The Encyclopedia is a project of the Geneva Academy of International Humanitarian Law and Human Rights launched on 2 December 2013. The Enyclopedia aims to provide accurate, up-to-date information on weapons, the effects of their use, and their regulation under public international law, in a format that is accessible to non-specialists.+ Find out more
Additional Protocol I to the 1949 Geneva Conventions, Relating to the Protection of Victims of International Armed Conflicts was adopted on 8 June 1977 and entered into force on 7 December 1978. The Protocol does not contain a single formal prohibition concerning a specific weapon, but it contains provisions that explicitly regulate the use of weapons, sets out an obligation to review the legality of ‘new weapons, means or methods of warfare’ and reaffirms basic rules on the conduct of hostilities that have implications for the legality of the use of weapons. As of June 2015, 174 states were parties to the Protocol, and two were signatories.
Against the backdrop of the war in Vietnam, there was growing support towards the end of the 1960s, for efforts aimed at reaffirming and further developing the rules of international law applicable in armed conflicts, including those governing the conduct of hostilities, from a humanitarian perspective. With the exception of the 1925 Geneva Gas Protocol, rules on the conduct of hostilities were last codified at the 1907 Hague Conference ‘at a time, when bombing did not yet exist’.Reaffirmation and Development of the Laws and Customs Applicable in Armed Conflicts, Report submitted by the ICRC, XXlst International Conference of the Red Cross, Istanbul, 1969, 6. In preparation of the XXlst International Conference of the Red Cross, which took place in Istanbul in 1969, the International Committee of the Red Cross (ICRC) invited experts to discuss, inter alia, the ‘[p]rohibition of "non-directed" weapons or weapons causing unnecessary suffering’. The ICRC report on these discussions noted that ‘[s]ome means of war, owing to the indiscriminate nature of their effects or their imprecision, strike those who should be left outside the fighting’ and that ‘[o]ther weapons, although precise, have appeared to entail unnecessary suffering’. The report reiterated two great principles that govern the use of weapons: first, the right of belligerents to adopt means of injuring the enemy is not unlimited; second, the employment of arms, projectiles or material calculated to cause unnecessary suffering is prohibited. In this connection, the ICRC raised particular concerns about nuclear weapons, bacteriological and chemical weapons and napalm.Reaffirmation and Development of the Laws and Customs Applicable in Armed Conflicts, Report submitted by the ICRC, XXlst International Conference of the Red Cross, Istanbul, 1969, 6, 47-8.These expert discussions were held in February 1969. Annexed to the report were the Draft Rules for the Limitation of Dangers incurred by the Civilian Population in Time of War prepared by the ICRC in 1956 (Annex XIV). Article 14 of the Draft Rules provides: 'Without prejudice to the present or future prohibition of certain specific weapons, the use is prohibited of weapons whose harmful effects - resulting in particular from the dissemination of incendiary, chemical, bacteriological, radioactive or other agents - could spread to an unforeseen degree or escape, either in space or in time, from the control of those who employ them, thus endangering the civilian population. This prohibition also applies to delayed-action weapons, the dangerous effects of which are liable to be felt by the civilian population’. Resolution (XIII) adopted by the Conference, requested the ICRC to hold expert consultations and to submit concrete proposals for rules that would supplement existing law.
Acting on this mandate, the ICRC convened a Conference of Government Experts on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts that met in Geneva between 24 May and 12 June 1971. In connection with measures aimed at strengthening the protection of civilian populations against dangers of hostilities, these experts discussed concerns raised by 'blind' weapons or those causing unnecessary suffering.Conference of Government Experts on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts Geneva, 24 May - 12 June 1971, Report submitted by the ICRC, ICRC, 1971, 19. The question was raised whether 'a catalogue of weapons of which the use should be strictly forbidden or limited could not be drawn up’, but experts could not agree whether all weapons, including weapons of mass destruction, or only weapons that were not the subject of discussion in other international fora should be studied further (e.g. incendiary weapons, 'anti-personnel and delayed-action bombs').Conference of Government Experts on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts (Geneva, 24 May - 12 June 1971), Report on the Work of the Conference, ICRC, 1971, 22, 84.
At the second session of the Conference of Government Experts, in 1972, the ICRC was asked to consult legal, military and medical experts on the use of certain conventional weapons that may cause unnecessary suffering or have indiscriminate effects.Conference of Government Experts on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts (Second session, Geneva, 3 May – 3 June 1972), Report on the Work of the Conference, Vol. 1, ICRC, 1972, 203. The working group of experts that was set up pursuant to this mandate met twice in 1973 and later that year issued a report entitled Weapons that May Cause Unnecessary Suffering or Have Indiscriminate Effects, describing in detail the effects on the human body of ‘major categories of weapon’, including small-calibre single projectiles, such as those fired by rifles or machine-guns, explosive weapons of the blast and fragmentation types, time-delay weapons, such as mines and booby-traps, incendiary weapons, as well as certain laser weapons.Weapons that May Cause Unnecessary Suffering or Have Indiscriminate Effects, Report on the Work of Experts, ICRC, 1973.
To ‘study in depth, from the humanitarian standpoint, the question of the prohibition or limitation of the use of conventional weapons that may cause unnecessary suffering or have indiscriminate effects’, the ICRC convened, in two sessions, the Conference of Government Experts on the Use of Certain Conventional Weapons (Lucerne, 1974 and Lugano, 1976). The Lucerne conference focused on incendiary weapons, small-calibre projectiles, blast and fragmentation weapons, delayed-action and treacherous weapons, as well as some new weapons. It also discussed proposed criteria for determining the legality of weapons, mainly ‘unnecessary suffering (or superfluous injury), indiscriminateness, and treacherous (or perfidious) character’ of a weapon.Conference of Government Experts on the Use of Certain Conventional Weapons (Lucerne, 24.9-18.10.1974), Report, ICRC, 1975, §18; See also, Conference of Government Experts on the Use of Certain Conventional Weapons (Second Session - Lugano, 28.1.-26.2.1976), Report, ICRC, 1976.
These expert discussions, together with work undertaken at and by the United Nations, supported and informed the parallel diplomatic process, which eventually led to the adoption of Protocol I additional to the 1949 Geneva Conventions. In 1973, a report prepared by the UN Secretary-General on existing rules of international law concerning the prohibition or restriction of use of specific weapons proposed three general criteria for identifying the (il-)legality of weapons: unnecessary suffering or superfluous injury, indiscriminate effects, and whether the weapon kills treacherously.UN doc. A/9215, 1973 (2 vols.) The report demonstrated, in the words of one observer,
that the generic rules are very difficult to apply to particular weapons and that the specific rules do not cope with the weapons that are the most likely to do harm to the civilian population or to cause injury and suffering out of proportion to the military advantage to be gained from the use of such weapons. The law was, to put the matter bluntly, an ineffective instrument for establishing some control over the use of weapons, even if a good-faith effort were made to apply it’.R. Baxter, ‘Conventional Weapons’, in M. N. Schmitt and W. Heintschel von Heinegg (eds), The Conduct of Hostilities in International Humanitarian Law, Vol. II, Ashgate, 2012, 56. See Resolution XXIII adopted by the International Conference on Human Rights (Teheran, 1968) and subsequent resolutions on human rights in armed conflicts; General Assembly resolution 3076 (XXVI) and other resolutions on incendiary weapons; the UN Secretary-General’s report on Respect for Human Rights in Armed Conflicts: Existing Rules of International Law concerning the Prohibition or Restriction of Use of Specific Weapons: Survey prepared by the Secretariat, UN doc. A/9215, 1973; and the UN Secretary-General’s report on Napalm and Other Incendiary Weapons and All Aspects of Their Possible Use, UN doc. A/8803/Rev. 1, 1973.
The Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts (CDDH), convened by Switzerland, met four times in Geneva between 1974 and 1977.From 20 February to 29 March 1974, from 3 February to 18 April 1975, from 21 April to 11 June 1976 and from 17 March to 10 June 1977. The Official Records of the Diplomatic Conference can be accessed online (Library of Congress). The CDDH established an ‘Ad Hoc Committee of the whole on Conventional Weapons’ to ‘consider the question of the prohibition or restriction of the use of conventional weapons likely to cause unnecessary suffering or to produce indiscriminate effects’.Summary Records of the Ad Hoc Committee on Conventional Weapons, Official Records of the Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts (Geneva, 1974 – 1977), Vol. XVI, [Swiss] Federal Political Department, Bern, 1978. Ultimately, the Diplomatic Conference did not reach agreement on weapon specific restrictions or prohibitions. Several delegations were strongly opposed to discussing weapons of mass destruction, which were excluded from the mandate of the Ad hoc Committee.The ICRC had not included in its drafts of the additional protocols ‘any rules governing atomic, bacteriological and chemical weapons’, on the basis that these were either the subject of international agreements or of ongoing discussions within intergovernmental organizations. (Introduction to the Commentary, Draft Additional Protocols to the Geneva Conventions of August 12, 1949, ICRC, Geneva, 1973.) And whilst some delegations were in favour of drawing up prohibitions on certain conventional weapons, other delegations argued that such prohibitions fell within the ambit of UN disarmament fora, rather than the CDDH. According to these delegations, the CDDH should limit itself to elaborating criteria, based on established legal principles, to assist other bodies in elaborating restrictions or prohibitions on specific weapons.See, e.g. the Statement by Mr. Gribanov (USSR), in Summary Records of the Ad Hoc Committee on Conventional Weapons, Official Records of the Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts (Geneva, 1974 – 1977), Vol. XVI, p. 186, [Swiss] Federal Political Department, Bern, 1978. See also, M. Bothe et al., New Rules for Victims of Armed Conflicts: Commentary on the Two 1977 Protocols Additional to the Geneva Conventions of 1949, 2nd edn., M. Nijhoff, Leiden, Boston, 2013, 217-21; R. Baxter, ‘Humanitarian Law and Humanitarian Politics? The 1974 Diplomatic Conference on Humanitarian Law’, in (vol. 16) Harvard International Law Journal (1975) 1; F. Kalshoven, ‘Conventional Weapons in the "Reaffirmation and Development" of the 1970s’, in Arms, Armaments and International Law, Collected Courses of the Hague Academy of International Law, vol. 191, 1985, 225-51.
In spite of these disagreements, in a resolution (Resolution 22 (IV)) on the ‘Follow-up regarding conventional weapons prohibition or restriction of use of certain weapons’ the CDDH expressed its conviction that
the suffering of the civilian population and combatants could be significantly reduced if agreements can be attained on the prohibition or restriction for humanitarian reasons of the use of specific conventional weapons, including any which may be deemed to be excessively injurious or to have indiscriminate effects.
According to that resolution, agreement existed on the desirability of prohibiting the use of conventional weapons, the primary effect of which is to injure by fragments not detectable by X-ray. Further, there was ‘a wide area of agreement with regard to land-mines and booby-traps’. However, there were still ‘divergent views on the desirability of prohibiting or restricting the use of incendiary weapons, including napalm’, and consideration of the possibility of prohibiting or restricting the use of ‘other conventional weapons, such as small calibre projectiles and certain blast and fragmentation weapons’ had only just begun.
Recognizing the importance of continuing this work ‘with the urgency required by evident humanitarian considerations’, the CDDH recommended that
a Conference of Governments should be convened not later than 1979 with a view to reaching … agreements on prohibitions or restrictions on the use of specific conventional weapons including those which may be deemed to be excessively injurious or have indiscriminate effects, taking into account humanitarian and military considerations; and …agreement on a mechanism for the review of any such agreements and for the consideration of proposals for further such agreements.
This Conference was eventually convened in 1979 and adopted the Convention on Certain Conventional Weapons (CCW) in 1980.
Additional Protocol I to the Geneva Conventions applies in situations of international armed conflict, including wars of national liberation (Art. 1(4)) and situations of occupation (Art. 1(3)).
Already at the time of its adoption, the Protocol, in many respects, codified customary international law, although some of its provisions represented progressive developments of international humanitarian law (IHL). Today, the vast majority of the Protocol’s provisions are widely considered to reflect customary IHL, including the Protocol’s provisions on the use of weapons, means or methods of warfare (rules governing the conduct of hostilities) and the weapon-specific provisions of Article 35. However, the ICRC, in its Study on Customary IHL (2005) did not find that the Protocol’s provision on ‘New weapons’ (Art. 36) had attained the status of customary law in 2005. (For more details, see below.)
The Protocol, a priori, applies to the use of all weapons in connection with the conduct of hostilities. However, a small number of states have made reservations as to the applicability of the Protocol’s ‘new’ rules (those that were not part of customary IHL in 1977) to nuclear weapons.Which rules of the Protocol were 'new' in 1977 is an open question. The United States of America believe, for instance, that 'the provisions on reprisals and the protection of the environment are new rules that have not been incorporated into custornary law'. (International Court of Justice, Legality of the Threat or Use of Nuclear Weapons, Written Statement of the Government of the United States of America, 20 June 1995, 25.) One scholar has argued that whereas the prohibition on indiscriminate attacks in Art. 51(4) of the Protocol was a reaffirmation of a customary rule, the prohibition on indiscriminate weapons (i.e. means of combat which cannot be directed at a specific military objective or whose effects cannot be limited as required by the Protocol) in Art. 51(4)(b) and (c) is a development of the law, - a 'new rule' introduced by the Protocol. (W. Boothby, The Law of Targeting, 2012, 260.) Canada, France and the United Kingdom affirm that the rules introduced by Protocol I were intended to apply exclusively to ‘conventional weapons’, and do not have any effect on, regulate or prohibit the use of nuclear weapons.Canada, for example, made the following reservation at the time of ratification: 'It is the understanding of the Government of Canada that the rules introduced by Protocol I were intended to apply exclusively to conventional weapons. In particular, the rules so introduced do not have any effect on and do not regulate or prohibit the use of nuclear weapons.' See also the reservation by the United Kingdom. The French reservation is even more far-reaching in that it is not limited to the 'new' rules, i.e. those 'introduced' by the Protocol: 'Le Gouvernement de la République française continue de considérer que les dispositions du protocole concernent exclusivement les armes classiques, et qu'elles ne sauraient ni réglementer ni interdire le recours à l'arme nucléaire, ni porter préjudice aux autres règles du droit international applicables a d'autres activités, nécessaires à l'exercice par la France de son droit naturel de légitime défense.' Other nuclear-armed states are either not parties to the Protocol, e.g. the United States of America, or have not made such a reservation, e.g. Russia or China. However, some of these states have argued elsewhere that 'the new rules contained in the Protocol were not intended to apply to nuclear weapons'. (International Court of Justice, Legality of the Threat or Use of Nuclear Weapons, Written Statement of the Government of the United States of America, 20 June 1995, 25.) See also, International Court of Justice, Legality of the Threat or Use of Nuclear Weapons, Written Statement and Comments of the Russian Federation on the Issue of the Legality of the Threat or Use of Nuclear Weapons, 16 June 1995. Importantly, though, even if certain rules of the Protocol are not applicable as treaty-based rules to nuclear weapons, customary rules reaffirmed in the Protocol’s provisions are. The International Court of Justice (ICJ) found in its Advisory Opinion of 8 July 1996 on the Legality of the Threat or Use of Nuclear Weapons that humanitarian law applies to nuclear weapons (§§85, 86) and that ‘[t]he fact that certain types of weapons were not specifically dealt with by the 1974-1977 Conference does not permit the drawing of any legal conclusions relating to the substantive issues which the use of such weapons would raise’.See the declarations made by Ireland and the Holy See to this effect. For a discussion of reservations to the Protocol, see J. Gaudreau, ‘The reservations to the Protocols Additional to the Geneva Conventions for the Protection of War Victims’, (no. 849) International Review of the Red Cross (2003) 143-84.
Article 35 sets out basic rules on methods and means of warfare, codifying principles articulated previously, including in the 1868 St. Petersburg Declaration and in the Hague Regulations annexed to 1899/1907 Hague Convention IV.
Article 35(1) restates the fundamental principle that
[ I ]n any armed conflict, the right of the Parties to the conflict to choose methods or means of warfare is not unlimited.
Although the ICRC did not make it into a separate ‘Rule’ in its Customary IHL Study, this rule is generally considered to be of customary nature, applicable in non-international and international armed conflicts. Its scope and interpretation remains somewhat unclear, however.
According to one commentary on Protocol I, the principle refers to limitations on the choice of methods and means of warfare stemming from rules that specifically prohibit or restrict the use of particular weapons (e.g. poison or poisoned weapons), as well as limitations ‘inherent in the complementary principles of necessity and humanity which underlie the law governing the conduct of hostilities’.M. Bothe et al., New rules for victims of armed conflicts, Commentary on the two 1977 Protocols additional to the Geneva Conventions of 1949, Martinus Nijhoff Publishers, The Hague/Boston/London, 1982, 224. Another commentary stresses that the rule places legal limitations on the use of weapons in war that cannot be set aside by reference to a state of necessity, Kriegsräson or military necessity (except when explicitly provided for by IHL). With regard to the latter, the commentary states:
Any violence which exceeds the minimum that is necessary is unlawful and it is on this principle that all law relating to the conduct of hostilities is ultimately founded. This principle is expressed in specific rules in the Protocol, but it does not govern only these specific rules. Its scope also extends to situations which are not covered by these rules. This is a direct consequence of the principle which states that the Parties to the conflict do not have an unlimited right.The commentary also highlights the role of this rule as a limit on the weapons chosen for the purposes of reprisals, and points to the connection between this rule and the Martens Clause. (Y. Sandoz et al. (eds), Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949, ICRC/Martinus Nijhoff, Geneva, 1987, §§1382-1409.)
Article 35(2) reaffirms the prohibition on the use of ‘weapons, projectiles and material and methods of warfare of a nature to cause superfluous injury or unnecessary suffering’. The general principle prohibiting the use of weapons that cause superfluous injury or unnecessary suffering is set forth in a number of treaties, including the 1868 St. Petersburg Declaration and the 1907 Hague Regulations. This prohibition is widely considered to be part of customary IHL, applicable in international and non-international armed conflicts.ICRC, Customary IHL study, 2005, Rule 70.
According to the ICRC, among the weapons that have been cited in practice as causing unnecessary suffering if used in certain or all contexts are lances or spears with a barbed head, serrated-edged bayonets, expanding bullets, explosive bullets, poison and poisoned weapons, including projectiles smeared with substances that inflame wounds, biological and chemical weapons, weapons that primarily injure by fragments not detectable by X-ray, including projectiles filled with broken glass, certain booby-traps, anti-personnel landmines, torpedoes without self-destruction mechanisms, incendiary weapons, blinding laser weapons, and nuclear weapons. In 2005, the ICRC found that ‘There is insufficient consensus concerning all of these examples to conclude that, under customary international law, they all violate the rule prohibiting unnecessary suffering. However, there is agreement that some of them are prohibited’.ICRC Customary IHL study, 2005, Rule 70.
Article 35(3) prohibits the use of ‘methods or means of warfare which are intended, or may be expected, to cause widespread, long-term and severe damage to the natural environment’.
The provision reflects growing realization in the 1970s that weapon effects endure, often long after a conflict has ended. The ICRC commentary (1987) on this provision highlights in particular the negative long-term effects of explosive remnants of war (ERW) and toxic remnants of war (TRW): ‘all delayed-action devices or those which have not exploded, for whatever reason, have a similar effect on the environment, with ominous consequences. In addition, chemical components of certain material war remnants can have permanent harmful effects on humans, animals, vegetation, water, land and the ecosystem as a whole’.Y. Sandoz et al. (eds), Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949, ICRC/Martinus Nijhoff, Geneva, 1987, §1443. According to one scholar, this ‘ecological principle’ was suggested at the Lucerne conference, and represents ‘the single outstanding innovation in an otherwise classical list’.F. Kalshoven, ‘Conventional weapons in the "reaffirmation and development" of the 1970s’, in Arms, Armaments and International Law, Collected Courses of the Hague Academy of International Law, vol. 191, 1985, 244.
According to the ICRC, it is a rule of customary IHL, applicable in international and non-international armed conflicts, that ‘[t]he use of methods or means of warfare that are intended, or may be expected, to cause widespread, long-term and severe damage to the natural environment is prohibited’ and that the ‘[d]estruction of the natural environment may not be used as a weapon’.ICRC, Customary IHL Study, 2005, Rule 45. Whereas this prohibition sets an absolute prohibition on damage to the natural environment (irrespective of harm caused to people), whose violation can never be justified on the basis of military necessity, the threshold is extremely high due to the cumulative requirement of ‘widespread, long-term and severe’ damage. In practice, therefore, it remains unclear what weapons would be captured by this prohibition. According to the ICRC, herbicides can be prohibited on this basis, and, in the view of many, nuclear weapons can as well.ICRC, Customary IHL Study, 2005, Rule 76. Note that certain nuclear-armed states may not be bound by this rule as far as nuclear weapons are concerned if, and to the extent that the doctrine of 'persistent objector' exists and is indeed admissible in this context.
In addition to provisions explicitly pertaining to weapons (or means of warfare), the Protocol also sets out rules governing the conduct of hostilities, which have implications for the legality of the use of weapons in certain circumstances. Of particular interest in this context is the prohibition on indiscriminate attacks.
Article 51(4) prohibits (among others) attacks that ‘employ a method or means of combat which cannot be directed at a specific military objective’, as well as attacks that ‘employ a method or means of combat the effects of which cannot be limited as required by [the] Protocol’ and ‘consequently, in each such case, are of a nature to strike military objectives and civilians or civilian objects without distinction'.Art. 51(4)(b) and (c).
It is generally accepted that the prohibition of indiscriminate attacks reaffirmed in Art. 51(4) of the Protocol supports and implies the prohibition, under customary international law applicable in both international and non-international armed conflicts, of weapons that are by nature indiscriminate, i.e. those ‘that cannot be directed at a military objective or whose effects cannot be limited as required by international humanitarian law’.ICRC, Customary IHL study, 2005, Rule 71. For Cassese the prohibition on the use of indiscriminate weapons is ‘a natural corollary’ of the general principle of distinction. (A. Cassese, ‘The Prohibition of Indiscriminate Means of Warfare’, in P. Gaeta and S. Zappalà (eds.), The Human Dimension of International Law: Selected Papers of Antonio Cassese, 2008, 173.) Boothby, argues, that although ‘the rule prohibiting indiscriminate attacks was already established as a customary rule’ when the Protocol was adopted, ‘the indiscriminate weapons rule’ (Arts. 51(4)(b) and (c)) was a new rule of international law introduced by the Protocol, to which the reservations in respect of nuclear weapons would, thus, apply. (W. Boothby, The Law of Targeting, 2012, 260.)
Although the existence of the customary rule prohibiting indiscriminate weapons is widely accepted, its scope remains uncertain. In the absence of a weapon-specific treaty, it is unclear which weapons are ‘by nature indiscriminate’. Among the weapons that have been cited in practice as being indiscriminate in certain or all contexts, are chemical weapons, biological weapons, nuclear weapons, poison, incendiary weapons, mines, including anti-personnel landmines, booby-traps, explosives discharged from balloons, V-1 and V-2 rockets, Katyusha rockets, Scud missiles, cluster munitions, and environmental modification techniques.ICRC Customary IHL study, 2005, Rule 71.
Any weapon that is not specifically prohibited, inherently indiscriminate or of a nature to cause superfluous injury or unnecessary suffering, must in its use as a means of warfare still comply with the other rules governing the conduct of hostilities. These include the obligation to take constant care to spare the civilian population, civilians and civilian objects, and to take all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event to minimizing, incidental civilian harm reaffirmed in Art. 57(2)(a)(ii)) of the Protocol, as well as the prohibition on disproportionate attacks reflected in Art. 57(2)(a)(iii). These provisions are widely considered to reflect customary law, applicable in both international and non-international armed conflict.ICRC Customary IHL study, Rules 14, 15, and 17. However, as these rules do not set out weapon-specific requirements it is an open question whether particular weapons can be deemed to be inherently disproportionate or inherently incompatible with precautionary obligations, in certain or all contexts. Whereas some scholars acknowledge debate about the inherent disproportionality of nuclear weapons, white phosphorous, anti-personnel landmines and cluster munitions,S. Casey-Maslen and S. Weill, ‘The Use of Weapons in Armed Conflict’, in S. Casey-Maslen (ed.), Weapons under International Human Rights Law, Cambridge University Press, 2014, 263-8. others contend that the proportionality rule has ‘no direct applicability to the legitimacy of a weapon’.W. Boothby, Weapons and the Law of Armed Conflict, Oxford University Press, 2009, 79. Although it is generally agreed that the requirement to take constant care to spare civilians and to take all feasible precautions do not imply a prohibition of specific weapons, questions about compliance with these rules have arisen, notably, in respect of the use of explosive weapons with wide area effects in populated areas, and in respect of increasingly autonomous weapon systems.See, e.g., M. Brehm, ‘International Humanitarian Law and the Protection of Civilians from the Effects of Explosive Weapons’, in C. Harvey et al. (eds), Contemporary Challenges to the Laws of War: Essays in Honour of Professor Peter Rowe, 2014, 235-67; J. D. Herbach, ‘Into the Caves of Steel: Precaution, Cognition and Robotic Weapon Systems Under the International Law of Armed Conflict’, in 4(3) Amsterdam Law Forum (2012), 3-20.
Article 36 of Additional Protocol I provides:
[ I ]n the study, development, acquisition or adoption of a new weapon, means or method of warfare, a High Contracting Party is under an obligation to determine whether its employment would, in some or all circumstances, be prohibited by this Protocol or by any other rule of international law applicable to the High Contracting Party.
Article 36, thus, requires each state party to the Protocol to determine whether the employment of any new weapon, means or method of warfare that it studies, develops, acquires or adopts would, in some or all circumstances, be prohibited by international law. The provision, thus, leaves open how a legal review is to be carried out, and it does not call for any specific output or measure to be taken as a result of the review.
Whether the wording of Art. 36 reflects customary law today is uncertain, but it is clearly in every states’ interest to review the legality of its weapons. Assessing the legality of a new weapon contributes to ensuring that IHL is applied, and a customary obligation to review new weapons can, arguably, be inferred from the duty to respect and ensure respect for IHL.Although the ICRC did not include a rule on weapons review in its Customary IHL study of 2005, in a document published in 2006, the ICRC argued that ‘[t]he requirement that the legality of all new weapons, means and methods of warfare be systematically assessed is arguably one that applies to all States, regardless of whether or not they are party to Additional Protocol I. I.’ (K. Lawand et al., A Guide to the Legal Review of New Weapons, Means and Methods of Warfare Measures to Implement Article 36 of Additional Protocol I of 1977, ICRC, 2006, 4.) Others contend that ‘Article 36 may be an emerging customary norm’. (S. Casey-Maslen et al., ‘The review of weapons under international humanitarian law and human rights’, in S. Casey-Maslen (ed.), Weapons under International Human Rights Law, Cambridge University Press, 2014, p. 414.) Whether the scope of a possible customary obligation is identical to that of the treaty provision is unclear.(See on this point, W. Boothby, Weapons and the Law of Armed Conflict, Oxford University Press, 2009, 241.) There is, thus, not only a strong link between Art. 36 and the principles laid down in Arts. 35, 54 and 57 of the Protocol (discussed above), but also between Art. 36 and Art. 1(1) and (2) of the Protocol (see below), respectively, their customary counterparts.
Pursuant to Article 1(1) of Additional Protocol I, states parties to the protocol ‘undertake to respect and to ensure respect for [the] Protocol in all circumstances’. The same language is included in all four 1949 Geneva Conventions. These provisions reflect a customary obligation on all states to respect and ensure respect for IHL by their armed forces and other persons or groups acting in fact on their instructions, or under their direction or control.ICRC Customary IHL study, 2005, Rule 139.
There is some debate about the precise scope of the obligation to ‘ensure respect’ for IHL, especially regarding compliance with IHL by others. Arguably, a customary obligation to review the legality of new weapons can be inferred from the duty to respect and ensure respect for IHL. With respect to the arms trade, the argument has been advanced that the obligation to ensure respect for IHL entails that arms transfer decisions must include consideration of whether the recipient is likely to respect IHL.The Arms Trade Treaty, Academy Briefing no. 3, Geneva Academy of International Humanitarian Law and Human Rights, 2013, 15. Both the Agenda for Humanitarian Action adopted in Resolution 1 at the 28th International Conference of the Red Cross and Red Crescent in 2003, and Resolution 3 adopted at the 30th International Conference in 2007 stressed that, ‘in light of the obligation of states to respect and ensure respect for IHL, strict control of the availability of arms and ammunition is required so that they do not end up in the hands of those who may be expected to use them in violation of IHL’.International Humanitarian Law and the challenges of contemporary armed conflicts, Report prepared by the International Committee of the Red Cross, 31st International Conference of the Red Cross and the Red Crscent, 2001, 47. See also C. Waszink, ‘Arms Transfer Criteria Based on International Humanitarian Law and their Practical Application’, in Proceedings of the Bruges Colloquium: Current perspectives on regulating means of warfare, 18-19 October 2007; A. Boivin, ‘Complicity and beyond: International law and the transfer of small arms and light weapons’, in 87(859) International Review of the Red Cross (2005); M. Brehm, ‘The Arms Trade and States' Duty to Ensure Respect for Humanitarian and Human Rights Law’, in 12(3) Journal of Conflict and Security Law (2007). Generally, on the obligation to ensure respect, see B. Kessler, ‘The duty to 'ensure respect under common Article 1 of the Geneva Conventions: its implications on international and non-international armed conflicts’, in (44) German Yearbook of International Law (2001); L. Boisson de Chazournes and L. Condorelli, ‘Common Article 1 of the Geneva Conventions revisited: Protecting collective interests’, in 82(837) International Review of the Red Cross (2000).
Article 1(2) of Additional Protocol I stipulates:
in cases not covered by the law in force, the human person remains under the protection of the principles of humanity and the dictates of the public conscience.
This is a reiteration of the ‘Martens Clause’, which was first included in the preamble to 1899 Hague Convention II on the Laws and Customs of War on Land. The Preamble of Additional Protocol II to the Geneva Conventions contains similar language.
According to the International Court of Justice, the Martens Clause ‘has proved to be an effective means of addressing the rapid evolution of military technology'.Legality of the Threat or Use of Nuclear Weapons, International Court of Justice, Advisory Opinion, 8 July 1996, §78. There is, however, ongoing debate about how exactly the Martens Clause contributes to the regulation of weapons under international law. This question has particularly been debated in connection with blinding laser weapons, nuclear weapons, and autonomous weapons systems, as well as new weapons more generally.See, e.g., P. Asaro, ‘Jus nascendi, Robotic Weapons and the Martens Clause’, in M. R. Calo (eds) Robot Law, forthcoming ; T. D. Evans, ‘At War with the Robots: Autonomous Weapon Systems and the Martens Clause’, 41(697) Hofstra Law Review (2014), available at SSRN. For an introduction to the Martens clause and a bibliography, see V. Koutroulis, ‘Martens Clause’, in Oxford Bibliographies in International Law, last updated 24 July 2013.
Last updated on: 08 August 2017