States are obligated to assess the legality of weapons before fielding them in order to determine whether their employment would, in some or all circumstances, be prohibited.
- The obligation of States to determine the legality of weapons (including munitions) before employing them in battle is longstanding. The State employing the weapons does not need to conduct the legal review itself. However, the fact that an assessment has already been performed by the State which developed or provided them — or from which they were acquired — does not relieve the State employing them of its responsibility to field only lawful weapons.
- For Contracting Parties to AP/I, Art. 36 extends the requirement to a review of new “method[s]” of warfare. Further, the review is required during the “study, development, acquisition or adoption” phases. However, there is little State practice in either regard.
- Although (as stated in paragraph 1 of the Commentary on the chapeau of Section C), the requirement of a review of new weapons is applicable only in international armed conflicts, this does not relieve the State of its responsibility to field only lawful weapons in non-international armed conflicts.
- Art. 1 of the 1899 Hague Convention (II): “The High Contracting Parties shall issue instructions to their armed land forces, which shall be in conformity with the “Regulations respecting the laws and customs of war on land” annexed to the present Convention.”
The latter Regulations included (Art. 23 (e)) the prohibition to “employ arms, projectiles, or material of a nature to cause superfluous injury” (see fn. 136).
This was repeated, with non-substantive alteration, in Art. 1 of the 1907 Hague Convention (IV): “The Contracting Powers shall issue instructions to their armed land forces which shall be in conformity with the Regulations respecting the laws and customs of war on land, annexed to the present Convention.”, with Art. 23 (e) of the 1907 Hague Regulations stating that it was forbidden “to employ arms, projectiles, or material calculated to cause unnecessary suffering.” (see fn. 137).
- Art. 36 of AP/I states: “In the study, development, acquisition or adoption of a new weapon, means or method of warfare, a High Contracting Party is under an obligation to determine whether its employment would, in some or all circumstances, be prohibited by this Protocol or by any other rule of international law applicable to the High Contracting Party.”
Categories: Section C: Weapons