Rule 158. Prosecution of War Crimes
Rule 158. States must investigate war crimes allegedly committed by their nationals or armed forces, or on their territory, and, if appropriate, prosecute the suspects. They must also investigate other war crimes over which they have jurisdiction and, if appropriate, prosecute the suspects.
Summary
State practice establishes this rule as a norm of customary international law applicable in both international and non-international armed conflicts. This rule, read together with Rule 157, means that States must exercise the criminal jurisdiction which their national legislation confers upon their courts, be it limited to territorial and personal jurisdiction, or include universal jurisdiction, which is obligatory for grave breaches.
International and non-international armed conflicts
The Geneva Conventions require States to search for persons alleged to have committed, or ordered to have committed, grave breaches and to try or extradite them.[1]  The obligation to investigate and prosecute persons alleged to have committed crimes under international law is found in a number of treaties that apply to acts committed in both international and non-international armed conflicts.[2]  The preamble to the Statute of the International Criminal Court recalls “the duty of every State to exercise its criminal jurisdiction over those responsible for international crimes”.[3] 
The rule that States must investigate war crimes and prosecute the suspects is set forth in numerous military manuals, with respect to grave breaches, but also more broadly with respect to war crimes in general.[4]  Most States implement the obligation to investigate war crimes and prosecute the suspects by providing jurisdiction for such crimes in their national legislation, and there have been numerous national investigations and prosecutions of suspected war criminals.[5]  It is not possible, however, to determine whether this practice was pursuant to an obligation or merely a right. An obligation to investigate and prosecute is, however, stated explicitly in a variety of other State practice, such as agreements and official statements.[6] 
In addition, the obligation to investigate war crimes and prosecute the suspects has been reaffirmed on several occasions by the UN Security Council in relation to attacks on peacekeeping personnel and in relation to crimes committed in the non-international armed conflicts in Afghanistan, Burundi, Democratic Republic of the Congo, Kosovo and Rwanda.[7]  In 1946, in its first session, the UN General Assembly recommended that all States, including those not members of the United Nations, arrest persons who allegedly committed war crimes in the Second World War and send them back for prosecution to the State where the crimes were committed.[8]  Since then, the UN General Assembly has, on several occasions, stressed the obligation of States to take measures to ensure the investigation of war crimes and crimes against humanity and the punishment of the perpetrators.[9]  With respect to sexual violence in situations of armed conflict, the UN General Assembly has adopted several resolutions without a vote calling upon States to strengthen mechanisms to investigate and punish all those responsible for sexual violence and to bring the perpetrators to justice.[10] 
The UN Commission on Human Rights has adopted a number of resolutions, most of them without a vote, requiring the investigation and prosecution of persons suspected of having committed violations of international humanitarian law in the context of the conflicts in Burundi, Chechnya, Rwanda, Sierra Leone, Sudan and the former Yugoslavia.[11]  In a resolution on impunity adopted without a vote in 2002, the Commission recognized that perpetrators of war crimes should be prosecuted or extradited.[12] 
In relation to crimes committed in non-international armed conflicts, a number of States have issued amnesties for war crimes, but these have often been found to be unlawful by their own courts or by regional courts and were criticized by the international community (see commentary to Rule 159 on the granting of amnesty).[13]  There is, however, sufficient practice, as outlined above, to establish the obligation under customary international law to investigate war crimes allegedly committed in non-international armed conflicts and to prosecute the suspects if appropriate.
Trial by international or mixed tribunals
States may discharge their obligation to investigate war crimes and prosecute the suspects by setting up international or mixed tribunals to that effect, a fact commented upon in military manuals, national case-law and official statements.[14]  This is evidenced in particular by the creation of the International Military Tribunals at Nuremberg and at Tokyo after the Second World War and, more recently, by the establishment by the UN Security Council of the International Criminal Tribunals for the former Yugoslavia and for Rwanda. The Special Court for Sierra Leone and the Extraordinary Chambers in the Courts of Cambodia for the Prosecution of Crimes Committed during the Period of Democratic Kampuchea were established pursuant to an agreement between the United Nations and Sierra Leone and Cambodia respectively. The International Criminal Court is the first international tribunal to be established by an international treaty which bears no relation to war crimes committed in a specific armed conflict. The Statutes of the International Criminal Court, of the International Criminal Tribunal for Rwanda, of the Special Court for Sierra Leone and of the Extraordinary Chambers for Cambodia expressly include within their jurisdiction war crimes committed during non-international armed conflicts.[15] 
Refugee status
It is generally accepted that persons suspected of having committed war crimes are not entitled to refugee status. This is provided for, in particular, in the Convention on the Status of Refugees, and there is State practice to this effect.[16]  In 1994, with respect to Rwanda, the UN Security Council stressed that “persons involved in [serious breaches of international humanitarian law] cannot achieve immunity from prosecution by fleeing the country” and that “the provisions of the Convention relating to the status of refugees do not apply to such persons”.[17]  Exclusion from asylum of suspected war criminals has also been supported by the UN General Assembly in the Declaration on Territorial Asylum and in Resolution 3074 (XXVIII) on principles of international cooperation in the detection, arrest, extradition and punishment of war criminals.[18] 

[1] First Geneva Convention, Article 49; Second Geneva Convention, Article 50; Third Geneva Convention, Article 129; Fourth Geneva Convention, Article 146.
[2] Genocide Convention, Article VI; Hague Convention for the Protection of Cultural Property, Article 28; Convention against Torture, Article 7; Chemical Weapons Convention, Article VII(1); Amended Protocol II to the Convention on Certain Conventional Weapons, Article 14 ; Ottawa Convention, Article 9; Second Protocol to the Hague Convention for the Protection of Cultural Property, Articles 15–17.
[3] ICC Statute, preamble (cited in Vol. II, Ch. 44, § 134).
[4] In addition to those which refer to the grave breaches regime, see the military manuals of Australia (ibid., § 356), Cameroon (ibid., § 359), Canada (ibid., § 362), Colombia (ibid., § 363), Ecuador (ibid., § 365), Germany (ibid., § 369), Italy (ibid., § 370), Netherlands (ibid., § 373), Switzerland (ibid., § 381), United Kingdom (ibid., § 382), United States (ibid., §§ 383–384 and 387) and Yugoslavia (ibid., § 388).
[5] See, e.g., the practice of Algeria (ibid., § 533), Germany (ibid., § 540), Italy (ibid., § 541), South Africa (ibid., § 544), United Kingdom (ibid., § 547), United States (ibid., §§ 550–555) and Yugoslavia (ibid., § 556).
[6] See, e.g., Memorandum of Understanding on the Application of International Humanitarian Law between Croatia and the SFRY, Article 11 (ibid., § 343); Agreement on the Application of International Humanitarian Law between the Parties to the Conflict in Bosnia and Herzegovina, Article 5 (ibid., § 345); Comprehensive Agreement on Human Rights in Guatemala, Article III (ibid., § 347); the statements of Australia (ibid., § 534), German Democratic Republic (ibid., § 538), Germany (ibid., §§ 539–540), Italy (ibid., § 541), Slovenia (ibid., § 543), South Africa (ibid., § 544), United Kingdom (ibid., § 547), United States (ibid., §§ 550–554) and Yugoslavia (ibid., § 523); the reported practice of Algeria (ibid., § 533), Bosnia and Herzegovina (ibid., § 536) and United States (ibid., § 555).
[7] UN Security Council, Res. 978 (ibid., § 558), Res. 1193 (ibid., § 559) and Res. 1199 (ibid., § 560); UN Security Council, Statements by the President (ibid., §§ 561–569).
[8] UN General Assembly, Res. 3 (I) (ibid., § 570).
[9] UN General Assembly, Res. 2583 (XXIV) and 2712 (XXV) (ibid., § 571), Res. 2840 (XXVI) (ibid., § 572) and Res. 3074 (XXVIII) (ibid., § 573). These resolutions attracted substantial abstentions and a few negative votes. This was due, however, to States’ concern that there was insufficient clarity regarding the definition of war crimes and crimes against humanity and not, it seems, to any objection to the principle that war crimes be investigated and prosecuted.
[10] UN General Assembly, Res. 50/192 and 51/77 (ibid., § 575) and Res. 52/107 (ibid., § 576).
[11] UN Commission on Human Rights, Res. 1994/77 (ibid., § 578), Res. 1995/77 (ibid., § 583), Res. 1995/91 (ibid., § 584), Res. 1996/71 (ibid., § 580), Res. 1996/76 (ibid., § 584), Res. 1999/1 (ibid., § 585), Res. 1999/10 (ibid., § 586) and Res. 2000/58 (ibid., § 587). All resolutions were adopted without a vote, except Res. 1995/77 and Res. 2000/58, which attracted some negative votes and abstentions. It appears, however, that the reason for this does not lie in the inclusion of the duty to investigate and prosecute war crimes, as the other resolutions, which were adopted without a vote, also contained this duty.
[12] UN Commission on Human Rights, Res. 2002/79 (ibid., § 589).
[13] See, e.g., Argentina, Federal Judge, Cavallo case (ibid., § 700); Chile, Supreme Court, Saavedra case (ibid., § 701); Chile, Appeal Court of Santiago, Videla case (ibid., § 702); Ethiopia, Special Prosecutor’s Office, Mengistu and Others case (ibid., § 704); Spain, Sala de lo Penal de la Audiencia, Pinochet case (ibid., § 706); Inter-American Commission on Human Rights, Case 10.287 (El Salvador) (ibid., § 755); Inter-American Commission on Human Rights, Case 10.480 (El Salvador) (ibid., § 757); UN Security Council, Res. 1315 (ibid., § 725); UN Commission on Human Rights, Res. 2002/79 (ibid., § 734); UN Secretary-General, Report on the establishment of a Special Court for Sierra Leone (ibid., 738); UN Secretary-General, Report on the protection of civilians in armed conflicts (ibid., § 739).
[14] See the military manuals of Argentina (ibid., § 355), Australia (ibid., § 144), France (ibid., § 148) South Korea (ibid., § 149), Switzerland (ibid., §§ 156 and 381), United Kingdom (ibid., § 157), United States (ibid., §§ 159–160 and 369) and Yugoslavia (ibid., §§ 162 and 388); United Kingdom, House of Lords, Pinochet Extradition case (Opinion of Lord Phillips of Worth Matravers) (ibid., § 270); United States, Military Tribunal at Nuremberg, Altstötter (The Justice Trial) case (ibid., § 272); statements of Egypt (ibid., § 613), Islamic Republic of Iran (ibid., § 613), Pakistan (ibid., § 613), Saudi Arabia (ibid., § 613), Senegal (ibid., § 613), Turkey (ibid., § 613) and United Kingdom (ibid., § 287).
[15] ICC Statute, Article 8(2)(c) and (e) (ibid., § 3); ICTR Statute, Article 4 (ibid., § 15); Statute of the Special Court for Sierra Leone, Articles 3 and 4; Law on the Establishment of the Extraordinary Chambers in the Courts of Cambodia for the Prosecution of Crimes Committed during the Period of Democratic Kampuchea, Articles 6–7.
[16] Refugee Convention, Article 1(F)(a). See, e.g., Australia, Defence Force Manual (cited in Vol. II, Ch. 44, § 636); Netherlands, Council of State, Administrative Law Division, Ahmed case (ibid., § 638); United States, Court of Appeals, Demjanjuk case (ibid., § 639); the reported practice of Netherlands (ibid., § 640) and United States (ibid., § 641).
[17] UN Security Council, Statement by the President (ibid., § 642).
[18] UN General Assembly, Res. 2312 (XXII) (ibid., § 643) and Res. 3074 (XXVIII) (ibid., § 644).