Jeffrey LewisDOD Law of War Manual and Nukes

The Defense Department released a Law of War Manual in June that says some interesting things about how the United States views legal questions about the use of nuclear weapon.

Legal perspectives are terribly important in the United States. I observe that the United States tends to think about nuclear weapons in a far more legalistic manner than other states, whether friend or foe.  I was in one meeting where an American participant talked about the legal constraints on a President contemplating the use of nuclear weapons when a French colleague laughed.  “We would throw the lawyers out the room!” he said.  That struck me, since of course in the United States that would mean the President would have to throw himself out of the room.

For the past couple of years I’ve been working on a big idea that looks at how the United States might alter its approach to nuclear deterrence, one that is rooted in legal questions about military necessity and the use of nuclear weapons.  But I am getting ahead of myself!  There is still the issue of the June 2015 Law of War Manual.

Fortunately, Dr. Heather Williams (@heatherwilly) has kindly agreed to send along a very useful analytic summary.

Nuclear Weapons and the Law of War Manual in Six Points

Heather Williams, King’s College London

While we were all distracted by the Iran deal (see last nine ACW posts), the US Department of Defense released its Law of War Manual back on June 12, 2015. Heavily footnoted legalese may not seem quite as gripping as the down-to-the-wire drama of negotiations in Vienna, but there are some good nuggets in there with respect to the legality of nuclear weapons use and nuclear deterrence. This comes after a controversial NPT Review Conference in May, and legal justification for nuclear weapons runs up against increasing pressure from some states in the humanitarian impacts initiative for a nuclear weapons ban.

Much of the Manual is based on the 1977 Additional Protocol I (AP I) to the Geneva Conventions (not to be confused with the IAEA Additional Protocol); however, the United States never signed up to AP I, nor does AP I apply to nuclear weapons. At first glance, the Manual only devotes two pages and 373 words to nuclear weapons. But did I mention the footnotes? Those two pages contain an additional 1034 words in the footnotes, but, more importantly, the 1996 ICJ Advisory Opinion is heavily featured throughout the entire Manual.

Here are some highlights:

1. Non-nuclear weapon states cannot impose customary international law when it comes to nuclear weapons. Interests of nuclear armed states take precedent because they are “specially affected.” A footnote on page 32 cites the ICJ Opinion: “Evidence of a customary norm requires indication of ‘extensive and virtually uniform’ State practice, including States whose interests are ‘specially affected.’ … With respect to the use of nuclear weapons, customary law could not be created over the objection of the nuclear-weapon States, which are the States whose interests are most specially affected.”

2. Non-use of nuclear weapons does not translate into customary international law. This is because lack of use is not the result of a legal opinion or ruling, and, to cite the 1996 ICJ Opinion, “if nuclear weapons have not been used since 1945, it is not on account of an existing or nascent custom but merely because circumstances that might justify their use have fortunately not arisen.”

3. As long as nuclear weapons exist their use would be “authorize-able”, or justifiable, unless there was a legal prohibition with the support of nuclear-armed states (see point 1): “Like other aspects of the law of war, the rules relating to weapons are generally characterized as prohibitive law forbidding certain weapons or the use of weapons in certain instances rather than positive law authorizing the weapon or its use. The lawfulness of the use of a type of weapon does not depend on the presence or absence of authorization, but, on the contrary, on whether the weapon is prohibited.”

4. Nuclear weapons use would not necessarily be disproportionate. This is where things get interesting because it is talking about specific conditions of use, rather than nuclear weapons in the abstract. As part of the ICJ case, the United States submitted a statement, which is cited on page 314: “Whether an attack with nuclear weapons would be disproportionate depends entirely on the circumstances, including the nature of the enemy threat, the importance of destroying the objective, the character, size and likely effects of the device, and the magnitude of the risk to civilians. Nuclear weapons are not inherently disproportionate.” If nuclear weapons were used in response to a nuclear attack, for example, that would be proportionate, assuming similar yields and targets.

5. Nuclear weapons use would not be illegal based solely on the humanitarian and environmental effects. International law prohibits “asphyxiating, poisonous, or other gases, and all analogous liquids, materials, or devices’. However, if these effects are a by-product rather than the primary intent of a weapon, that weapon could still be considered legal: “the rule is understood only to prohibit weapons whose prime, or even exclusive, effect is to poison or asphyxiate. Thus, for example, smoke, flame, napalm, conventional explosives, and nuclear weapons are not covered by this rule, even though these weapons may produce asphyxiating or poisonous by-products.” These humanitarian and environmental effects should not be ignored, but rather consideration should be given to the specifics of potential use and how to minimize collateral damage in the extreme conditions when nuclear weapons would be used.

6. Nuclear weapons use would not necessarily be indiscriminate, another contention of just war proponents: “There is no general prohibition in treaty or customary international law on the use of nuclear weapons…. nuclear weapons must be directed against military objectives. In addition, attacks using nuclear weapons must not be conducted when the expected incidental harm to civilians is excessive compared to the military advantage expected to be gained.” Again, this raises more interesting questions about targeting and whether or not lower-yield nuclear weapons would be more humane.

Still with me? If so, let’s talk about what is not in the Manual, namely a discussion of arms control treaty obligations- a rather strange omission for a document on international law. The Manual acknowledges US non-proliferation responsibilities, along with agreements to reciprocally reduce its arsenal, but on p. 394 it says, “Some of these agreements may not apply in times of war. Guidance on nuclear arms control agreements is beyond the scope of this manual.” Fair enough, but then p. 925 engages in a discussion about the specifics of the Outer Space Treaty so it seems like an attempt to deflect difficult questions about disarmament. On that note, most noticeably absent is any mention of US commitments to “general and complete disarmament” under Article VI of the NPT. One possible explanation for this is that the Manual is about the laws of war rather than treaty law, which could be discarded in times of war and “supreme national interest”- a fine line, indeed.

Proponents of a nuclear weapons ban are likely to pick up on the following point on p. 72: “Certain prohibitions and certain other rules in the law of war that reflect customary international law have been described as reflecting ‘elementary considerations of humanity.’ These ‘elementary considerations of humanity have been understood to be ‘even more exacting in peace than in war.’ Thus, these legal standards, at a minimum, must be adhered to in all circumstances.” And herein lies the heart of the debate between nuclear deterrence, which requires a credible threat of use of nuclear weapons, and humanitarian approaches to war. Ideally, the humanitarian impacts initiative would provide a forum for diverse discussion of these issues and seize the opportunity provided by the release of the Law of War Manual.



  1. Jonah Speaks (History)

    I doubt that international law would be the main consideration, either for the U.S. or any adversary, when contemplating or retaliating against either a nuclear use or a nuclear strike. To be effective, an international law or treaty must constrain nuclear arms or nuclear behavior before war begins, rather than try to locate and punish law-breakers after the war ends.

    The massive explosive power of nuclear weapons can exterminate multiple cities and civilian populations within a very short period of time. This is unlike a conventional war between similarly endowed adversaries, where it would likely take significant time and great expense to do similar damage.

    Among nuclear strategists, counter-value is often favored over counter-force, that is “Killing people, good; killing weapons, bad.” This is because counter-force may lead to a first-strike advantage, making a rapid descent into nuclear war more likely. This is a complete inversion of the just war principles developed for conventional war.

  2. kme (History)

    This seems to be nothing more than an illustration of the adage that a good lawyer will argue whatever you pay them to argue.

  3. AEL (History)

    When did the USA get so legalistic? In LeMay’s time, the USAF was pretty cavalier. Their basic assumption was that they would be would be the ones to initiate strategic nuclear strikes. Further, their attitude towards things like launch codes (00000000) seems anti-legalistic.

    And yet now, the lawyer/warhead ratio seems to have completely flipped.

    What happened?

  4. Magpie (History)

    If a President gave an illegal order, would it be refused?

    • Jonah Speaks (History)

      To be sure, I see nothing in the above description of the DOD manual that clearly makes any nuclear use illegal under international law, though some disproportionate uses might be (fuzzily) illegal. Hence, to declare any Presidential nuclear order illegal, we must consult domestic U.S. constitutional, treaty, or statute law.

      One historical example comes to mind. The August 22, 1974 Washington Post reported that during the final days of the Nixon administration, Defense Secretary James Schlesinger and the Joint Chiefs of Staff had “kept a close watch to make certain that no orders were given to military units outside the normal chain of command.” Ostensibly, this was to prevent “some sort of action against Congress.”

      Let’s give the story a different twist. The President is despondent, maybe even suicidal, and decides to leave the world in flames. The President orders a nuclear attack on the Soviet Union. The Soviet Union has undertaken no hostile act against the U.S. or its allies to merit this nuclear attack.

      Arguably, the order amounts to a declaration of war by the President alone, in violation of the U.S. Constitution. Would such an order be illegal, or merely crazy? Given the story in the Post, it appears likely that the Joint Chiefs would not have carried out this hypothetical order.

  5. Gregory Matteson (History)

    The US has a long history of legalistic thinking, along with a folk rejection of the same, both in Government and in Religion.
    The above outline is to me a frightening reversal of the movement up till now in the 21st century, represented by the MOAB (Whether that acronym is interpreted as Mother Of All Bombs, or Massive Ordinance Air Burst), and the peevish Russian response with the Father Of All Bombs (does that work better in Russian?). The message of those weapons to our own Generals, as well as “theirs” was, and remains, that advanced countries can raise the threshold of need to use tactical nuclear weapons to just about any arbitrarily high level. The Massive Ordinance Penetrator just puts an exclamation point on that message.
    As for Magpie’s question: that is one of the breaking points in our Constitution, and ones modeled on it. If it comes to a showdown between branches of government, it becomes a question of whose orders get obeyed. Hmmmm, the precedent of Andrew Jackson was that it was the President’s illegal orders that were obeyed. I’m talking about the Cherokee Removal.

  6. jeannick (History)

    On the US government at war and legalism
    the best legal twisting I can think of is Abraham Lincoln freeing slaves in territories under confederate control
    it didn’t apply to union states or part of confederate states occupied by Union troops
    it led to journalists claiming it fred those that it couldn’t and didn’t thoses that it could .

    The expression “mother of all ” is an old Arabic expression ,the most important contribution of Saddam Hussein to Americanese.
    the traditional superlative Russian equivalent is “czar of”
    on the Kremlin ground there is the Czar cannon and the Czarina bell , they also detonated the czar bomba , arguably the largest nuclear weapon test in history

  7. Bill (History)

    Looks like the Pentagon lawyers reject the notion that a nuclear taboo (“existing or nascent custom”) has had any constraining impact on nuclear use over the decades. But as someone has noted, lawyers will write what their client wants.

    On Emancipation Proclamation: it was not legal twisting. it didn’t apply to union states because slavery had been abolished in all of them years before the Civil War. As for territory already occupied by Union forces, the Constitution and war powers did not allow freeing enslaved people in territory under federal control. Nevertheless, emancipation was already taking place. Through their own volition enslaved people were quitting the plantations and following the Union army (and in many instances enlisting in it). And no one was enforcing the slave laws, least of all Lincoln. As the Union army advanced into the South the same pattern would repeat itself. Slavery as an institution was destroyed before the 13th amendment, thanks to Emancipation proclamation backed by Union successes.

    • Jeffrey (History)

      Bill’s account of the Emancipation Proclamation discussion is an important reminder that turning points are often narrow textually but broad and irreversible in implication. Thanks.

  8. Bill (History)

    thanks Jeffrey

    I realize I made an overstatement because of special circumstances relating to border states.

    if you would change “in all of them” to “in the North” it would be better

  9. Bahram (History)

    Jeff, The comments for your podcast of of July 15 have not been posted yet. I posed a question there, which you may choose to answer or ignore.

    • Jeffrey (History)

      I don’t moderate them, but I looked and don’t see yours.

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