Related Rule
Practice Relating to Rule 72. Poison and Poisoned Weapons
Mexico’s Army and Air Force Manual (2009) states: “It is prohibited to use poison and poisoned arms”. 
Mexico, Manual de Derecho Internacional Humanitario para el Ejército y la Fuerza Área Mexicanos, Ministry of National Defence, June 2009, § 411.
Mexico’s IHL Guidelines (2009), in a section entitled “Basic rules of conduct in armed conflict”, states: “Do not use poison”. 
Mexico, Cartilla de Derecho Internacional Humanitario, Ministry of National Defence, 2009, § 14(k).
In its written statement submitted to the ICJ in the Nuclear Weapons case in 1995, Mexico referred to “a series of international instruments … [which] led to a prohibition on the use of certain weapons. Such instruments included the Hague Conventions of 1899 and 1907, which prohibited the use of poisoned or poisonous weapons.” 
Mexico, Written statement submitted to the ICJ, Nuclear Weapons case, 19 June 1995, p. 12, § 72.
In 2009, Mexico submitted a proposal to the UN Secretary General to amend Article 8(2)(c) of the 1998 ICC Statute in accordance with Article 121(1) of the Statute, stating:
Within the category of serious violations of the laws and customs applicable in international armed conflicts, the use of certain weapons whose effects are of an indiscriminate nature or cause superfluous injury or unnecessary suffering is included. Such weapons are: a) poison or poisoned weapons; [and] b) asphyxiating, poisonous or other gases, and all analogous liquids, materials and devices … The use of these … kinds of weapons is prohibited by conventional and customary international law. 
Mexico, Proposal of Amendment to Article 8(2)(c) of the 1998 ICC Statute, submitted to the UN Secretary General in accordance with Article 121(1) of the ICC Statute, 29 September 2009, p. 2.
[footnotes in original omitted]