Related Rule
Colombia
Practice Relating to Rule 77. Expanding Bullets
In 1995, in a ruling on the constitutionality of the 1977 Additional Protocol II, the Constitutional Court of Colombia stated in relation to the prohibition on the use of weapons of a nature to cause unnecessary suffering or superfluous injury:
Although none of the treaty rules expressly applicable to internal conflicts prohibits indiscriminate attacks or the use of certain weapons, the Taormina Declaration consequently considers that the bans (established partly by customary law and partly by treaty law) on the use of … “dum-dum” bullets … apply to non-international armed conflicts, not only because they form part of customary international law but also because they evidently derive from the general rule prohibiting attacks against the civilian population. 
Colombia, Constitutional Court, Constitutional Case No. C-225/95, Judgment, 18 May 1995.
In 1975, during discussions in the Ad Hoc Committee on Conventional Weapons established by the CDDH on the legality of high-velocity weapons, Colombia stated: “Such weapons were indeed comparable to … dum-dum bullets … It was thus essential to expedite the formulation of rules prohibiting their use.” 
Colombia, Statement at the CDDH, Official Records, Vol. XVI, CDDH/IV/SR.14, 5 March 1975, pp. 132–133, § 9.