Quick Thoughts on UBL’s Killing — and a Response to Lewis

by Kevin Jon Heller

A number of students and colleagues have asked me if I believe that Usama bin Laden’s killing was legal. I’m swamped with teaching and writing responsibilities, so my ability to blog is limited.  But I thought I’d at least put my thoughts on record, skeletal though they may be.  And I want to reply to what I think are two misleading statements in Michael Lewis’s post regarding the relationship between the jus ad bellum and the jus in bello.

First, with regard to the UBL question: I have no doubt that killing UBL was legal. To begin with, I think the applicable legal regime is international humanitarian law (IHL), not international human-rights law (IHRL) — a conclusion that can be reached in a number of different ways.  The best rationale is that UBL was a member of an organized armed group (“original” al Qaeda) taking part in the armed conflict in Afghanistan.  In the alternative, I think we can say (although it is a closer call) that the hostilities in Pakistan rise to the level of armed conflict and that UBL was a member of an organized armed group (original al Qaeda or al Qaeda Pakistan, if the two are distinct entities) taking part in that conflict. Either way, UBL was legitimately targetable with lethal force at any time, subject only to the principles of distinction and proportionality.  And nothing I’ve seen indicates that the attack on UBL’s compound violated either of those principles.

Importantly, I don’t think the result would be any different if the applicable regime was IHRL, not IHL.  As I’ve written before, IHRL limits targeted killing more than IHL, but it by no means prohibits it. And I think UBL’s killing was permissible, for reasons articulated by the inestimable Marko Milanovic:

IHRL does allow states to deliberately kill individuals if they have a sufficient justification. OBL was undoubtedly a highly dangerous individual, whose apprehension was needed to protect the lives of others. The US military operation at least contemplated the capture of OBL; the troops on the ground shot him in a firefight. There are no indications that he had tried to surrender before being shot. Under the same facts, his killing would have been equally as lawful had he been hiding somewhere in Alaska rather than in Abbottabad.

Now, to Lewis.  He and I obviously agree that UBL’s kiling was lawful and that the applicable legal regime is IHL, not IHRL.  It is important to recognize, however, that his explanation of why IHL applies rests on an unacceptable conflation of the jus ad bellum and the jus in bello.  He writes:

[S]tate practice strongly supports the view that an expansive reading of Article 51 to include non-state actors is appropriate. Sunday’s operation was another example of state practice undertaken with the belief that the boundaries of the battlefield are not determined by geopolitical lines but rather by the location of participants in an armed conflict, whether the participants are states or non-state actors. This continues to be the standard for determining where the law of armed conflict is properly applied.

The second and third sentences of this statement are correct, but they in no way follow from the first sentence.  IHL applies to the operation for one reason and one reason only: because hostilities rising to the level of armed conflict exist in Afghanistan and/or Pakistan (and UBL was a member of an organized group taking part in one of those conflicts). Whether the operation against UBL is consistent with Article 51 of the UN Charter (which I agree it was) has no bearing on that question; the consistency issue is exclusively one of the jus ad bellum — namely, whether the operation violated Pakistan’s sovereignty. Differently put, if the objective requirements of armed conflict do exist, IHL applies even if Article 51 did not authorize the operation; IHL does not distinguish between just and unjust, legal or illegal, uses of force.  (Which means that it is perfectly legal for a soldier fighting an illegal war to kill an enemy combatant.)  Conversely, if the objective requirements of armed conflict do not exist, IHL does not apply even if Article 51 did authorize the operation.  The jus ad bellum question is irrelevant to the jus in bello one.  (A conclusion reached, it’s worth noting, by the Farben, Krupp, and Ministries tribunals in the aftermath of WW II.)

I would also take issue with this statement in Lewis’s post:

The United States military sent some of its most highly trained combat experts into Pakistan without asking for Pakistan’s permission. They entered Pakistan’s airspace in military helicopters specifically equipped to defeat the Pakistani air defenses. According to a national security official in the immediate aftermath of the operation they went there for the sole purpose of killing Osama bin Laden, a goal which they quickly accomplished. These facts support characterizing this as a military operation conducted under the laws of armed conflict and not a law enforcement operation.

This is not necessarily wrong, but it is at least misleading.  Although how a state chooses to respond to a threat from a non-state actor is relevant to whether hostilities rise to the level of armed conflict, the form of the response — military or law-enforcement — does not determine whether an armed conflict exists.  It is simply one factor, the importance of which is debatable.  States do not get to unilaterally determine whether IHL applies to hostilities with a non-state actor; again, that is an objective question determined by the intensity of the hostilities and the organization of the parties to the conflict.  Nor, it is important to add, would we want states to be able to trigger IHL simply by calling in the military instead of deploying police officers.  If that was the test, the Syrian government would be able to argue that its recent decision to massacre protesters with tanks was governed by IHL, not by IHRL, because the use of tanks means that the massacre was “a military operation conducted under the laws of armed conflict and not a law enforcement operation.”

The bottom line: yes, killing bin Laden was legal.  But it was legal because the operation that killed him complied with IHL, not because it was permitted by Article 51. The latter issue is relevant only to whether Pakistan has the right to complain about the United States’ violation of its sovereignty.


47 Responses

  1. “There are no indications that he had tried to surrender before being shot,” writes Milanovic.

    But there is no evidence of anything; hence these kinds of “arguments” (or mere assertions based on nothing) are quite pointless.

  2. Why do you exclude issues of jus ad bellum from the determination of the legality of the US use of force against bin Laden? Surely whether or not the US was entitled to use force in Pakistan is part of the determination of the legality of the operation. Reducing this issue to one of whether Pakistan had a right to “complain” after the fact denies the legal nature of the sovereign right to territorial integrity, and the bindingness of the prohibition of the use of force, which can be circumvented with reliance on Art. 51. There are two sides to the legality of a military strike- jus ad bellum and jus in bello. Why do you deny that violation of the first body of law would not make the strike against bin Laden unlawful?

  3. HDW,

    There are two sides to the strike, and both the jus ad bellum and the jus in bello are relevant to the legality of the operation.  But only the JIB is relevant to the legality of killing bin Laden.  The two areas of law protect different interests: the JAB protects a state’s sovereignty; the JIB protects (among other things) combatants and civilians in armed conflict.  As I said the post, as long as IHL applies and the U.S. forces complied with the rules of IHL, the killing was not illegal.  And it was not illegal even if the use of armed force against Pakistan violated the JAB.

    Consider a hypothetical situation.  Assume that Obama invades Mexico tomorrow and seizes its oil.  During the invasion an American soldier shoots and kills a Mexican soldier guarding one of Mexico’s oil wells.  That killing is not murder, nor is it a war crime, because IHL applies to the conflict (IHL is automatically triggered whenever one state attacks another state) and IHL does not prohibit one combatant from killing another.  And that killing is not murder and not a war crime even though the U.S. attack clearly violated the jus ad bellum.  That does not mean that the JAB violation is irrelevant; Mexico is entitled to protest the violation of its sovereignty, and Obama (and other U.S. political and military leaders) may be guilty of the crime of aggression under customary international law.  But the illegality of the invasion does not affect the right of combatants in the resulting armed conflict to kill in ways permitted by IHL.

    Does that help?

  4. Thanks for the post and sharing your views.

    I won’t weigh in on the legality of the killing. However, I want to make a distinction that I think is important and one which is getting lost in the shuffle. There are two general strands of argument in this debate (and others in international law): 1) that the killing of bin Laden is legal and 2) that the killing of bin Laden is just and therefore moral.

    Many people will not see the distinction. As international politics is increasingly legalized, justice is increasingly equated with what is legal under international law. I think this may be a good time to remember what Judith Shklar taught us of the dangers of conflating the law with morality.

    I think this opens us up to a broader debate which considers not only whether killing bin Laden was legal and therefore just but whether it was legal yet unjust, illegal but just or both illegal and unjust.

  5. Please, please, please — at least initially, let the reader know what IHL, not IHRL means.  I want to follow what you are saying, but it’s not like those are such obvious acronyms.  Indeed, there are so obscure to the rest of the world that you can’t find them using google.  Argghh!!!

    thanks 🙂

  6. Anon,

    Sorry — done!

  7. Article 51 is about “armed attacks”, not about people sleeping in bed : “Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain inter- national peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.”

  8. One thing I’m not sure I quite understand, Kevin.  This sentence:  “Conversely, if the objective requirements of armed conflict do not exist, IHL does not apply even if Article 51 did authorize the operation.”

    There have, of course, been many examples over the years in which a nation has engaged in isolated acts of self-defense that have not risen to the level of, and have not resulted in, armed conflict.  Indeed, the Caroline doctrine itself, however one might want to characterize it, contemplates such self-defense actions short of armed conflict.  The examples in our own history are legion, including most recently the strikes under Bush I and Clinton in Libya, Sudan, Afghanistan, etc.  (Of course, there is dispute about whether some of these actions were legitimate self-defense; but for present purposes what’s important is that there’s no dispute that there have been many instance such historical cases where the claim of self-defense was justified.)

    I’ve always assumed that such self-defense actions are governed by IHL, in two important respects.  First, the many constraints of IHL apply — distinction, proportionality, necessity, no perfidy, no denial of quarter, etc.  Second, members of the armed forces of the state or non-state actor against whom the self-defense action is taken are legitimate targets (subject, of course, to the proportionality and necessity constraints that are a hallmark of legitimate self-defense), and therefore if the strikes are undertaken by a nation’s armed forces against such targets, they have combatant immunity and may not be prosecuted for murder under international law or the law of the state where the strike occurs.

    Is either of those premises mistaken?  If so, what are the authorities indicating that such IHL norms are inapposite to such self-defense measures — and what law *does* govern such measures?

  9. Dear Prof. Lederman,

    For what it is worth, I have an article due for publication around mid-year in the Yearbook of International Humanitarian Law that addresses your exact question. Having expressed the view that certain acts in national self-defence do not rise to the standard of an armed conflict, I conclude that the law of armed conflict cannot apply de jure. So, as a simple example, flattening/expanding bullets would be lawful. I go on to argue that the along with the jus ad bellum concepts of necessity and proportionality, those same legal terms need to be re-thought in the context of not just the resort to use of force but the actual application of that force to a particular target. I then suggest meanings for those terms. I also discuss whether compensation might be payable to bystanders who are injured or have property damaged.

  10. Very interesting, Ian.  Might I inquire *why* the rules of IHL would not apply?  Would there be any reason for nations not to insist upon the same protections?  Any state practice to the contrary?  For what it’s worth, it is longstanding DOD policy that all of its operations, in armed conflict or not, must comply with IHL — and my understanding is that they fully expect to be entitled to the combatant’s privilege in such cases.

  11. An article which does address the just/unjust issue : http://www.independent.co.uk/opinion/commentators/geoffrey-robertson-why-its-absurd-to-claim-that-justice-has-been-done-2278041.html

    If we come to the conclusion that it was legal yet unjust, the next step is to think how the legal context must be reformed so that next time similarly unjust actions can become illegal under the reformed international law.

  12. Marty,

    I think it’s important to distinguish between self-defensive actions against states and self-defensive actions against non-state actors.  Actions against states will always be subject to IHL, because any use of force, no matter how insignificant, will create an international armed conflict.  So IHL always applies to attacks against “the armed forces of the state” that is the object of self-defensive force.

    The situation is completely different, though, if self-defense is being invoked against a non-state actor.  Such actions are governed by IHL only if the hostilities objectively rise to the level of armed conflict. Of your examples, I think that IHL applied only to the strikes in Afghanistan; the others would have been governed solely by IHRL.

    Importantly, in the latter situation, where self-defense is being invoked against a non-state actor and the resulting hostilities do not rise to the level of armed conflict, it is indeed the case that the armed forces of the state acting in self-defense do not have combatant’s privilege.  Such a privilege never exists in a non-international armed conflict, much less in hostilities that do not qualify as armed conflict at all; the privilege exists only in international armed conflict.  In theory, then, a soldier fighting on behalf of the state acting in self-defense could be prosecuted for murder if he kills a member of the non-state actor.  But who would prosecute him?  The non-state actor obviously could not.  That leaves the state on whose territory the self-defensive action takes place.  It could indeed prosecute the soldier, but it is obviously unlikely that it would.

    Note, though, that this is not simply an academic question.  The absence of combatant’s privilege outside of international armed conflict explains why Italy had every right to prosecute the CIA officers who kidnapped Abu Omar from its territory.  If the officers had combatant’s privilege simply because the U.S. believed it was acting in self-defense against a non-state actor, such a prosecution would have been illegitimate — capturing the enemy is obviously permissible in armed conflict. But they did not have that privilege, because the kidnapping did not create an international armed conflict. The U.S. may have expected combatant’s privilege in that context, but it was not entitled to it.

  13. Marty,

    It is also important to recognize that states, not lefty human-rights groups, have traditionally insisted that only intense hostilities involving non-state actors (i.e., rebels) with a certain degree of organization are subject to IHL. When dealing with rebel groups, most states find IHL to be far too limiting; they want counterinsurgency operations to be a solely domestic matter.  (Most states don’t feel a particular need to comply with IHRL when dealing with rebels.) What makes the U.S. somewhat unique in that regard is that it wants to used armed force against non-state actors that are not traditional rebels and thus do not operate on U.S. territory.

  14. Kevin:  Thanks very much; that certainly tees up the issue cleanly!  Suffice it to say that your views about (i) the non-application of IHL to acts of self-defense short of armed conflict, and (ii) especially, the absence of any combatant privilege in a NIAC; are deeply contrary to U.S. understandings.

    Is there persuasive authority for either proposition?

  15. Prof Lederman,

    As a colleague of mine regularly accuses me of being, I took a black-letter, positivist approach to the issue. How could the laws of armed conflict (the law of war) legally apply to a situation that is not an armed conflict? As LOAC grants rights as well as imposes limitations, I think it is very important to realise that LOAC applies de jure only to an armed conflict.

    I have often discussed the DoD policy you mention with my US colleagues. As you point out, it is policy. It seems, ipso facto, that the US is of the view that the LOAC does not apply legally to those situations. I’ll claim that as State practice to show that LOAC does not apply de jure outside an armed conflict 🙂

    Importantly, the US can accept restrictions (eg, no flattening bullets, no perfidy) as a matter of policy, but cannot grant itself rights (eg, detention as a ‘PW’, shoot-to-kill based on ‘combatant status’) as a matter of policy.

    As Prof. Heller has brought it up, please note I also discuss in my article the issue of an equivalent to a combatant’s privilege for government forces in both a NIAC (I argue one exists, or at least should exist) and in article 51 actions (I argue one might exist, but with much less certainty). Without repeating my article in full, of course we need to distinguish in our arguments (which may or may not affect the conclusions) between the armed forces and other government forces (eg, CIA).

  16. Marty,

    Can you think of even one European country that accepts the U.S. position on those issues?  An African one?  An Asian one?  I can’t.  The ICRC also clearly rejects both positions.  These are foundational principles of IHL and always have been, if only because transnational conflict with non-state actors is a relatively new phenomenon; I think the burden is thus on the U.S. to show that state practice and opinio juris now support the existence of a customary rule that says IHL applies whenever a state uses armed force against a non-state actor in self-defense and that combatant’s privilege applies to such armed force.

  17. Kevin:  I do not mean to question your expertise — you know much more about these questions than I — but it would be very helpful to me if you could point to where the “ICRC also clearly rejects both positions” and to any authority that these “are foundational principles of IHL and always have been.”

    As I said in response to Ian, I can’t think of any obvious reason why nation states would not want such rules to apply to such self-defense and NIAC situations — of course, with any articulated adjustments that might be demanded by the distinct nature of such military actions — or why they would not customarily act in accordance with them, as the US military traditionally has done.  You raise the issue of civil wars.  But of course Lincoln/Lieber insisted, quite famously, that the laws of war do apply to such a conflict.

  18. Marty,

    With regard to the applicability of IHL, I’d point you to Article 1 of the Second Additional Protocol:

    Art 1. Material field of application

    1. This Protocol, which develops and supplements Article 3 common to the Geneva Conventions of 12 August 1949 without modifying its existing conditions of application, shall apply to all armed conflicts which are not covered by Article 1 of the Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) and which take place in the territory of a High Contracting Party between its armed forces and dissident armed forces or other organized armed groups which, under responsible command, exercise such control over a part of its territory as to enable them to carry out sustained and concerted military operations and to implement this Protocol.

    2. This Protocol shall not apply to situations of internal disturbances and tensions, such as riots, isolated and sporadic acts of violence and other acts of a similar nature, as not being armed conflicts.

    Article 1(2) explicitly limits the application of IHL outside of international armed conflict to hostilities that involve a certain level of intensity and continue for a certain length of time.  Individual acts of self-defense, such as your examples of Libya and the Sudan, clearly do not qualify as armed conflicts under that definition.  AP II has been ratified by 165 states.  Does that not clearly indicate that the U.S. position is inconsistent with customary international law?

  19. Marty,

    With regard to combatant’s privilege, see pages 8 and 10 of this ICRC Report.  (It doesn’t allow cut and paste.)

  20. Kevin:  Article 1(2) does not “explicitly limit the application of IHL to hostilities that involve a certain level of intensity and continue for a certain length of time” and to NIACs covered by APII, nor does it preclude the application of IHL to acts of self-defense not rising to the level of armed conflict.  Instead, it merely provides that the treaty requirements of APII itself are so limited in scope:  “This Protocol . . . shall apply . . . .”  Customary IHL is left unaffected — and my assumption is that such customary law applies both to acts of self-defense and to NIACs.

  21. Marty,

    AP II’s intensity and duration requirements are also part of the Rome Statute (Article 8(2)(f)), which has been ratified by more than 110 states, and the ICRC has officially taken the position that the intensity and duration requirements apply to Common Article 3 of the Geneva Conventions, as well (see page 3-5 of this report), which have been ratified by every country in the world, including by the U.S.  The ICTY has also adopted the intensity and duration requirements in a number of cases; the cites are in the ICRC report.  So on what basis do you claim that the U.S. position reflects customary international law, not the ICRC’s position?

  22. To step back for a minute and put this discussion in broader focus:  As I’ve argued to Kevin in the past, I am frankly surprised that human rights supporters are so reluctant to acknowledge that IHL applies in these cases — namely, to acts of self-defense short of armed conflict, and to NIACs.  The application of IHL in such cases is overwhelmingly a positive thing, bringing with it as it does substantial humanitarian protections for civilians and soldiers alike.  That’s why some in the Bush Administration were so eager to deny its application (and the application of Common Article 3), and why it was such a momentous and salutary development when the Court held in Hamdan that CA3 does apply.  If international law were to settle on the view that IHL does not apply in such contexts, I have little doubt that nation states would feel far less constrained, and act in a much less constrained and humanitarian manner, in their use of force in such contexts.

    Of course, the flip side, of sorts, is that although customary IHL imposes numerous very important constraints on the use of force, it also establishes combatant immunity for uses of force by state armed services where such use of force complies with IHL.  As suggested upthread, it’s not so obvious that this is important as a practical matter, since the risk of prosecution for murder in such cases is so small.  Nevertheless, state militaries understandably (and, in my view, reasonably) consider it a critical condition for the application of the many significant constraints of IHL — constraints that have a very important, and humanitarian, impact on the conduct of acts of self-defense and the conduct of NIACs.

    All of which is to say that those who care deeply about human rights should be very careful what they wish for when they argue that IHL does not and should not apply to the use of force in self-defense and in NIACs.

  23. Kevin:  With particular respect to your comment about duration and intensity, I did not write, nor suggest, that IHL applies to any and all uses of military force.  All I suggested was that where such use of force satisfies jus ad bellum requirements — in particular, where there is (i) a NIAC (in which case there is the requisite intensity and duration, even in cases where APII does not apply), or (ii) where a nation acts in legitimate self-defense (where there might not be such intensity and duration), the nation must comply with the jus in bello of IHL — and where its armed forces do so, they are entitled to the combatant’s privilege.

    I am unaware of any authorities establishing that the use of force in such cases need not comply with the jus in bello, or that armed forces who so comply can still be guilty of murder.  Not saying there’s no such authority out there — only that I’m not aware of it.

  24. A test for any argument based on the non-state status of the targeted person should be what happens when that non-state person happens to be hiding inside the borders of the United States and the killing action takes place within the borders of the United States. Does the principle of separation of powers remain unscathed ?

  25. I hope we can agree that combatant’s privilege cannot exist outside of IHL (international armed conflict, to be precise, but let’s put that aside for now).  In your self-defense scenario, IHL applies and combatant’s privilege exists only because the act of self-defense is legitimate under Article 51 — under the jus ad bellum.  By implication, therefore, if the soldiers killed during the course of an illegitimate act of self-defense, IHL would not apply and the soldiers would not be entitled to combatant’s privilege.  But that makes the content of the jus in bello — IHL — dependent upon the jus ad bellum.  Do I need to provide a cite for the independence of those two legal regimes?  I provided three in the post — the Farben, Krupp, and Ministries tribunals, all of which held in no uncertain terms that the legitimacy of an invasion is irrelevant to the applicability and content of the laws of war.

  26. Kevin:  Alas, I think we’re now in an infinite loop.  No, we don’t agree that the combatant’s privilege cannot exist outside of IHL, let alone not outside IACs.

    And no, I did not deny that IHL might even apply in situations where the use of force was unjustified, such as in the FarbenKrupp, and Ministries cases.  My point is simply that state armed forces are not immune from the requirements of IHL (or denied its protections) where, at a minimum, the use of force is lawful in cases of self-defense and NIAC.  Is there any authority indicating that in such cases, armed forces are not bound by, e.g., the IHL requirements of humanity and necessity and distinction, or that they need not comply with the prohibitions on perfidy, denial of quarter, outlawry, etc.?  Or that they can be prosecuted for murder, consistent with international law, where they have complied with such IHL norms?

  27. forgot to add:  And perhaps just as importantly, as I discuss a couple of comments ago, even if the law were uncertain on this question (and I’m still not convinced), why would it be in the interest of human rights proponents such as ourselves to insist that IHL does not apply in such cases?  I fear that nothing good would come of such a view if it were to prevail.

  28. Kevin and Marty,

    If I may, the reason that the treaties cited by Kevin are limited in their application is that states originally wanted it that way.  If you check the negotiating histories, states DID NOT want to be bound by IHL unless they were assured of some willingness and ability for non-state actor compliance.   Thus, STATES created the protracted hostilities of sufficient intensity and “sufficient organization” requirements. 

    What states did not intend, I think (and in spite of the case law of international tribunals), is filling of the legal lacunae in this framework — meaning for a response to armed attacks by non-state actors not amounting to armed conflict — to be governed by human rights law, particularly extraterritorially.  In such cases, states may observe IHL as a matter of policy or by analogy but had no requirement to do so as a matter of law.  This, I think, is Jordan Paust’s position, and somewhat reflects the U.S. position (depending, perhaps, upon the administration).

    While I respect Kevin immensely, he frequently argues, without citation, that no European country views the law this way.  Absent a thorough study, I can’t bring myself to fully agree.  I agree that a great many European academics, particularly those with whom Kevin probably associates and some who have spent time at the ICRC, agree with Kevin on these points.  I have met others, prominent ones, who don’t or don’t completely.  I am also less sanguine that European governments widely hold to his views. 

    Regardless of the current state of customary international  law on this point, I think the U.S. view will ultimately prevail.  I think this because non-state actors exploiting modern technology can cause much more damage than at critical points in the development of conventional IHL on these issues.  This expansion of capacity, particularly in the cyber world where one man can create an “army” of computer bots, but also in the physical world where nuclear and other technology might be increasingly available (and concealable), will cause state practice to solidify on a more expansive scope of IHL.

    This is my guess.  The key in this future will be to identify the nature of non-state actors properly subject to IHL targeting in an act of national self-defense, as well as related epistemic issues.

    On the combatant immunity point, in my humble opinion, it is more nuanced than either of you suggest.  Official immunity can exist in extraterritorial aspects of non-international armed conflict.  The question is whether it takes the form of “combatant immunity” or some other form (or perhaps I should say “derivative form”) of sovereign immunity.  Dapo Akande had a great post on this over at “EJIL Talk!” in response to the Italian court’s verdict mentioned by Kevin.  Further, in a purely internal , non-international armed conflict, international law doesn’t really provide “combatant immunity.”  The source of “immunity” for violence forming a part of such hostilities must necessarily come from domestic law, and is more likely to take the form of “public authority.”  In the unique U.S. “common law of war,” it is probably properly considered combatant immunity, but because it is so considered in our domestic common law.  That is not what international law would necessarily call it…though state practice isn’t clear on this point either so far as I can tell.

    For what it’s worth, that’s my take on these issues.

  29. And please forgive my many typos…

  30. Kevin, Marty and John,

    I hope my comment is not arriving too late for your reactions.  Kevin cites APII and the Rome Statute with large numbers of signatories (over 160 and 110 respectively) as evidence that these treaties can be recognized as customary international law.  However customary law must be supported by state practice as well as treaty signatures.  I am unaware of any situation in which states that have actually been involved in conflicts with non-state actors have eschewed the right of self-defense against such parties, even when they had to cross international borders to exercise that right.  Colombia (a party to both APII and Rome) crossed the border into Ecuador to strike FARC camps there.  Turkey crossed into Iraq to strike the PKK.  Israel crossed into Lebanon to strike Hezbollah.  Back in the 1970’s the US crossed into Cambodia and Laos to strike the Viet Cong.  More recently the US has entered Afghanistan to go after al Qaeda (with UN support) and has entered Pakistan without Pakistani permission in pursuit of al Qaeda as well.  

    Plenty of states may have signed APII and the Rome Statute, but I am not aware of any nation that has actually been involved in an armed conflict with a non-state actor that has not exercised self-defense against that non-state actor, even when it meant crossing an intnernational boundary to do so.  Therefore it would seem that state practice strongly supports the idea that a nation may exercise self-defense against a non-state actor, even when that actor seeks refuge across an international boundary line.

    If I am missing examples of state restraint in the context

  31. Sorry.  To finish I just ask for any counter examples in which states involved in armed conflicts with non-state actors have recognized international boundaries as legally foreclosing their ability to strike the non-state actors in self-defense.  I am not aware of any, but they certainly may exist.

  32. Michael,

    As I said in the post, I completely agree with you that Article 51 gives states the right to act in self-defense against non-state actors.  I am simply pointing out that whether that act triggers IHL is determined objectively, pursuant to the customary definition of non-international armed conflict — reflected in AP II and the Rome Statute — not by reference to whether the use of force against the non-state actor satisfies the requirements of Article 51.  The two issues are completely separate; Marty’s argument to the contrary conflates the jus ad bellum and the jus in bello.

  33. I’m not following what this all really hinges on.  Imagine the unlikely scenario in which the U.S. elects to employ a drone a attack as the means to kill bin Laden, and successfully does so while injuring no one else.  Is your analysis different?  Is there a number of civilians or others killed who are not party to armed conflict that you would say would make this operation illegal?  Is it a matter of degree of certainty that the U.S. must have that no more than x number of noncombatants are likely to be killed in a given strike?  Or would simply any operation intended to kill bin Laden been legal?  Presumably that’s impossible to say, because at some point some level of destruction of human life will be out of proportion to whatever is being retaliated for.  But exactly against what is propostionality measured.  Is it measured on a by0target basis, i.e. bin Laden was responsible for at least 3000 American deaths, so up to 3000 incidental deaths to his killing would be proportionate?  How are any of these thresholds and comparisons – i.e. the triggering of IHL and proportionality – actually measured?

  34. Also what comments would Kevin have about this article: http://afpak.foreignpolicy.com/posts/2011/05/04/the_bin_laden_aftermath_abbottabad_and_international_law, where an author whom I think is known here argues, among a lot of other things, that, “On May 2, no fighting was going on in Pakistan that would rise to the level of “armed conflict” as defined under international law[…]”?

  35. If International law makes the Abbottabad raid legal, doesn’t it make the French operation in Auckland (New Zealand) in 1985 (sinking of the Rainbow Warrior) simultaneously legal ?

  36. Dear Gerbert,

    I do not believe so. I doubt that it would be a good argument to suggest that France was involved in a NIAC with Greenpeace. Nor does it seem arguable that the Rainbow Warrior was involved in (even in the anticipatory sense) an armed attack on France or its national interests.

  37. Kevin,

    Thanks for the response.  Let me try to reiterate your position and tell me if I am getting it right.  Article 51 self-defense against non-state actors requires the existence of an armed conflict, as opposed to self-defense against state actors which merely requires an armed attack.  In the bin Laden example you find that there is an armed conflict between al Qaeda (original) and the US that bin Laden is participating in, therefore the self-defense jus ad bellum justification for the killing is valid.  Is that correct?  If so, would the killing have been equally valid if bin Laden had been in Yemen?

    To clarify one point from my post that you were commenting upon.  My reference to the SEALs and the manner in which the operation took place was merely done to clarify the fact that the US was treating this as a military operation not a law enforcement operation.  I agree with you that the mere fact that the US characterizes it that way does not make it so legally (your Syrian tank example).  My purpose in mentioning that was to answer MEO’s claim that the US undertook this as a law enforcement operation.

    Thanks for your responses. 

  38. Michael,

    No, my argument is precisely the opposite of that.   Article 51 self-defense (a jus ad bellum issue) in no way requires the existence of armed conflict (a jus in bello issue).  Article 51 permits self-defense against non-state actors because, as you point out, states have consistently and uniformly interpreted Article 51 that way.  Conversely — and this is my point — whether Article 51 justifies a use of force (a jus ad bellum issue) in no way determines, and is indeed not even relevant to, whether an armed conflict exists where the self-defensive force is used (a jus in bello issue).  Some actions taken during legitimate uses of force in self-defense against non-state actors will be governed by IHL: when they take place during hostilities that satisfy the customary definition of NIAC.  Other actions taken during legitimate uses of force in self-defense against non-state actors will be governed by IHRL: when they take place during hostilities that are not sufficiently intense or protracted to trigger IHL.  Which regime applies has nothing to do with whether the use of force is legitimate under Article 51; the jus ad bellum and jus in bello are separate.

  39. Hi Kevin,
    Thanks for sharing your views. Just for my understanding of the legality of OBL’s killing: Leaving ius ad bellum aside and focussing on ius in bello, if we assume that there is a NIAC between the US and AL Qaeda (involving OBL) – I can live with that reasoning – doesnt the legality of the killing then depend on the specific circumstances of the killing? I mean all it says is that OBL is a legitimate target, so could be killed unless he laid down arms, was detained or clearly surrendered, no? The current info from US we have is that he was unarmed but that there were weapons within his reach – if that is true, I could leave with the reasoning that as a legitimate target he could be killed legally. If he clearly surrendered though (being out of reach of weapons) I think it would have been illegal. What do you think?

    Thanks for your reactions


  40. Dear Professor Kevin Jon Heller,

    According to you first post : ”
    “The bottom line: yes, killing bin Laden was legal.  But it was legal because the operation that killed him complied with IHL, not because it was permitted by Article 51. The latter issue is relevant only to whether Pakistan has the right to complain about the United States’ violation of its sovereignty.”

    as you argued,IHl doesnot apply to NIAC and situations not amounted to armed conflict, how can American troops have combatant privilege to kill Laden?

    Or there are other reasons to have such killings legal?

    Thank you.

  41. WCL,

    If Pakistan had captured the soldier who killed bin Laden, it could have prosecuted him for murder.  There is no combatant’s privilege in NIAC.  That obviously would have been a political non-starter, but nothing in international law would have prohibited the prosecution.

  42. I disagree with both Lewis’ and Heller’s analysis.


    If one argues that OBL ‘s killing falls under IHL, one can not do that without establishing that a CURRENT armed conflict between both the US and Al-Qaida existed at the time of the use of force against OBL. Its my understanding that the US are not currently engaged in an armed conflict on Pakistani territory. And in Afghanistan enemy combatants are at time  (afghan) Taliban not Al-Qaida.

    The “war on terror” is in general sense a political doctrine, which by itself doesn’t establish circumstances falling under the term “armed conflict” necessary for IHL application.

    The idea that this a case of Art. 51 UN Charta is a strange one. Leaving aside that by prevailing opinion it does not apply to non-state actors: Use of force under Art. 51 demands a current or at least imminent threat and the force applied has to be necessary and appropriate to end the attack. In the words of Webster/Caroline: “(The threat has to be) instant, overwhelming, and leaving no choice of means, and no moment for deliberation”.
    I doubt that the general characterization of OBL being a potential dangerous person (if he still was at all) would fall under that legal term.

    About 65 years ago America gave proof to the world of its moral superiority by bringing the Nazi monsters who murdered millions of people to justice through a fair and public trial, instead of doing ad-hoc executions. By that a clear line between governments bound by law and those of unlawful criminals was drawn.
    If we abandon those principles, then terror has defeated us.


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  3. […] Jon Heller, at Opinio Juris, shares his thoughts on the legality of killing bin Laden. Heller maintains that: “I have no doubt that killing […]

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