Related Rule
Switzerland
Practice Relating to Rule 146. Reprisals against Protected Persons
Section D. Civilians in the power of the adversary
Switzerland’s Basic Military Manual (1987), in the part dealing with “Hostilities and their limits” refers, inter alia, to Article 33 of the 1949 Geneva Convention IV and Articles 51, 54 and 55 of the 1977 Additional Protocol I and states: “Reprisals against the civilian population are prohibited.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 25(2).
In the part dealing with civilian persons and, more specifically, “civilian persons who are in the power of the troops at the moment of combat”, the manual refers to Article 33 of the 1949 Geneva Convention IV and states: “Measures of reprisal or attacks [carried out] as measures of reprisal are prohibited.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 149.
In a provision dealing with reprisals, the manual, referring to Article 33 of the 1949 Geneva Convention IV, states: “By virtue of the Geneva Conventions and their Additional Protocols, [reprisals] are prohibited with regard to … the civilian population”. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 197(2).
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
Foreign civilians or civilians of an adverse party to a conflict are specifically protected under the law of armed conflict. If they are in the hands of a military unit, they must at all times be treated humanely. Any act of torture, physical or mental ill-treatment, degrading treatment or discrimination as well as measures of reprisal are prohibited. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance on the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, § 198.
[emphasis in original]