Related Rule
Spain
Practice Relating to Rule 22. The Principle of Precautions against the Effects of Attacks
Section B. Feasibility of precautions against the effects of attacks
Upon ratification of the 1977 Additional Protocol I, Spain interpreted the term “feasible” as meaning that “the matter in question is feasible or possible in practice, taking into account all the circumstances prevailing at the time, including humanitarian and military aspects”. 
Spain, Interpretative declarations made upon ratification of the 1977 Additional Protocol I, 21 April 1989, § 3.