What is The Common Law of War?  

by Jens David Ohlin

Since the recent al Bahlul en banc decision before the D.C. Circuit, I have been thinking a lot about the Common Law of War. As others have already analyzed in detail (Steve, Peter, JonathanMarty & Steve), the D.C. Circuit upheld Bahlul’s conviction for conspiracy but threw out his conviction for material support for terrorism and solicitation. Material support and solicitation are unavailable for pre-2006 conduct because they are neither international crimes nor historically charged before military commissions. Conspiracy, on the other hand, is a different story. While it seems pretty clear that conspiracy is not a stand-alone offense under international law, the government has relied on the argument that conspiracy is historically chargeable before a military commission as part of the “common law of war.”

The exact status of the common law of war theory remains unknown because the court’s majority applied “plain error” review and not de novo review on the merits. Some judges concluded that Bahlul waived his objections by not raising them at trial (when Bahlul was declining legal assistance). For his part, Judge Kavanaugh appeared sympathetic to the common law of war argument, which arguably departs from his previous notes of skepticism regarding the theory in Hamdan II.

Since the common law of war idea is still wide open, I’ve been trying to come to terms with it and articulate precisely why I’ve been uncomfortable with it in the past. Indeed, when I first heard the government’s assertion of this theory, I was deeply skeptical and found it almost outrageous. The law of war is international by definition—it is the same for everyone and that’s the whole point of it. The law of war is based on reciprocity and it makes no sense to think of it as a creature of domestic law.

That being said, I think the issue is more complicated than I initially assumed.  In particular, it is important to note that Lieber himself makes reference to the common law of war in article 13 of the Lieber Code. Also, Richard Baxter, in his famous article on spies and unprivileged belligerency, concludes that acts of belligerency by an unprivileged belligerent simply aren’t violations of international law at all – they are violations of domestic criminal law. That’s absolutely correct. The absence of the privilege means that the unprivileged belligerent cannot exempt himself from the demands of domestic law. That’s something far different from an international crime. Unfortunately, Baxter also says in the preceding sentence that the saboteurs in Ex Parte Quirin were “no doubt” triable under the statutes and “military common law of the captors” – though he never explains what he means by this. Presumably he felt that the saboteurs in Quirin were subject to military commission jurisdiction despite the fact that their crimes were domestic violations, though he never articulates his reasoning. Of course, I don’t want to parse Baxter’s article like it’s gospel; I find there’s too much of that already with people treating semi-authoritative Commentaries like treaties. But I still find it interesting that both Baxter and Lieber used the phrase or something close to it.

So why is it so difficult to understand the common law of war? Here are four possible reasons:

1. We no longer live a common law world. Well not exactly. The U.S. is still part of the common law, in the historical sense, but really the common law doesn’t play the role it once did. It has substantially evolved. Statutes and regulations play a much larger role now – and this applies in almost every field of law. This certainly applies in the criminal law, where even the idea of a common law crime sounds just bizarre to today’s students. It’s just so far removed from how the law operates today.

2. Although state courts in the U.S. continue to evolve the common law in each jurisdiction in subject areas that are not covered by a particular statute (say tort law), this endeavor is temporally removed from its historical roots in common law England. Although the law in each jurisdiction can all be traced back to a common source, the doctrines have been developed in unique and different ways in each court. The common law – as something truly common across jurisdictions – has receded into history.

3. The law of war in general, and the jurisdiction of military commissions in particular, were woefully under-theorized in previous generations. This was certainly true in the Civil War, when other than Ex Parte Milligan as an enduring constraint on military jurisdiction, there was insufficient attention paid to developing a deep theory of military jurisdiction. Famously, Ex Parte Quirin was a rush decision, arguably fast-tracked because the Supreme Court was concerned that the administration might execute the prisoners before a decision was reached – which would have dealt a near-fatal blow to the Supreme Court’s institutional legitimacy and its self-asserted purview, announced in Madison v. Marbury, to say what the law is. It is no surprise that we now look back on Quirin as “not this Court’s finest hour” (Hamdi v. Rumsfeld, Scalia J. dissenting). One way of putting the point is to follow Steve Vladeck and say that the Court has never fully rationalized why military commissions are exempt from the Article III requirement of trial before a regular court. Another way of putting the point is that during the Civil War the concept of military jurisdiction was under-theorized and we are only now playing catch-up.

4. There is something that unites our use of the terms “international law” today with how the term “common law” might have been used in previous generations. This might help explain why there is an international law of war today and a common law of war in the past.  Although they are different, what unites them is a shared participation in a larger legal culture. For international law, the larger legal culture is the international order, with its unique sources for lawmaking (treaties, custom, etc.) and international organizations. For the common law, the larger legal culture is the law that is “common” to many jurisdictions who are all participating in a common legal culture and apply its law together – the “common law.” Although the common law is not the same as international law, it is something larger than pure domestic law, and as such it could, in theory, and historically as well, fulfill some of the demands of reciprocity that the laws of war demand. The problem, of course, is that the common law doesn’t function that way in today’s world. The whole point of the law of war is that it has to be bigger than just domestic law. And maybe the common law in the past was just big enough to support the law of war in some limited sense. Whether that’s enough in today’s world, I really don’t know.


14 Responses

  1. International law was, until recently, a “common law” in the sense that it was not written down but was, nevertheless, understood by all nations and interpreted and applied by courts. Although there are small specific elements of the “laws of war” that are now covered by treaties, modern nations have been much more interested in dealing with humanitarian law and have mostly not formalized in treaty the rules about men killing one another.

    So while the Geneva Conventions cover the treatment of prisoners once they have fallen into the hands of the enemy, the mechanics of surrender, the white flag, offer and acceptance of terms, and so on remain mostly unwritten but universally understood. One feature of surrender is that the enemy soldier who surrenders agrees implicitly to follow the lawful orders of superior officers in the army to which he is surrendering. If he subsequently refuses a direct order, he can be tried just like a US soldier who committed the same offense, but you probably won’t find statutory text for this.

    Thus in Quirin, the court noted that military courts had jurisdiction over military common law offenses: “It is no objection that Congress in providing for the trial of such offenses has not itself undertaken to codify that branch of international law or to mark its precise boundaries, or to enumerate or define by statute all the acts which that law condemns. … Congress had the choice of crystallizing in permanent form and in minute detail every offense against the law of war, or of adopting the system of common law applied by military tribunals so far as it should be recognized and deemed applicable by the courts. It chose the latter course.”

    Given that unwritten law must be interpreted by the courts, and that the unwritten laws of war must be interpreted by military courts (because, for example, no Article III court can try the offense of “insubordination” or “refusal to follow the orders of a superior officer” because they do not exist in civilian criminal statutes), then the question of authority arises if US military courts interpret an element of the common law differently from German military courts. One would expect that the US courts would tend to honor prior US practice, creating a “US common law of war” with regard to the detailed interpretation of otherwise universally accepted general principles.

    I would like to complicate your thinking about Richard Baxter by quoting in full a footnote from the Quirin decision:
    “[ Footnote 9 ] On September 29, 1780, Major John Andre, Adjutant-General to the British Army, was tried by a ‘Board of General Officers’ appointed by General Washington, on a charge that he had come within the lines for an interview with General Benedict Arnold and had been captured while in disguise and travelling under an assumed name. The Board found that the facts charged were true, and that when captured Major Andre had in his possession papers containing intelligence, for the enemy, and reported their conclusion that ‘Major Andre … ought to be considered as a Spy from the enemy, and that agreeably to the law and usage of nations … he ought to suffer death.’ Major Andre was hanged on October 2, 1780. Proceedings of a Board of General Officers Respecting Major John Andre, Sept. 29, 1780, printed at Philadelphia in 1780.”

    The Supreme Court references this as a precedent, but the interesting question here is what was the source of authority for General George Washington to make the charges and try the case in the first place. Clearly the Continental Congress did not bother to formalize the laws of war in domestic statue. There could not have been a US common law of war before there was a United States. The cited justification was not to Congress or the US, but that this was “agreeably to the law and usage of nations”. Put another way, the precedent for the trial and execution of Andre was that four years earlier the British had executed Captain Nathan Hale for the exact same crime, thus demonstrating that such a prosecution was agreeable to the law and usage of nations.

    However, the offense was not a violation of international law or a “war crime”. Nobody expected the British to arrest, try, or execute Andre any more than they expected the US to arrest, try, and execute Hale. Each country authorized its officers to act as spies, and what they did was only illegal to the enemy, although the offense was defined in the international common law, it was not an offense against the international law, but rather a common law military offense against the enemy to which it was directed.

    Nor was this a crime in Article III courts, because while “espionage” is a crime, “crossing lines without uniform” is a military offense only defined in the common law of war and only chargeable in military courts.

  2. Jens,

    I am no student of US domestic law, but for those of us who do not find the concept of common law crimes bizarre, I see some appeal in your first suggestion — that the common law of the US recognised certain types of activities committed in the context of war as criminal. And presumably further, that the common law of the US recognised the jurisdiction of military commissions to try those common law offences.

  3. Jens,
    As far as I can see this is not that dissimilar to the practice of States that incorporate international crimes within their domestic law but expand their ambit beyond that recognised under international law. Genocide and its protected groups comes to mind.
    In this instance, it is simply the case that the United States has (supposedly) a historical practice of undertaking exactly such action with respect to war crimes by punishing individuals for conspiracy when international law has not done so – hence a US “common law” of war. One could even frame it within a persistent objector prism. I do not per se see a problem with it unless one accords with the view that States can only ever prosecute international crimes as they are defined at international law or not prosecute them at all (as international crimes). I’m not sure that many people would agree with the latter proposition – there is scope for deviation (how far domestic international crimes can deviate from the definitions under international law is another (much trickier) question).
    Thus the real question in my view is whether the US Military Commissions were in fact granted jurisdiction only over international crimes as defined under international law or not (and thus potentially covering the US common law of war). Hamdan II had apparently answered that question, but it has now been overruled by Al Bahlul. So who knows.
    Something I don’t quite get though is why bother charging conspiracy (and inviting all the problems and headaches) when you have to option to charge a totally completed offence (commission)? I understand that you have to prove less on a conspiracy charge, but would it really be that much difficult to prove that the 9-11 attacks and others actually happened (rather than simply an agreement as to their future commission)? Maybe I’m missing something..?

  4. Howard, very interesting discussion.

    The first quote from Quirin that you reproduce makes it sound like the common law of war is a part of international law.

  5. Ian, good comment. I suppose the issue is that the principle of legality has evolved substantially in the interim. While unwritten common law crimes were once considered the norm, it is generally assumed today that the principle of nullem crimen sine lege scripta requires deeper legislative involvement in penal definition.

    There is an interesting hypothetical here. Suppose a state were to completely repeal its penal statute and tell its courts to return to punishing offenders based on common law crimes. Would that be permissible? I think it would violate a fundamental principle of criminal law, though I guess it wouldn’t be unconstitutional per se.

  6. Note that Ex Parte Quirin says, “From the very beginning of its history this Court has recognized and applied the law of war as including that part of the law of nations which prescribes, for the conduct of war, the status, rights and duties of enemy nations as well as of enemy individuals.” 1 U.S. 27-28. In that sentence, the word “including” is important, and suggests the Court viewed the “law of war” as broader than merely the international law. If the “law of war” was co-extensive with the international law, there would have been no reason to use the word “including,” as the Court could simply have said it had recognized and appliced the law as that part of the law of nations . . .

  7. Oops, meant 317 U.S. 1, 27-28 for the citation.

  8. Response…There could not have been a US common law of war before there was a United States. The cited justification was not to Congress or the US, but that this was “agreeably to the law and usage of nations”

    The United Nations War Crimes Commission addressed the various examples of state practice among the Allies, including “United States Law And Practice Concerning Trials Of War Criminals By Military Commissions, Military Government Courts And Military Tribunals” in an annex to volume 3 of its “Law Reports of Trials of War Criminals”. It observed that:
    The United States Military Commissions are an old institution which existed prior to the Constitution of the United States of America. They have been described as the American Common Law War Courts. They were not created by statute, but recognised by statute law. … & etc.

    Response… The first quote from Quirin that you reproduce makes it sound like the common law of war is a part of international law.

    To an extent it was considered as such, since The United Nations War Crimes Commission included the practice of US and other Allied Commissions and Tribunals in that area in its international law reports. For example, the Chinese Law of 24th October, 1946, was covered in an annex to volume 14. It contained an elaborate list of offenses regarded as constituting war crimes, similar to the one which was drawn up by the 1919 “Commission on the Responsibility of the Authors of the War and on Enforcement of Penalties.” It contained many of the Hague and Geneva rules, but explicitly expanded the list to include rape; kidnapping of children; kidnapping females and forcing them to become prostitutes; enforcing collective torture; use of poison gas or bacteriological warfare; use of inhuman weapons; torturing of non-combatants; mass deportation of non-combatants; internment of non-combatants and inflicting on them inhuman treatment; usurpation of the sovereignty of the occupied territory; scheming to enslave the inhabitants of occupied country or to deprive them of their status and rights as nationals of the occupied country; and depreciating the value of currency or issuing unlawful currency notes; & etc.

    Some of those either had or subsequently have been progressively codified, but the Chinese understood them to be pre-existing common law of war offenses.

  9. Jens, now I’m from Australia, so some might call into doubt how well we deal with English let alone Latin, but I note the word ‘scripta’. My guess is a common law court would agree that no crime/penalty without a pre-existing law, but that pre-existing law might be common law and need not be legislative. This might be even more the case in a jurisdiction that does not have a constitutional, bill of rights or plain old legislative rule on the issue but is relying on a common law principle/maxim to decide on the issue you raise.

    Just before I shock our continental European friends too much and they vow never to come to Australia, I might add that the class of common law crimes in the remaining common law jurisdictions in Australia is probably now closed — in other words, new crimes can now only be created by legislation.

  10. Drawing several of these comments together, it seems to me that we are debating between at least two conceptions. (1) The common law of war is part of the international law of war. Or the opposite: (2) The international law of war is one part of the common law of war, the latter being bigger and extending beyond the confines of internationally defined offenses.

    Also, on the legality point, the Supreme Court required legislative involvement, leading to the post-Hamdan MCA in 2006. Depending on which view above is correct, one can either view the MCA as an interpretation of the international law of war, or one can view it is a codification of the common law of war, which is broader and includes offenses not included in the international law of war.

  11. The international laws of war consist of treaties and unwritten but universally accepted principles taught to military officers over centuries during a period when multinational treaties did not generally exist. These unwritten rules are called the “common law of war” today to distinguish them from the (mostly 20th Century) written treaties.

    Military commissions are authorized (down through the centuries) to try a variety of offenses. There are “war crimes” so serious that all nations are obligated to try anyone who commits the offense. There are strictly military matters like “insubordination” which deal with military discipline but do not rise to the level of actual crimes. There are special offenses like crossing lines without uniform that are serious (capital offenses) but with peculiar limitations (once a spy returns to his own lines he is free and cannot subsequently be tried for his prior spying, a rule that would never be included for a real crime). There are also entirely normal crimes (murder, theft, rape) committed by civilians in an area of military combat or occupation.

    The Quirin quote shows that Congress could have simply assigned to Military Commissions jurisdiction over all offenses traditionally tried by commissions, and that language would be OK. The MCA, however, enumerated specific offenses without being particularly clear what the enumeration was intended to do. Clearly it was not a “codification of the common law of war” because it leaves a lot of things out. The question was, did this limit the jurisdiction of the Commissions just to the listed offenses, or was the result(as the al Bahlul decision seems to suggest) to grant jurisdiction over offenses that were not traditionally within its jurisdiction? I have no idea what Congress intended. One of the judges ruled that since “murder in violation of the laws of war” could only mean killing of a civilian by a soldier, and since a soldier would be a lawful combatant excluded by the MCA from the jurisdiction of the commission, that nobody could be tried for that particular enumerated offense. After a matter of speaking he was spot on, but that is not, I believe, the way the language is currently being interpreted. So do not use the MCA to clarify anything.

  12. Howard, your description of it makes it sound like customary international law. How is it different?

  13. there were earlier uses of the phrase, but it seems to relate to confusion between U.S. domestic law and customary international law, a confusion that has existed especially for judges who are unfamiliar or insufficiently familiar with the nature of customary internaitonal law as well as its direct incorporation as part of the law of the U.S. and not as mere “common law.” My treaties, International Law as Law of the United States, chpt. 1, documents partly why CIL has not simplistically ever been mere “common law.”

  14. Edward: that is not a proper interpretation of the word including. The phrase is “as including” and there was more than the customary laws of war at the time, there were also treaty-based laws of war. The famous paragraph in Ex parte Quirin is important for the Supreme Court’s recognition that it had and can apply the customary laws of war directly (direct incorporation without a federal statute), since the first statute incorporating all of the customary laws of war as offenses against the laws of the United States and for purposes of judicial decisionmaking concerning the status, right, and duties of individuals, etc., at least (as including), was the 1916 Act (the language of which now appears in 10 USC sections 818 and 821).

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