Related Rule
New Zealand
Practice Relating to Rule 47. Attacks against Persons Hors de Combat
New Zealand’s Military Manual (1992) states: “A person who is recognised as, or who in the circumstances should be recognised as, hors de combat shall not be made the object of attack.” 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 503(2) (land warfare); see also § 612(2) (air warfare).
Furthermore, the manual states that “making a person the object of attack knowing he is hors de combat” is a grave breach of the 1977 Additional Protocol I and a war crime. The manual explains that “this has always been a war crime under customary law”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 1701(1) and 1703(3)(e), including footnote 17.
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 [the 1977 Additional Protocol I] is guilty of an indictable offence. 
New Zealand, Geneva Conventions Act, 1958, as amended in 1987, Section 3(1).
New Zealand’s Military Manual (1992) provides:
A person who is recognised as, or who in the circumstances should be recognised as, hors de combat shall not be made the object of attack. A person is hors de combat if:
a) he is in the power of an adverse Party;
b) he clearly expresses an intention to surrender; or
c) he has been rendered unconscious or is otherwise incapacitated by wounds or sickness, and is therefore incapable of defending himself;
provided that in any of these cases he abstains from any hostile act and does not attempt to escape. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 503(2) (land warfare); see also § 612(2) (air warfare).
The manual further states that “killing or wounding an enemy who, having laid down his arms or no longer having a means of defence, has accordingly surrendered” is a war crime. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1704(2)(c).
Likewise, “among other war crimes recognised by the customary law of armed conflict are … firing upon shipwrecked personnel”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1704(5).
Under New Zealand’s International Crimes and ICC Act (2000), war crimes include the crimes defined in Article 8(2)(b)(vi) of the 1998 ICC Statute. 
New Zealand, International Crimes and ICC Act, 2000, Section 11(2).