Related Rule
Practice Relating to Rule 145. Reprisals
Mexico’s Army and Air Force Manual (2009) states: “During the course of a war, a State may take reprisals against the enemy when it has violated international law only for the purpose of deterring it from doing it again in the future.” 
Mexico, Manual de Derecho Internacional Humanitario para el Ejército y la Fuerza Área Mexicanos, Ministry of National Defence, June 2009, § 384.
At the CDDH, in an explanation of vote, Mexico stated:
The delegation of Mexico could not have accepted that a Protocol intended to strengthen the law concerning warlike activities should authorize reprisals, even if it were claimed that the intention was to force the enemy to respect humanitarian law … Experience shows that reprisals do not lead the enemy to respect humanitarian law, but result in an increase in violations and hostilities.
Legalization of reprisals, as proposed by France, would have enabled belligerents who were in breach of humanitarian law to claim every time that their breach was a legitimate reprisal sanctioned by international law. The delegation of Mexico believes that the mandatory nature of humanitarian law does not depend from the observance of its rules by the adverse Party, but stems from the inherently wrongful nature of the act prohibited by international humanitarian law. The Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, unanimously adopted by the United Nations General Assembly in its resolution 2625 (XXV) of 24 October 1970, prohibits reprisals involving the use of force. The delegation of Mexico maintains that this Declaration is a valid interpretation of the United Nations Charter, so that the prohibition in question is legally binding. 
Mexico, Statement at the CDDH, Official Records, Vol. IX, CDDH/I/SR.73, 16 May 1977, pp. 449–450.
In its oral pleadings before the ICJ in the Nuclear Weapons case in 1995, Mexico stated: “In the opinion of my country the use of nuclear weapons in reprisal – or any other pretext – against a non-nuclear attack is contrary to the principle of proportionality.” 
Mexico, Oral pleadings before the ICJ, Nuclear Weapons case, CR 95/25, 3 November 1995, p. 51.