Related Rule
Germany
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section C. Feasibility of precautions in attack
Upon ratification of the 1977 Additional Protocol I, Germany stated that it understood the word “feasible” to mean “that which is practicable or practically possible, taking into account all circumstances ruling at the time, including humanitarian and military considerations”. 
Germany, Declarations made upon ratification of the 1977 Additional Protocol I, 14 February 1991, § 2.