VI. Legal Standards
International humanitarian law-the laws of war-does not ban white phosphorus munitions either as an "obscurant" to hide military operations or as an incendiary weapon. Its use nonetheless remains regulated by laws-of-war rules on the conduct of hostilities, restrictions that limit the use of all weapons in order to minimize harm to civilians and civilian property. Moreover, particular aspects of white phosphorus munitions-its incendiary effect that causes horrific burns and its wide dispersal when air-burst-raises additional international law concerns.
Human Rights Watch's investigation of Israel's use of white phosphorus munitions during the recent Gaza hostilities determined that, in violation of the laws of war, the IDF generally failed to take all feasible precautions to minimize civilian harm when using white phosphorus, and that, in specific cases, the IDF used white phosphorus in an indiscriminate manner causing civilian death and injury. Individuals who plan, order or conduct indiscriminate attacks willfully-that is, deliberately or recklessly-are responsible for war crimes. The widespread and repeated use of white phosphorus in an unlawful manner-air-burst over densely populated areas when the alternative of non-lethal smoke was available-is indicative of criminal intent.
White Phosphorus Use and the Conduct of Hostilities
The conduct of hostilities in the Gaza Strip is regulated primarily by customary international law, as expressed in the First Additional Protocol of 1977 to the 1949 Geneva Conventions (Protocol I) and the 1907 Hague Regulations. Most of the relevant provisions of both treaties are considered reflective of customary international law, rules of law that are based on established state practice and are binding on all parties to an armed conflict, whether they are states or non-state armed groups, such as Hamas and other Palestinian armed groups.
International humanitarian law places restrictions on the means and methods of warfare by parties to an armed conflict and requires them to respect and protect civilians and captured combatants. The fundamental tenets of this law are "civilian immunity" and "distinction," While humanitarian law recognizes that some civilian casualties are inevitable, it imposes a duty on warring parties at all times to distinguish between combatants and civilians, and to target only combatants and other military objectives. Deliberate attacks against civilians are prohibited. Civilians lose their immunity from attack when and only for such time that they are directly participating in hostilities.
International humanitarian law also protects civilian objects, which are defined as anything not considered a military objective. Prohibited are direct attacks against civilian objects, such as homes, apartments, places of worship, schools, and hospitals-unless they are being used for military purposes. Should a hospital be used for military purposes, it may still only be attacked after a warning with a reasonable time-limit has been issued and gone unheeded.
The laws of war prohibit indiscriminate attacks. Indiscriminate attacks are of a nature to strike military objectives and civilians or civilian objects without distinction. Examples of indiscriminate attacks are those that are not directed at a specific military objective or that use weapons that cannot be directed at a specific military objective. Thus, if a party launches an attack without attempting to aim properly at a military target, or in such a way as to hit civilians without regard to the likely extent of death or injury, it would amount to an indiscriminate attack. Prohibited indiscriminate attacks also include area bombardment, which are attacks by artillery or other means that treat as a single military objective a number of clearly separated and distinct military objectives located in an area containing a concentration of civilians and civilian objects.
Also prohibited are attacks that violate the principle of proportionality. Disproportionate attacks are those that are expected to cause incidental loss of civilian life or damage to civilian objects that would be excessive in relation to the concrete and direct military advantage anticipated from the attack.
Humanitarian law requires that the parties to a conflict take constant care during military operations to spare the civilian population and to "take all feasible precautions" to avoid or minimize the incidental loss of civilian life and damage to civilian objects. These precautions include doing everything feasible to verify that the objects of attack are military objectives and not civilians or civilian objects, and giving "effective advance warning" of attacks when circumstances permit.
International humanitarian law does not prohibit fighting in urban areas, although the presence of civilians places greater obligations on warring parties to take steps to minimize harm to civilians. Forces deployed in populated areas must avoid locating military objectives near densely populated areas, and endeavor to remove civilians from the vicinity of military objectives. Belligerents are prohibited from using civilians to shield military objectives or operations from attack. "Shielding" refers to purposefully using the presence of civilians to render military forces or areas immune from attack. However, even if one party considers opposing forces responsible for having located legitimate military targets within or near populated areas, it is not relieved from the obligation to take into account the risk to civilians when conducting attacks.
White Phosphorus and Law on Incendiary Weapons
Protocol III to the Convention on Conventional Weapons (CCW) regulates the use of incendiary weapons. The protocol defines incendiary weapons as "any weapon or munition which is primarily designed to set fire to objects or to cause burn injury to persons through the action of flame, heat, or combination thereof, produced by a chemical reaction of a substance delivered on the target." White phosphorus is an incendiary weapon.
The primary innovation of Protocol III is to prohibit the use of air-delivered incendiary weapons against military objectives located within a concentration of civilians. Customary laws of war also prohibit the anti-personnel use of incendiary weapons so long as weapons less likely to cause unnecessary suffering are available.
Israel is a party to the CCW but not Protocol III. However, a 1998 Israeli military manual states:
Incendiary arms are not banned…. Nevertheless, because of their wide range of cover, this protocol of the CCW is meant to protect civilians and forbids making a population center a target for an incendiary weapon attack. Furthermore, it is forbidden to attack a military objective situated within a population center employing incendiary weapons. The protocol does not ban the use of these arms during combat (for instance, in flushing out bunkers).
Human Rights Watch opposes any use of incendiary weapons that would result in unnecessary suffering.
Israel 's Use of White Phosphorus under International Law
Israel's use of white phosphorus munitions during the armed conflict in Gaza violated international humanitarian law in two distinct ways. First, the IDF's general use of air-burst white phosphorus as an apparent obscurant in densely populated areas of Gaza violated the obligation to take all feasible precautions to minimize harm to civilians and to civilian objects. Second, the IDF's use of air-burst white phosphorus in specific incidents causing civilian casualties violated the prohibition against indiscriminate or disproportionate attacks.
The use of white phosphorus as an obscurant in densely populated areas of Gaza violated the requirement under international humanitarian law to take all feasible precautions to avoid civilian injury and loss of life. This concern is amplified given the method of use observed by Human Rights Watch and evidenced in media photographs of air-bursting white phosphorus projectiles. Air-bursting spreads burning wedges in a radius up to 125 meters from the blast point, thereby exposing more civilians and civilian objects to potential harm than a localized ground burst.
In incidents investigated by Human Rights Watch, Israeli forces used white phosphorus munitions in an indiscriminate or disproportionate manner in violations of the laws of war. In these incidents, even if the intended use of the white phosphorus was as an obscurant, it had the effect on the ground as a weapon. The rationale for an obscurant seems doubtful because there were either no Israeli forces in the vicinity to screen or such forces were for a considerable period in a stationary deployment. And if the purpose was to obscure military maneuvers, the IDF could have achieved similar obscuring effects through use of smoke artillery without causing the same degree of civilian harm. Israel has not asserted that it used white phosphorus as a weapon, but the apparent absence of nearby Hamas fighters in cases investigated by Human Rights Watch, as well as the legal limitations placed on the use of white phosphorus weapons in populated areas, would not justify its use in this manner. That would remain true even if Hamas forces were deployed among civilians or using civilians as "shields," as Israel has asserted, because Israel would still have a duty to attack Hamas in a more discriminate way so as to minimize civilian casualties.
In the cases investigated, Israeli forces fired air-burst white phosphorus munitions from 155mm artillery. Human Rights Watch has long criticized the IDF's use of high explosive M107 shells in densely populated areas as being indiscriminate. During the recent fighting in Gaza, as in the past, the IDF fired an Israeli modified version of the US M109A3 howitzer called the Doher. It is normally fired as an indirect fire weapon, that is, out of the line of sight. M107 shells have an expected casualty radius between 100 and 300 meters. Air-burst white phosphorus munitions are similarly indiscriminate in their wide dispersal-an area between 63 and 125 meters in radius, depending on the altitude of the burst. The fact that white phosphorus is not as lethal as high explosive M107 shells is irrelevant to the question of whether or not they are being used in an indiscriminate manner in violation of the laws of war.
The IDF's use of white phosphorus munitions may also have violated the prohibition on attacks that are expected to cause civilian harm which is excessive compared to the expected military gain. In cases investigated by Human Rights Watch, the military value of white phosphorus fired as an apparent obscurant appeared to be minimal given the absence of Israeli forces in the vicinity. By comparison, the expected harm to civilians and civilian objects by using white phosphorus was often high, and thus disproportionate in violation of the laws of war. As the incendiary effects of white phosphorus on civilians are well known, the civilian harm caused by white phosphorus use in populated areas was foreseeable.
White Phosphorus Use in Populated Areas and Individual Criminal Responsibility
Serious violations of international humanitarian law committed willfully, that is deliberately or recklessly, are war crimes, and give rise to individual criminal responsibility. War crimes include intentional or indiscriminate attacks on civilians, as well as attacks in which the expected civilian loss is disproportionate compared to the anticipated military gain. Individuals may also be held criminally liable for attempting to commit a war crime, as well as assisting in, facilitating, and aiding or abetting a war crime. Responsibility may also fall on persons planning or instigating the commission of a war crime. Commanders and civilian leaders may be prosecuted for war crimes as a matter of command responsibility when they knew or should have known about the commission of war crimes and took insufficient measures to prevent them or punish those responsible.
Even if intended as an obscurant rather than as a weapon, the IDF's firing of air-burst white phosphorus shells from 155mm artillery into densely populated areas was indiscriminate or disproportionate, and indicates the commission of war crimes.
The IDF's deliberate or reckless use of white phosphorus munitions is evidenced in five ways. First, to Human Rights Watch's knowledge, the IDF never used its white phosphorus munitions in Gaza before, despite numerous incursions with personnel and armor. Second, the repeated use of air-burst white phosphorus in populated areas until the last days of the operation reveals a pattern or policy of conduct rather than incidental or accidental usage. Third, the IDF was well aware of the effects white phosphorus has and the dangers it can pose to civilians. Fourth, if the IDF used white phosphorus as an obscurant, it failed to use available alternatives, namely smoke munitions, which would have held similar tactical advantages without endangering the civilian population. Fifth, in at least one of the cases documented in this report – the January 15 strike on the UNRWA compound in Gaza City – the IDF kept firing white phosphorus despite repeated warnings from UN personnel about the danger to civilians. Under international humanitarian law, these circumstances demand the independent investigation of the use of white phosphorus and, if warranted, the prosecution of all those responsible for war crimes.
 See generally, Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts (Protocol I), 1125 U.N.T.S. 3, entered into force Dec. 7, 1978; Hague Convention IV - Laws and Customs of War on Land: 18 October 1907, 36 Stat. 2277, 1 Bevans 631, 205 Consol. T.S. 277, 3 Martens Nouveau Recueil (ser. 3) 461, entered into force Jan. 26, 1910.JT
See Protocol I, arts. 48, 51(2), and 52(2).
Article 48 of Protocol I states, "Parties to the conflict shall at all times distinguish between the civilian population and combatants and between civilian objects and military objectives and accordingly shall direct their operations only against military objectives."
 Protocol I, art. 51(3).
 Ibid., article 52(1). Military objectives are combatants and those objects that "by their nature, location, purpose or use make an effective contribution to military action and whose total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage." Ibid., art. 52(2).
 Protocol I, art. 52(2).
 Fourth Geneva Convention, art. 19; Protocol I, art. 13(1).
 Articles 51(4) and 51(5) of Protocol I enumerate five kinds of indiscriminate attacks: those that 1) are not directed at a "specific military objective," 2) cannot be directed at "a specific military objective," 3) have effects that violate the Protocol, 4) treat separate urban military objectives as one (carpet bombing), or 5) violate the principle of proportionality.
Ibid., art. 51(5)(b). The expected danger to the civilian population and civilian objects depends on various factors, including their location (possibly within or near a military objective), the accuracy of the weapons used (depending on the trajectory, the range, environmental factors, the ammunition used, etc.), and the technical skill of the combatants (which can lead to random launching of weapons when combatants lack the ability to aim effectively at the intended target). ICRC, Commentary on the Additional Protocols, p. 684.
Protocol I, art. 57. The ICRC Commentary to Protocol I states that the requirement to take "all feasible precautions" means, among other things, that the person launching an attack is required to take the steps needed to identify the target as a legitimate military objective "in good time to spare the population as far as possible." ICRC, Commentary on the Additional Protocols, p. 682.
If there are doubts about whether a potential target is of a civilian or military character, it "shall be presumed" to be civilian. Protocol I, art. 52(3). The warring parties must do everything feasible to cancel or suspend an attack if it becomes apparent that the target is not a military objective. Ibid., art. 57(2).
Ibid., art. 57(2).
Ibid., art. 58(b).
Ibid., art. 58(a).
Ibid., art. 51(7).
Protocol on Prohibitions or Restrictions on the Use of Incendiary Weapons (Protocol III to the CCW), 1342 U.N.T.S. 171, 19 I.L.M. 1534, entered into force Dec. 2, 1983.
 Protocol III to the CCW, art. 1(1).
 Protocol III does not include munitions that "may have incidental incendiary effects," such as smoke artillery.
 Protocol III to the CCW, art. 2(2).
See International Committee of the Red Cross (ICRC), Customary International Humanitarian Law (Cambridge: Cambridge University Press, 2005), rule 85.
 Israel, Military Advocate General Headquarter, Laws of War in the Battlefield, 1998, p. 23.
 Various armed forces prohibit the use of incendiary weapons where it would cause unnecessary suffering. See US Army, Field Manual 27-10 (1956) (the use of incendiary weapons "is not a violation of international law. They should not, however, be employed in such a way as to cause unnecessary suffering to individuals") sec. 36; UK Ministry of Defence, The Manual of the Law of Armed Conflict (Oxford: Oxford University Press, 2004) (white phosphorus "should not be used directly against personnel"), p. 112.
 "Indiscriminate Fire: Palestinian Rocket Attacks on Israel and Israeli Artillery Shelling in the Gaza Strip," Human Rights Watch report, June 30, 2007.
 The expected casualty radius is the radius in which people are likely to be injured by a weapon. The IDF has not to Human Rights Watch's knowledge published its figures for 155mm artillery shells, but press reports give the numbers listed in the text. (Peter Beaumont, "How Israel Put Gaza Civilians in Firing Line," The Guardian, November 12, 2006 and "Gaza's Kids Collect a Different Sort of Shell," Agence France-Presse, May 29, 2006.)
See ICRC, Customary International Humanitarian Law, pp. 568-74.