Related Rule
New Zealand
Practice Relating to Rule 74. Chemical Weapons
New Zealand’s Military Manual (1992) states: “The 1925 Geneva Protocol prohibits the use in war of asphyxiating, poisonous and other gases, and bacteriological methods of warfare.” 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, §§ 512, 619 and 711.
The manual further includes “using asphyxiating, poisonous and other gases” in a list of “war crimes recognised by the customary law of armed conflict”. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1704(5).
New Zealand’s Chemical Weapons Act (1996) provides:
(1) Every person commits an offence who intentionally or recklessly
(a) Develops, produces, otherwise acquires, stockpiles or retains chemical weapons; or
(b) Transfers directly or indirectly, chemical weapons to another person; or
(c) Uses chemical weapons; or
(d) Engages in any military preparations to use chemical weapons; or
(e) Assists, encourages, or induces, in any way any person to engage in any activity prohibited to a State Party under the Convention. 
New Zealand, Chemical Weapons Act, 1996, Section 6, § 1.
Under New Zealand’s International Crimes and ICC Act (2000), war crimes include the crime defined in Article 8(2)(b)(xviii) of the 1998 ICC Statute. 
New Zealand, International Crimes and ICC Act, 2000, Section 11(2).
In 1980, during a debate in the UN General Assembly, New Zealand stated with respect to Resolution 35/144, which it had sponsored:
Of course, … no territorial limitations [for the investigations to be carried out by the UN Secretary-General into the alleged use of chemical weapons] are proposed. The Secretary-General is simply asked to look, with the assistance of qualified medical and technical experts, into all complaints of the alleged use of chemical weapons in military operations and to examine the evidence brought to his attention with a view to ascertaining the facts. 
New Zealand, Statement before the First Committee of the UN General Assembly, UN Doc. A/C.1/35/PV.45, 26 November 1980, p. 21.
In 1987, during a debate in the First Committee of the UN General Assembly, New Zealand condemned the use of chemical weapons against civilians. 
New Zealand, Statement before the First Committee of the UN General Assembly, UN Doc. A/C.1/42/PV.14, 21 October 1987, p. 34.
In 1989, in reply to a note verbale of the UN Secretary-General on the subject of chemical weapons, New Zealand declared that it did not possess chemical weapons. 
New Zealand, Reply to a note verbale of the UN Secretary-General, referred to in Report of the Secretary-General on respect for the right to life: elimination of chemical weapons, prepared in accordance with UN Sub-Commission on Human Rights Resolution 1988/27, UN Doc. E/CN.4/Sub.2/1989/4, 17 August 1989, § 98.
In its written statement submitted to the ICJ in the Nuclear Weapons case in 1995, New Zealand stated, with reference to customary IHL: “It is prohibited to use asphyxiating, poisonous or other gases and all analogous materials.” 
New Zealand, Written statement submitted to the ICJ, Nuclear Weapons case, 20 June 1995, § 72.
At the First Conference of States Parties to the Chemical Weapons Convention in 1997, New Zealand emphasized the importance of the 1993 Chemical Weapons Convention and stated its commitment and its determination to contribute actively to the realization of the Convention’s aims. 
New Zealand, Statement at the First Conference of States Parties to the Chemical Weapons Convention, The Hague, 6–23 May 1997.