Indiscriminate weapon
The International Court of Justice (ICJ) has recognized the principle of distinction as one of the two ‘cardinal principles contained in the texts constituting the fabric of humanitarian law.’ICJ, Legality of the threat or use of nuclear weapons, Advisory Opinion of 8 July 1996, §78. As a consequence of the requirement to distinguish at all times between combatants and military objectives on the one hand, and civilians and civilian objects on the other hand, it is prohibited under international humanitarian law (IHL) to launch indiscriminate attacks. Indiscriminate attacks include those ‘which employ a method or means of combat which cannot be directed at a specific military objective’ or ‘the effects of which cannot be limited as required by international humanitarian law’ and which ‘consequently, in each such case, are of a nature to strike military objectives and civilians or civilian objects without distinction’.ICRC Customary IHL study, 2005, Rule 12; Art. 51(4), 1977 Additional Protocol I.
The ICJ has noted that ‘States … must consequently never use weapons that are incapable of distinguishing between civilian and military targets.’ICJ, Legality of the threat or use of nuclear weapons, Advisory Opinion of 8 July 1996, §78. More specifically, it would seem to follow from the prohibition on indiscriminate attacks that weapons that cannot be directed at a specific military objective and weapons whose effects cannot be limited as required under IHL are indiscriminate weapons and are, thus, prohibited.Note that on the basis of the first criterion ('cannot be directed') are considered indiscriminate not only weapons that cannot be directed at all, but also weapons that cannot reliably or accurately be directed at a specific military objective.
However, the rules are silent on how the capacity of a weapon to comply with these requirements is to be assessed. In legal doctrine, a distinction is often proposed between weapons whose use in some circumstances violates the principle of distinction (because of the particular manner of use and contextual factors) and weapons that are ‘inherently’ or 'by their nature' indiscriminate. Only the latter are considered 'indiscriminate weapons' that are illegal 'per se'.According to the ICRC, 'The use of weapons which are by nature indiscriminate is prohibited' under customary international humanitarian law (IHL). ICRC Customary IHL study, 2005, Rule 71. Whereas it is widely recognised that firing rockets blindly into enemy territory or dropping bombs randomly over an area are prohibited methods of warfare, this does not necessarily imply that rockets and bombs are 'indiscriminate weapons' (means of warfare). Because the legal assessment of whether a given weapon can be directed or its effects can be limited as required by IHL is usually treated as context dependent it has proven difficult in practice to agree that specific weapons are illegal per se.Consider the following proposition: 'Thus, for certain types of attack, a dumb bomb, i.e. one fitted with no particular guidance system or sensor mechanism, may be used as the weapon of choice and in absolute compliance with this discrimination rule. An example would be the attack of an isolated military objective where the risk of collateral damage is low. From the weapons law point of view, therefore, a ‘dumb’ bomb is entirely capable of discriminating use and will thus normally comply with the weapons law discrimination requirement. However, rocket systems with no guidance systems and which as a result are incapable of being directed at a particular military objective would breach the discrimination rule.’ W. H. Boothby, Weapons and the Law of Armed Conflict, Oxford University Press, 2009, 227. On the context-dependency of these assessments, see also the Commentary to the HPCR Manual on International Law Applicable to Air and Missile Warfare, 2010, 63-4.
Weapons that are regularly claimed in jurisprudence and legal doctrine to be indiscriminate include
- weapons whose use is the subject of a treaty prohibition (at least in part due to the indiscriminate effects caused by the weapon's use in practice): anti-personnel landmines, balloon-borne bombs, biological weapons, chemical weapons, and cluster munitions;
- and weapons whose use is not currently prohibited by international treaty, such as incendiary weapons, nuclear weapons, mines generally, scud missiles, Katyusha rockets, and V2 rockets.For details and state practice, see ICRC, Customary IHL study, Rule 71 and Practice relating to Rule 71.
Last updated on: 08 August 2017