Règle correspondante
Practice Relating to Rule 44. Due Regard for the Natural Environment in Military Operations
In its oral pleadings before the ICJ in the Nuclear Weapons case in 1995, Qatar referred to the emergence within the international community “of an opinio juris concerning the preservation of the environment”. 
Qatar, Oral pleadings before the ICJ, Nuclear Weapons case, 10 November 1995, Verbatim Record CR 95/29, §§ 28–29.