Related Rule
New Zealand
Practice Relating to Rule 89. Violence to Life
New Zealand’s Military Manual (1992) prohibits killing and provides: “Self-preservation or military necessity can never provide an excuse for the murder of prisoners of war.” 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 919(1).
The manual further states that “wilful killing” is a grave breach of the 1949 Geneva Conventions and their 1977 Additional Protocols. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 1137(1), 1702(1) and 1704(2-c); see also § 1704(5) (genocide as an offence against the law of armed conflict and a war crime).
With respect to non-international armed conflicts, the manual restates the provisions of common Article 3 of the 1949 Geneva Conventions. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1807(1)(d).
New Zealand’s Geneva Conventions Act (1958), as amended in 1987, provides: “Any person who in New Zealand or elsewhere commits, or aids or abets or procures the commission by another person of, a grave breach of any of the [1949 Geneva] Conventions … is guilty of an indictable offence.” 
New Zealand, Geneva Conventions Act, 1958, as amended in 1987, Section 3(1).
Under New Zealand’s International Crimes and ICC Act (2000), genocide includes the crimes defined in Article 6(a) of the 1998 ICC Statute, crimes against humanity include the crimes defined in Article 7(1)(a) of the Statute, and war crimes include the crimes defined in Article 8(2)(a)(i) and 8(2)(c)(i) and (iv) of the Statute. 
New Zealand, International Crimes and ICC Act, 2000, Sections 9(2), 10(2) and 11(2).