Related Rule
South Africa
Practice Relating to Rule 158. Prosecution of War Crimes
South Africa’s LOAC Manual (1996) states: “Signatory States [of the 1949 Geneva Conventions] are required to treat as criminals under domestic law anyone who commits or orders a grave breach [of the 1949 Geneva Conventions].” 
South Africa, Presentation on the South African Approach to International Humanitarian Law, Appendix A, Chapter 4: International Humanitarian Law (The Law of Armed Conflict), National Defence Force, 1996, § 35.
The manual further states:
Grave breaches of the law of war are regarded as war crimes. They shall be repressed by penal sanctions …
Grave breaches are indictable offence[s] under Section 7 of the Geneva Conventions Act, RSA, 1957. South Africa is obliged to search out and prosecute or extradite those who have committed a grave breach. For all breaches (i.e. violations of the law of war), South Africa has an obligation to take steps to ensure that the offences do not happen again … If breaches went unpunished, it would signify the degradation of human values and the regression of the entire concept of humanity. 
South Africa, Presentation on the South African Approach to International Humanitarian Law, Appendix A, Chapter 4: International Humanitarian Law (The Law of Armed Conflict), National Defence Force, 1996, §§ 41 and 42.
South Africa’s Revised Civic Education Manual (2004) states: “South Africa is obliged to search out and prosecute or extradite those who have committed a grave breach [of the law of armed conflict].” 
South Africa, Revised Civic Education Manual, South African National Defence Force, 2004, Chapter 4, § 57.
In its judgment in the Basson case in 2004, the Constitutional Court of South Africa stated that “international law obliges the state to punish crimes against humanity and war crimes”. 
South Africa, Constitutional Court, Basson case¸ Judgment, 10 March 2004, § 37.
In the same case, Justice Sachs wrote in his concurring opinion:
The duty of states to provide effective penal sanctions today for persons involved in grave breaches of humanitarian law, whenever committed, is captured and expressed in Article 146 of the Fourth Geneva Convention of 1949 (articles 146–147 appear with different numbering in all four conventions). 
South Africa, Constitutional Court, Basson case¸ Judgment, 10 March 2004, § 123.
In 1998, in its report on “gross violations of human rights” committed between 1960 and 1993, South Africa’s Truth and Reconciliation Commission stated:
Those combatants who were killed or seriously injured while they were unarmed or out of combat, executed after they had been captured, or wounded when they clearly could have been arrested were held to be victims of gross violations of human rights, and those responsible were held accountable. 
South Africa, Report of the Truth and Reconciliation Commission, 1998, Vol. 1, p. 76, § 102.