Related Rule
Belgium
Practice Relating to Rule 70. Weapons of a Nature to Cause Superfluous Injury or Unnecessary Suffering
Belgium’s Law of War Manual (1983) provides that the use of weapons or means and methods of warfare which render death inevitable or cause unnecessary suffering is illegal. 
Belgium, Droit Pénal et Disciplinaire Militaire et Droit de la Guerre, Deuxième Partie, Droit de la Guerre, Ecole Royale Militaire, par J. Maes, Chargé de cours, Avocat-général près la Cour Militaire, D/1983/1187/029, 1983, p. 37.
Belgium’s Teaching Manual for Officers (1994) defines the concept of unnecessary suffering as “suffering … that needlessly adds to that already inflicted on the enemy to render him hors de combat”. It provides: “It is prohibited to use weapons for the purpose of causing superfluous injury rather than for their military effectiveness.” 
Belgium, Droit de la Guerre, Manuel d’Instruction pour Officiers, Etat-Major Général, Division Opérations, 1994, p. 36, § 17(1).
Belgium’s Teaching Manual for Soldiers states: “Combatants must refrain from causing superfluous injury or unnecessary suffering to persons and unnecessary damage to property.” 
Belgium, Droit de la Guerre, Dossier d’Instruction pour Soldat, à l’attention des officiers instructeurs, JS3, Etat-Major Général, Forces Armées belges, undated, p. 11.
Belgium’s Penal Code (1867), as amended in 2003, provides:
War crimes envisaged in the 1949 [Geneva] Conventions … and in the [1977 Additional Protocols I and II] … , as well as in Article 8(2)(f) of the [1998 ICC Statute], and listed below, … constitute crimes under international law and shall be punished in accordance with the provisions of the present title … :
40. employing weapons, projectiles, material and methods of warfare which are of a nature to cause superfluous injury or unnecessary suffering … in violation of the international law of armed conflict, provided that such weapons, projectiles, material and methods of warfare are the subject of a comprehensive prohibition and are included in an annex to the Statute of the International Criminal Court. 
Belgium, Penal Code, 1867, as amended on 5 August 2003, Chapter III, Title I bis, Article 136 quater, § 1(40).
Belgium’s Law relating to the Repression of Grave Breaches of International Humanitarian Law (1993), as amended in 2003, provides:
War crimes envisaged in the 1949 [Geneva] Conventions … and in the [1977 Additional Protocols I and II] … , as well as in Article 8(2)(f) of the [1998 ICC Statute], and listed below, … constitute crimes under international law and shall be punished in accordance with the provisions of the present title … :
26. employing weapons, projectiles, material and methods of warfare which are of a nature to cause superfluous injury or unnecessary suffering … in violation of the international law of armed conflict, provided that such weapons, projectiles, material and methods of warfare are the subject of a comprehensive prohibition and are included in an annex to the Statute of the International Criminal Court. 
Belgium, Law relating to the Repression of Grave Breaches of International Humanitarian Law, 1993, as amended on 23 April 2003, Article 1 ter, § 1(26).