The Rome Statute Does Not Criminalise Chemical and Biological Weapons

by Kevin Jon Heller

Over the past week, two posts at Just Security have argued that the ICC can prosecute the use of chemical and biological weapons as a war crime, even though they — unlike other types of weapons — are not mentioned in Article 8 of the Rome Statute. The first post was written by Ralf Trapp, who argued as follows:

Furthermore, there are the provisions of the Rome Statute of the International Criminal Court (ICC). Even though it does not use the terminology of the CWC (“chemical weapons”), there is no doubt that the terms “employing poison or poisoned weapons” and “employing asphyxiating, poisonous or other gases, and all analogous liquid, materials or devices” found in the list of war crimes under the statute’s Article 8 would squarely apply to the use of chlorine or mustard gas as a weapon of war. Any such use would consequently come under the jurisdiction of the ICC.

Trapp does not even acknowledge any other interpretation of Article 8. By contrast, the second post, written by Alex Whiting, admits that a different interpretation is possible. But Whiting nevertheless sides with Trapp, citing an earlier post by Dapo Akande at EJIL: Talk!:

The Rome Statute originally included a direct ban on chemical and biological weapons, but it was dropped at the same time as a ban on weapons causing unnecessary suffering was narrowed to apply only to those weapons listed in an annex (which does not exist because the States Parties never adopted one). This narrowing was done to avoid having the broader provision apply to nuclear weapons. The direct chemical and biological weapons prohibition was then dropped, apparently because some negotiators thought that there should be parity in approach to nuclear weapons (possessed by wealthy nations) and chemical and biological weapons (the more likely option for poorer countries). The claim that that the Statute therefore does not cover chemical and biological weapons was reinforced by Belgium’s efforts at the ICC Review Conference in Kampala in 2010 to amend the Statute to include a ban on chemical and biological weapons, indicating that there was an understanding among at least some States Parties that the Statute as written did not already do so.

But Akande persuasively argues (reinforcing what Trapp intuits) that the language in the Statute prohibiting poisonous and asphyxiating gases and analogous liquids, materials, and devices plainly applies on its own terms to most — if not all — chemical and biological weapons. Since the treaty text is clearly written, there is no need to consider the history of its drafting, per the Vienna Convention on the Law of the Treaties. In this case, the difficulty with relying on the negotiation history in the first instance is that it is highly indeterminate: Assessing what 120 countries “intended” when they adopted the Rome Statute is nearly impossible, and therefore the plain language of the treaty should govern when it is clear, as it is here.

I disagree with Trapp and Whiting. I won’t rehash the arguments I made in response to Dapo’s post; interested readers can see our exchange in the EJIL: Talk! comments section. But I do want to flag three critical problems with the argument advanced by Trapp and Whiting: one factual, one theoretical, and one political.

The factual problem is that this is simply not a situation in which the drafting history is “highly indeterminate.” Few drafting disputes are as well known as the dispute over the criminalisation of nuclear weapons, chemical weapons, and biological weapons. And as Whiting’s own account makes clear, we know with absolute certainty that not enough states favoured criminalising the use of chemical and biological weapons — because the proposal to criminalise them failed. The reason why states opposed criminalising their use is irrelevant; I’m quite sure that some may have wanted to reserve the right to use them, while others would have been happy to criminalise their use but did not want to alienate the nuclear states. All that matters is that it is undisputed states tried and failed to criminalise the use of chemical and biological weapons.

It does not matter, then, whether “[a]ssessing what 120 countries ‘intended’ when they adopted the Rome Statute is nearly impossible.” What matters is whether we know how 120 states understood Art. 8 of the Rome Statute. And we do: regardless of whether they were elated by or disappointed in the outcome of the negotiations, all 120 were fully aware that the Rome Statute they were adopting did not criminalise the use of biological or chemical weapons. Indeed, that is precisely why Trapp and Whiting want to rely on the supposedly “plain meaning” of the war crime of “[e]mploying asphyxiating, poisonous or other gases” — they cannot cite even a single state that voted for the Rome Statute believing that, despite the rejection of the proposal to include biological and chemical weapons in Art. 8, the use of biological and chemical weapons was nevertheless a war crime.

The theoretical problem with Trapp and Whiting’s position is that, in fact, the VCLT does not require interpreters to ignore the Rome Statute’s clear drafting history in favour of the supposedly “plain meaning” of the war crime of “[e]mploying asphyxiating, poisonous or other gases.” Most obviously, Art. 31(4) of the VCLT, which is part of the “General Rule of Interpretation,” specifically provides that “[a] special meaning shall be given to a term if it is established that the parties so intended.” Art. 31(4) directly acknowledges the importance of intention in interpreting a treaty, thus rejecting Whiting’s radical skepticism toward drafting history. Moreover, as Mark Villiger notes in his seminal commentary on the VCLT, special meanings are particularly likely to be found in “in technical or historical contexts or in specialised treaties.” Few treaties are as technical or specialised as the Rome Statute, whose provisions must always comply with the principle of legality. Indeed, it is difficult to imagine anything less susceptible to a “plain meaning” interpretation than an expression like “[e]mploying asphyxiating, poisonous or other gases and all analogous liquids, materials or devices.”

It is also worth noting that Art. 31(4) is not the only provision in the VCLT that acknowledges the importance of drafting history. As Julian Davis Mortenson points out in his brilliant AJIL essay “The Travaux of Travaux: Is the Vienna Convention Hostile to Drafting History?”, the drafters of the VCLT were generally hostile to the idea that interpreters should take a “plain meaning” approach to treaty interpretation:

To the contrary, the drafters repeatedly reiterated that any serious effort to understand a treaty should rely on a careful and textually grounded resort to travaux, without embarrassment or apology. They themselves leaned heavily on travaux when debating any legal question that turned on the meaning of an existing treaty. And each time a handful of genuinely anti-travaux delegates attempted to restrict the use of drafting history to cases where the text was ambiguous or absurd, those efforts were roundly rejected. To be clear, the VCLT drafters embraced drafting history with full knowledge of its complications. They were intimately familiar with the standard challenges, including the difficulty of deciding which documents to include, the risk that negotiators would abusively insert self-serving statements, the problems of unequal access to the documentary record, and the inscrutability of some historical materials even when approached with diligence and sensitivity. But lengthy and lively consideration of all these problems did not dissuade the drafters from their decision.

The understanding that emerged was of interpretation as a recursive and inelegant process that would spiral in toward the meaning of a treaty, rather than as a rigidly linear algorithm tied to a particular hierarchical sequence. In any seriously contested case, interpreters were expected automatically to assess the historical evidence about the course of discussions, negotiations, and compromises that resulted in the treaty text—in short, the travaux. The modern view that Article 32 relegated travaux to an inferior position is simply wrong. The VCLT drafters were not hostile to travaux. They meant for treaty interpreters to assess drafting history for what it is worth in each case: no more, but certainly no less.

Finally, there is the political problem with Trapp and Whiting’s position: namely, that although replacing carefully-negotiated meanings of Rome Statute provisions with much more expansive “plain meanings” will no doubt please activists, it will also inevitably alienate states. A state agrees to be bound by a treaty because it approves of (or can at least live with) its treaty obligations; if a treaty imposes obligations that are not acceptable, the state will refuse to ratify it. States thus expect treaty provisions to mean what the drafters of the treaty intended them to mean, not what activists see as the “plain meaning” of those provisions. Indeed, the mere invocation of “plain meaning” in the context of a controversial treaty provision is almost always a dead giveaway that activists are trying to go beyond what states were willing to accept.

Will the proliferation of activist “plain meaning” interpretations immediately cause states to abandon the ICC? Of course not. Most ICC member-states are sufficiently committed to the Court to overlook interpretations of the Rome Statute that do not accord with their expectations — at least insofar as an activist interpretation does not affect them too directly. (The Trial Chamber’s problematic interpretation of amended Art. 68, which is designed to make Ruto easier to convict, may well be the straw that broke Kenya’s back.) But what about states that have not yet joined the ICC — states whose membership the ICC desperately needs to become more than just a court for prosecuting rebels and deposed heads of state? Is it not reasonable to assume that skeptical states will become even more skeptical of the ICC each time the judges adopt a “plain meaning” of a provision in the Rome Statute that is the exact opposite of the meaning the drafters carefully negotiated?

Indeed, the danger of such activist interpretations is nowhere more evident than in the context of chemical, biological, and nuclear weapons. The ICC member-states that opposed the criminalisation of chemical and biological weapons, the less powerful states, are simply out of luck if the judges decide to read the war crime of “[e]mploying asphyxiating, poisonous or other gases” in the manner that Trapp and Whiting advocate. If those states did not want the use of chemical and biological weapons to be criminal, they should have made sure the Rome Statute did not include any terms — like “poisonous” or “asphyxiating” — that could be plausibly interpreted to include chemical and biological weapons. Silly less powerful states!

But the powerful states, the ones the ICC desperately needs, have not yet joined the Court — the US, Russia, China, India. And guess what those states have in common? They all possess nuclear weapons. What will the ICC say to them if the judges decide to criminalise chemical and biological weapons even though the drafters of the Rome Statute specifically refused to criminalise them? It could not assure them that the Rome Statute would still permit the use of nuclear weapons. After all, exposure to nuclear material is called “radiation poisoning” for a reason. Do do we really think states like the US, Russia, China, and India will not be less inclined to ratify the Rome Statute if they know that the judges are ready to rely on “plain meaning” to discard their carefully negotiated agreement with the less-powerful states to not criminalise chemical, biological, or nuclear weapons? To ask the question is to answer it.

I believe that the Rome Statute should criminalise the use of chemical, biological, and nuclear weapons. I’m appalled by the cynical deal the powerful and less-powerful states worked out during the Rome Conference to exempt their preferred WMDs from criminalisation. But treaties are still expressions of state will, which means that states are free to draft profoundly imperfect treaties. And that includes the Rome Statute. To paraphrase the immortal philosopher Donald Rumsfeld: you apply the treaty you have, not the treaty you wish you had.

19 Responses

  1. But we start with the text and the purpose of the treaty, and then we add (31(3)(c)) any other relevant international law for interpretive purposes (including customary international law). In any event, I don’t see why a particular use of a particular chemical or biological weapon cannot fit within some of the provisions in Article 8 even assuming that there is no complete coverage of ALL chemical and biological weapons.

  2. Kevin ,

    Reading the Rome statute, as a whole, implying the right methods of interpretations, leaves no doubt:

    The statute is criminalizing the use of chemical and biological weapons, why is that?? as follows :

    1)Rome statute , 8(2) reads so :

    Article 8

    War crimes

    2. For the purpose of this Statute, “war crimes” means:

    (i) Intentionally directing attacks against the civilian population as such
    or against individual civilians not taking direct part in hostilities;

    (ii) Intentionally directing attacks against civilian objects, that is, objects
    which are not military objectives;

    (v) Attacking or bombarding, by whatever means, towns, villages,
    dwellings or buildings which are undefended and which are not
    military objectives;

    you do understand then , that attacking civilians , not involved , is what the Rome statute and alike , are trying to prevent . When using chemical weapons, you can’t control the outcome of the attack, since, winds, may divert the gas, far from the objects targeted (even if military ones). So , he who does it , is aware of such possible , probable outcome , and typically , can’t be controlled . and read well :

    attacking : ” by whatever means ….” .

    2) Activists or not , has got nothing to do with interpretation of the law . each code or provision , has what is called :

    ” Objective intent ”

    The objective intent, is the ultimate interpretation of the law (provided, that textual interpretation is ambiguous). The objective intent , represents the values , the merits , the ultimate principles and goals , that , reins upon the provisions , and reins upon the whole codes ( like for example : rule of law ) . That is why , you find in every constitution , the provision that :

    No law , shall contradicts the supremacy or the constitution itself .

    The same for the Rome statute, and those ultimate principles, rein over the subjective intent of the lawmaker (states parties in that case).

    3) Finaly , super powers , avoid the rome statute ratification because of obligation to their troops or soldiers mainly , not nuclear weapon . Otherwise, the Americans and Russians for example, wouldn’t take care , so hectically of avoiding proliferation of nuclear weapon in the world.

    Well , one scroll , can’t have it all …..


  3. El Roam,

    You should really familarise yourself with the debates before making arguments that have been made dozens of times before. No one — including me — contests the idea that using a chemical, biological, or nuclear weapon to intentionally attack civilians or in a disproportionate manner is a war crime that can be prosecuted by the ICC. Literally no one. That is not what we are debating. We are debating whether the mere use of such a weapon (ie, in a discriminate and proportionate manner) is itself a war crime. Nothing else.

  4. just for he who wants , to dig deeper into the ” objective intent ” or purpose , here I quote and refer ( professor aharon Barak , in : INTENTION IS ALL THERE IS: A CRITICAL

    Stanley Fish

    ” In Barak’s argument, both the scope and necessity of discretion
    increase as one moves further in time from the moment of the text’s
    production, and therefore (or so he contends) further and further from
    the control of its original author:
    As the text ages, the law by its nature, weakens the control of the
    author over the text he or she [or they] created, and strengthens the
    control of the legal system—which tries to bridge the gap between
    law and society’s changing needs—in the form of objective
    By “objective purpose” Barak means the purpose or intent of the
    legal system at its highest level of abstraction, that is “the values,
    objectives, interests . . . that the text is designed to actualize in a

    here the link to :


  5. Of course, Stanley Fish himself — my mentor as a graduate student at Duke — unequivocally rejects any theory of interpretation that does not recognize the intent of the author as paramount. For him, the idea that words could mean something other than what the author intended them to mean is epistemologically incoherent.

    Here is the money quote from the article for which El Roam provides a link:

    Being focused on intention is not an approach to interpretation — one possible method in competition with other methods — it is interpretation. Absent the presumption that the shapes you have encountered — c, a, t, black marks on a white background — are designed, are purposively produced, there is nothing to be done with them in the way of meaning.

    If interpretation is to be rational and not arbitrary there must be something to be interpreted, something prior to the interpreter’s efforts, something the interpreter is trying to get right, something in relation to which an interpretation can be rejected. What could that something be? There are only two possibilities: the text and the intention of the author. But the text isn’t really a possibility because a text doesn’t become a text — the vehicle of a message – until the assumption of purposive design, of intention, is in place; take that assumption away and the text dissolves into a mass of shapes (remember c, a, t) that mean nothing and, because they mean nothing, can be made to mean anything.

  6. Kevin ,
    Read again what you have written on , and what I have :

    You were writing on the criminalization of the use of such weapon , or opposing it , and I have written that:

    Every use , notwithstanding the results , notwithstanding the use of it , Discriminately or not , is :

    Forbidden according to the Rome statute, read again !!

    I can’t understand you sometimes !!
    Read well : whatever , it is forbidden !! means : the statute , criminalizes it indeed !!

  7. No, you simply do not pay attention to the argument and know nothing about the larger debates of which it is a part.

  8. Kevin ,

    And of course , I refered to professor aharon Barak indeed , and to your student , only as a ” container ” for the content itself . For you do understand, that prof Aharon Barak, has prevailed in his life, more cases, than any other judge I think in the world, cases that vary from: criminal cases, to civil law, to international, military, whatever…..let alone , 18 books , with huge creative and lengthy observations .

  9. just to correct it : your mentor , not student , or whatever …..

  10. KJH – Maybe it would be helpful to know – from your perspective, what *does* 8(2)(b)(xviii) capture? Let’s leave aside chemical weapons uses that are disproportionate (separately criminalized by 8(2)(b)(iv)). No matter what interpretive canons are employed, it presumably is not an ’empty set’.

    Do you contend that the chapeau of 8(2)(b)(xviii) in the statute limits the application of the crime in a fashion not reflected in the Elements of the Crime? Or that the cryptic footnote in the Elements transforms the entire provision into a ‘bookmark’, in case of future IHL consensus concerning chemical weapons use, which will bring to life the provision?

    I sense there a gloss I’m missing in your analysis. Without a great deal of familiarity with the legislative history, my instinct is that the political controversy may have partly related to ‘non-use’ restrictions (production, stockpiling, transfer of chemical weapons). That would seem to have a pretty good nuclear analogue…

  11. Just to accomplish the dish further , one may look to article 51 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), 8 June 1977.”

    Bearing the title of :

    “Protection of the civilian population ” and :

    dictating so :

    ” 5. Among others, the following types of attacks are to be considered as indiscriminate:

    (a) an attack by bombardment by any methods or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects; and

    (b) an attack which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.”

    And understand so , other external source, for prohibition of the use of chemical weapon, with or without an explicit understanding of those ” chemical provisions ” in the Rome statute.


  12. Just correctin my comment above , rather we deal with paragraph 4 , states as follows :

    4. Indiscriminate attacks are prohibited. Indiscriminate attacks are:

    (a) those which are not directed at a specific military objective;

    (b) those which employ a method or means of combat which cannot be directed at a specific military objective; or

    (c) those which employ a method or means of combat the effects of which cannot be limited as required by this Protocol; and consequently, in each such case, are of a nature to strike military objectives and civilians or civilian objects without distinction.


  13. El Roam,

    You do realise, right, that you continue to argue a point that no one — literally no one — disagrees with?

  14. whatever Kevin , I wouldn’t even bother anymore , to quote you , from your post itself quoting …..

  15. Whiting is a Harvard professor, former senior trial attorney at the ICTY and chief of investigations and prosecution coordinator at the ICC. I suspect he knows what he’s talking about.

  16. Ah, the old fallacy of argumentum ad verecundiam. Should’ve expected someone to weigh in with that one!

  17. PS: I will bet you $1000 that Alex does not believe he’s right because he has good credentials.

  18. Dear colleagues,

    I suppose the first question that arises relates to the nature of the armed concflict in Syria between ISIS and the Syrian governmental forces as being the parties to the conflict, i.e. whether it constitutes an international or a non-international armed conflict in view of the invovment of thirsd States.

    If the latter was still the case, the real problem relates to the question whether in case of a SC referral the referral would encompass Art. 8 of the Rome Statut as amended (or rather not). On that issue (what I believe is the real issue to be discussed) see Zimmermann/ Sener, AJIL 2014, p. 436 et seq.


    Provided we assume it has not become internationalized by third States fighign either on tehn side of the giovernemtn or merely fight ISIS

  19. The point is not that Alex would believe he’s right because he has good credentials. It’s the other way around. He has good credentials because he is probably right more often than he’s wrong.

    In any event, there is nothing inappropriate about suggesting that a person’s practical experience and credentials lend credibility to their argument.

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