Related Rule
Practice Relating to Rule 70. Weapons of a Nature to Cause Superfluous Injury or Unnecessary Suffering
In 1970, during a debate in the Third Committee of the UN General Assembly on Resolution 2677 (XXIV), which emphasized the need to “secure the full observance of human rights applicable in all armed conflicts” and called upon “all parties to any armed conflict to observe the rules laid down in the Hague Conventions of 1899 and 1907, the Geneva [Gas] Protocol of 1925 … and other humanitarian rules applicable in armed conflicts”, India sought to change “all armed conflicts” in the second preambular paragraph to “armed conflicts”. Being unsuccessful, it then stated that it construed the expression “all armed conflicts” to denote all international armed conflicts. 
India, Statement before the Third Committee of the UN General Assembly, UN Doc. A/C.3/SR.1801, 27 November 1970, p. 379.
In 1976, during discussions in the Ad Hoc Committee on Conventional Weapons established by the CDDH, India stated that it was
happy to note that all the delegations agreed in recognizing the need to avoid unnecessary suffering and that the differences of opinion concerned solely the extent to which countries were prepared to restrict their choice of that type of weapon for their defense, in order to avoid unnecessary suffering to civilians and combatants. 
India, Statement at the CDDH, Official Records, Vol. XVI, CDDH/IV/SR.28, 20 May 1976, p. 284, § 5.
At the CDDH, India stated that it had agreed to join in the consensus on Article 33 of the draft Additional Protocol I (now Article 35),
with the understanding that the basic rules contained in this article will apply to all categories of weapons, namely nuclear, bacteriological, chemical, or conventional weapons or any other category of weapons. Secondly, the term “superfluous injury or unnecessary suffering” means those physical injuries which are more severe than would be necessary to render an adversary hors de combat or to make the enemy surrender and which are not justified by considerations of military necessity. 
India, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.39, 25 March 1977, p. 115.
In its written statement submitted to the ICJ in the Nuclear Weapons case in 1995, India stated:
The use of nuclear weapons in an armed conflict is unlawful, being contrary to the conventional as well as customary international law because such a use … could cause excessive injuries to the combatants making their death inevitable. 
India, Written statement submitted to the ICJ, Nuclear Weapons case, 20 June 1995, p. 4.
The Report on the Practice of India states that India considers that the prohibition of weapons causing unnecessary suffering also applies in non-international armed conflicts. 
Report on the Practice of India, 1997, Chapter 3.1.