Соответствующая норма
Mexico
Practice Relating to Rule 1. The Principle of Distinction between Civilians and Combatants
Section A. The principle of distinction
Mexico’s Army and Air Force Manual (2009), in a section on the 1977 Additional Protocol I, states: “The parties to a conflict must always distinguish between civilians and combatants.” 
Mexico, Manual de Derecho Internacional Humanitario para el Ejército y la Fuerza Área Mexicanos, Ministry of National Defence, June 2009, § 260.
In a section titled “Fundamental norms of international humanitarian law applicable in armed conflicts”, the manual also states: “Parties to a conflict must distinguish between the civilian population and combatants at all times in order to spare the civilian population.” 
Mexico, Manual de Derecho Internacional Humanitario para el Ejército y la Fuerza Área Mexicanos, Ministry of National Defence, June 2009, § 412.