The conflict in Darfur between the government and rebel forces is considered a non-international (internal) armed conflict under international humanitarian law (the laws of war). Serious violations of international humanitarian law constitute war crimes.117
It is widely recognized that a civilian population suffering undue hardship is entitled to receive humanitarian relief essential to its survival.118 In a report on emergency assistance to southern Sudan in 1996, the U.N. Secretary-General stated:
Any attempt to diminish the capacity of the international community to respond to conditions of suffering and hardship among the civilian population in Sudan can only give rise to the most adamant expressions of concern as a violation of recognized humanitarian principles, most importantly, the right of civilian populations to receive humanitarian assistance in times of war.119
All parties to an internal armed conflict, government forces, government-backed militias and rebel groups alike, must allow and facilitate rapid and unimpeded passage of impartial humanitarian assistance for civilians in need.120 During numerous armed conflicts the U.N. Security Council has called on the parties to provide safe and unimpeded access for humanitarian assistance. The Rome Statute of the International Criminal Court, which is investigating serious international crimes in Darfur, lists the deprivation of access to food and medicine, calculated to bring about the destruction of part of a population as a crime against humanity when committed as part of a widespread or systematic attack against a civilian population.121
Humanitarian relief agencies cannot in practice function without the express or implied consent of the warring factions. International humanitarian law provides that consent cannot be refused on arbitrary grounds.122 According to the Commentary of the International Committee of the Red Cross, if a civilian population is at risk of starvation, a party is obliged to give consent to an impartial humanitarian relief organization.123 And while international humanitarian law permits parties to a conflict to take certain measures to control the content and delivery of humanitarian assistance, they cannot deliberately or willfully impede its delivery.124
Parties to an armed conflict must ensure that humanitarian workers have the freedom of movement to conduct humanitarian operations. Only in the case of imperative military necessity may their movements be restricted; these restrictions must be limited and temporary, such as when relief operations interfere with military operations and could endanger humanitarian workers.125 The U.N. Security Council adopted a resolution in 2000 on the protection of civilians in armed conflicts in which it called upon governments and opposition armed groups to ensure the safety, security and freedom of movement of humanitarian relief workers.126
International humanitarian law provides special protection for humanitarian relief workers, which considers their safety and security an indispensable condition for the delivery of humanitarian aid.127 On numerous occasions the U.N. Security Council has urged parties to internal armed conflicts to respect and protect humanitarian workers.128
Of course, all humanitarian aid workers are entitled to the same protections from direct or indiscriminate attack as are ordinary civilians and from any mistreatment at any time by a party to the conflict.129 Prohibited are efforts to harass, intimidate, or arbitrarily detain them.130 Likewise, objects used in humanitarian relief operations, such as food and medicines, buildings, materials, and vehicles, are civilian objects and must be respected and protected.131 Destruction, theft and looting of such objects is prohibited.132
 International Committee of the Red Cross (ICRC), Customary International Humanitarian Law (Cambridge Univ. Press, 2005), see rule 156 and accompanying text.
 Customary International Humanitarian Law, p. 197, citing Fourth Geneva Convention of 1949, art. 30; Protocol I, article 70(1); and Protocol II, article 18(2). Article 18(2) of Protocol II, applicable in non-international armed conflicts, states: If the civilian population is suffering undue hardship owing to a lack of the supplies essential for its survival, such as food-stuffs and medical supplies, relief actions for the civilian population which are of an exclusively humanitarian and impartial nature and which are conducted without any adverse distinction shall be undertaken subject to the consent of the High Contracting Party concerned. Although Sudan is not a party to Protocol II, many of its provisions are considered reflective of customary international law.
 U.N. Secretary-General, Report on emergency assistance to Sudan (1996) (emphasis added).
 ICRC, Customary International Humanitarian Law, rule 55, discussed at pp. 194-96.
 Rome Statute of the International Criminal Court (1998), art. 7. During an international armed conflict, willfully impeding relief supplies as part of an effort to starve civilians, is also a war crime. Id. art. 8(2)(b)(xxv).
 ICRC, Customary International Humanitarian Law, p. 197, citing Protocol I, article 70(1); Protocol II, article 18(2). Refusal to allow relief could be equivalent to using starvation as a method of combat in violation of article 14 of Protocol II (Protection of objects indispensable to the survival of the civilian population).
 ICRC, Commentary on the Additional Protocols of 1977 to the Geneva Conventions of 1949 (Nijhoff, Geneva: 1987), p. 1479.
 ICRC, Customary International Humanitarian Law, p. 198, citing Protocol I, article 70(3).
 Ibid., rule 56, p. 200 citing Protocol I, article 71(3).
 U.N. Security Council Resolution 1296 (2000).
 Ibid., rule 31, p. 105, citing Protocol I, article 71(2).
 Ibid., rule 31, p. 107, citing U.N. Security Council resolutions.
 See, e.g. common article 3 to the 1949 Geneva Conventions. Sudan is a party to the 1949 Geneva Conventions.
 ICRC, Customary International Humanitarian Law, rule 31, p. 108, citing various UN Security Council resolutions and state practice.
 Ibid., rule 32, p. 109, citing ICC Statute, article 8(2)(e)(iii) (prohibiting [i]ntentionally directing attacks against personnel, installations, material, units or vehicles involved in a humanitarian assistance mission , as long as they are entitled to the protection given to civilians or civilian objects under the international law of armed conflict).
 Ibid., rule 32, p. 111, citing U.N. Security Council resolutions and state practice.