This paper examines whether a principle of unnecessary suffering exists with legal meaning as an independent, binding norm in international humanitarian law. Further, the legal impacts as such, and its legal status in relation to conventional prohibitive rules on specific weapons are investigated. These legal matters are explored through examinations of the treaties signed before World War II that forbids specific weapons based on this principle. The principle of unnecessary suffering, which forbids employment of weapons, projectiles and materials and methods of warfare of a nature that would cause superfluous injury or unnecessary suffering is a well-established and longstanding principle of international humanitarian law. The principle has not only stood as a cardinal principle in international humanitarian law but also represented a law of humanity itself. However, the principle has been criticized for lack of clear definition regarding what constitutes “unnecessary” and for what purpose. Because of its vagueness, some argue that the principle is hollow and lacks legal meaning as an enforceable rule, as it does not entail a specific ban or restrictions on weapons through conventional stipulations. This paper contends that the general principle has legal impact in three ways: (1) its mutual complementary legal character toward specific ban approach, (2) the existence of a legal rule forbidding certain weapons in the form of customary law and (3) providing a legal
basis for an analogic approach to prohibiting certain weapons in international humanitarian law.