more weight to an International Court of Justice ruling than to the President. I agree that the law-of-war issues implicated in Al-Bihani are particularly uncertain and contested, and that there is a danger of judges relying on proliferating extra-U.S. sources to identify the content of the laws of war. But I do not think these sources can properly trump the President’s view of the matter when courts use international law to interpret a war-related statute.
Those who know my writings know that few have more concern than I for the creeping growth of modern customary international law, or for the creeping judge-driven domestication of customary international law into domestic federal law. I thus share the general concerns that inform Judge Kavanaugh’s opinion, and I agree with most of his impressive and clarifying analysis of the relationship between international and U.S. domestic law (about which I will have more to say in later posts). But the central question raised by the Al-Bihani rehearing petition does not, in my view, implicate these concerns.