Related Rule
Colombia
Practice Relating to Rule 70. Weapons of a Nature to Cause Superfluous Injury or Unnecessary Suffering
Colombia’s Circular on Fundamental Rules of IHL (1992) provides: “Using weapons or methods of warfare which can cause superfluous injury or unnecessary suffering is prohibited.” 
Colombia, Transcripción Normas Fundamentales del Derecho Humanitario Aplicables en los Conflictos Armados, Circular No. 033/DIPL-SERPO-526, Policía Nacional, Dirección General, Santafé de Bogotá, 14 May 1992, § 6.
Colombia’s Basic Military Manual (1995) states that employing weapons which “cause unnecessary and indiscriminate, extensive, lasting and serious damage to people” is prohibited. 
Colombia, Derecho Internacional Humanitario – Manual Básico para las Personerías y las Fuerzas Armadas de Colombia, Ministerio de Defensa Nacional, 1995, pp. 49–50.
Colombia’s Decree on the Control of Firearms, Ammunition and Explosives (1993) states that firearms which have undergone substantial modification in manufacture or origin to make them more deadly are prohibited. 
Colombia, Decree on the Control of Firearms, Ammunition and Explosives, 1993, Article 14(b).
Colombia’s Penal Code (2000) imposes a criminal sanction on “anyone who, during an armed conflict, uses means and methods of warfare … whose aim is to cause unnecessary suffering and loss or superfluous injury”. 
Colombia, Penal Code, 2000, Article 142.
In 2006, in the Constitutional Case No. T-165/06, the First Appeals Chamber of Colombia’s Constitutional Court stated:
[The principles of distinction, limitation and proportionality] are found throughout IHL. Regarding the protection of victims in international or non-international armed conflicts, they materialize in concrete rules, such as … [the one] that: prohibits the use of weapons, projectiles, material and methods of warfare of a nature to cause superfluous or unnecessary suffering. 
Colombia, Constitutional Court, Constitutional Case No. T-165/06, Judgment of 7 March 2006, p. 8
[footnote in original omitted]
In 1975, during discussions in the Ad Hoc Committee on Conventional Weapons established by the CDDH, the representative of Colombia stated:
8. … His government … supported all measures for the prohibition or limitation of the use of conventional weapons likely to cause unnecessary injury …
9. … His Government was opposed to the use of napalm and incendiary weapons. In view of the suffering inflicted on the victims, nothing could justify their use. Similarly, the use of high velocity small-calibre projectiles designed to cause excessive injury should be absolutely forbidden. Such weapons were indeed comparable to explosive bullets or dum-dum bullets. 
Colombia, Statement at the CDDH, Official Records, Vol. XVI, CDDH/IV/SR.14, 5 March 1975, p. 132, §§ 8–9.
In 1977, during a debate in the First Committee of the UN General Assembly, Colombia advocated the elimination of “weapons of mass destruction, chemical and bacteriological weapons, incendiary weapons and all those weapons that are capable of bringing about the most horrifying suffering”. 
Colombia, Statement before the First Committee of the UN General Assembly, UN Doc. A/C.1/ 32/PV.21, 5 October 1977, p. 11.