Related Rule
Practice Relating to Rule 71. Weapons That Are by Nature Indiscriminate
At the CDDH, Italy stated:
There was nothing in paragraph 4 [of Article 46, now Article 51 of the 1977 Additional Protocol I] to show that certain methods or means of combat were prohibited in all circumstances by the Protocol except where an explicit prohibition was established by international rules in force for the State concerned with regard to certain weapons or methods. 
Italy, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.41, 26 May 1977, p. 164, § 122.