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Switzerland
Practice Relating to Rule 14. Proportionality in Attack
Switzerland’s Basic Military Manual (1987) states: “If the military advantage is not proportionate to the damage [suffered by the civilian population], [commanders] must cancel an attack”. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 29(1).
The manual further states that “an attack which is launched without making any distinction [between civilians and civilian objects on the one hand and military objectives on the other hand] and which may affect the civilian population or civilian objects in the knowledge that the attack will cause loss of human life, injuries to civilians and damage to civilian objects which would be excessive in the sense of Article 57(2)(a)(iii) [of the 1977 Additional Protocol I]” constitutes a grave breach. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 193(1)(b).
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
12 The four basic principles of the international law of armed conflict
158 …
- the principle of proportionality;
12.3 Principle of proportionality
163 Military action is only permissible if the loss of human life and damage to civilian or specially protected objects are not excessive in relation to the concrete and direct military advantage anticipated. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance for the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, §§ 158 and 163. The German language version notes in § 163: “… if the loss of human life and damage to civilian or, respectively, specially protected objects caused or to be anticipated are reasonable in relation to the military advantage concretely to be anticipated [“… wenn die dadurch verursachten oder zu erwartenden Verluste an Menschenleben sowie Schäden an zivilen bzw. speziell geschützten Objekten zum konkret zu erwartenden militärischen Vorteil in einem vernünftigen Verhältnis stehen.”]”.
The Regulation also explains with respect to the situation of a “[c]onvoy of refugees intermingled with some combatants” that, in application of the principle of proportionality, the “concrete military advantage is not in an acceptable proportion”. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance for the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, § 172.
Switzerland’s Military Criminal Code (1927), taking into account amendments entered into force up to 2011, states in a chapter entitled “War crimes”:
Art. 110
Articles 112–114 apply in the context of international armed conflicts, including in situations of occupation, and, if the nature of the offence does not exclude it, in the context of non-international armed conflicts.
Art. 112c
1 The penalty shall be a custodial sentence of not less than three years for any person who, in the context of an armed conflict:
a. launches an attack although he knows or must assume that such an attack will cause loss of life or injury to civilians or damage to civilian objects or widespread, long-term and severe damage to the natural environment which would be excessive in relation to the concrete and direct military advantage anticipated. 
Switzerland, Military Criminal Code, 1927, taking into account amendments entered into force up to 2011, Articles 110 and 112c (1)(a).
Switzerland’s Penal Code (1937), taking into account amendments entered into force up to 2011, states under the title “War crimes”:
Art. 264b
Articles 264d–264j apply in the context of international armed conflicts, including in situations of occupation, and, if the nature of the offence does not exclude it, in the context of non-international armed conflicts.
Art. 264g
1 The penalty shall be a custodial sentence of not less than three years for any person who, in the context of an armed conflict:
a. launches an attack although he knows or must assume that such an attack will cause loss of life or injury to civilians or damage to civilian objects or widespread, long-term and severe damage to the natural environment which would be excessive in relation to the concrete and direct military advantage anticipated. 
Switzerland, Penal Code, 1937, taking into account amendments entered into force up to 2011, Articles 264b and 264g (1)(a).
In 2005, in a report in response to a parliamentary postulate on private security and military companies, Switzerland’s Federal Council stated: “International humanitarian law also limits the conduct of military operations permissible under international law. … Attacks against military targets are also forbidden if there’s a chance that civilians or civilian objects would be disproportionately affected.” 
Switzerland, Report by the Swiss Federal Council on Private Security and Military Companies, 2 December 2005, Section 5.3.1, pp. 45–46.
Switzerland’s ABC of International Humanitarian Law (2009) states:
Conduct of hostilities
Not all Means and methods of warfare are allowed in an Armed conflict. International humanitarian law stipulates the military operations, tactics and weapons that are permissible. The two generally accepted principles of Distinction and Proportionality are the basis for a number of specific rules such as the prohibition of direct attacks on the civilian population or on Civilian objects, the prohibition of indiscriminate attacks and the obligation to adopt precautionary measures (Precaution) so as to avoid or limit casualties among Civilians and damage to civilian objects to the greatest possible extent.
Proportionality
The principle of proportionality applies to every aspect of the conduct of hostilities. It is prohibited for example to carry out attacks against a Military objective that would cause a disproportionate amount of harm to the civilian population, and against Civilian objectives. Before launching an attack there is an obligation to assess whether or not the impact on the civilian population is excessive in relation to the concrete and direct military advantage anticipated. 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, pp. 13–14 and 36. In the French version of this brochure, the sentence “It is prohibited for example to carry out attacks against a Military objective that would cause a disproportionate amount of harm to the civilian population, and against Civilian objectives” reads “Les attaques susceptibles de causer des dommages disproportionnés dans la population civile ou aux biens civils sont ainsi interdites même si elles sont dirigées contre des objectifs militaires” (see ABC du Droit International Humanitaire, 2014, 2nd revised edition, p. 44).
In 2009, in a statement before the UN Security Council during an open debate on the protection of civilians in armed conflict, the permanent representative of Switzerland stated:
The current situation in Gaza cries out to us the importance of the issue we are discussing today. The main victims of the Israeli-Palestinian conflict are civilians. Switzerland is deeply shocked by the very high number of civilians that have been killed or wounded in this conflict, and in particular the high number of child victims. …
Switzerland therefore reiterates its call for … strict compliance with international law by all parties to the conflict. This includes in particular the obligation to respect the principles of distinction, proportionality and precaution. 
Switzerland, Statement by the permanent representative of Switzerland before the UN Security Council on the protection of civilians in armed conflict, 14 January 2009, p. 5.
In 2009, in its Report on Foreign Policy, Switzerland’s Federal Council stated: “The recourse to practices contrary to international law, such as … non-respect for the principle of proportionality, [is] among the strategies used by the parties in conflict.” 
Switzerland, Federal Council, Report on Foreign Policy 2009, 2 September 2009, Section 3.3.7.2, p. 5807.
In 2010, in its Report on IHL and Current Armed Conflicts, Switzerland’s Federal Council stated:
3.2 Increasing technification of war
… The weapon technologies used do not call into question the applicable principles of international humanitarian law. … Moreover, attacks must not cause incidental loss of human life among the civilian population in relation to the concrete and direct military advantage anticipated, nor lead to excessive suffering. These fundamental principles are always applicable to all types and systems of weapons. …
3.5 Moving of combat zones towards the civilian population
… Collateral damage is not prohibited as long as it is not disproportionate. …
4 Possibilities of international humanitarian law development
As the preceding analysis underlines, international humanitarian law maintains its relevance for most of the aspects of current armed conflicts. The fundamental principles such as distinction and proportionality remain valid in guerrilla warfare, which represents today the main form of conducting war. These principles constitute a permanent requirement that cannot be called into question, not even by widespread non-respect by the parties to a conflict. 
Switzerland, Federal Council, Report on IHL and Current Armed Conflicts, 17 September 2010, Sections 3.2, 3.5 and 4, pp. 9, 16 and 18–19.
In 2010, in its Report on Foreign Policy, Switzerland’s Federal Council stated: “The recourse to practices contrary to international law, such as … non-respect for the principle of proportionality, … [is] among the strategies used by the parties in conflict.” 
Switzerland, Federal Council, Report on Foreign Policy 2010, 10 December 2010, Section 4.2.1, p. 1083.
In 2012, Switzerland’s Federal Department of Foreign Affairs issued a press release entitled “Appeal by the Swiss authorities for compliance with international humanitarian law in Syria”, which stated:
Deep concern about the humanitarian situation
2. Switzerland expresses its deep concern about the deterioration of the humanitarian situation in Syria. It deplores the high number of civilian casualties caused by violations of international humanitarian law, in particular as a result of the indiscriminate and disproportionate use of force.
International humanitarian law is applicable to non-international armed conflict.
4. International humanitarian law is applicable in non-international armed conflicts. All parties to the conflict are therefore obliged to respect its rules in all circumstances, including the rules protecting persons who are [not] or are no [longer] participating in the hostilities, as well as the rules relative to the means and methods of warfare. …
Appeal to respect international rules
7. [Switzerland] recalls that in the conduct of military operations, all feasible precautions must be taken with a view to avoid incidental loss of civilian life[,] injury to civilians and damage to civilian objects and collateral damage to civilian property. All parties are subject to the obligation to respect the principles of distinction, proportionality and precaution. 
Switzerland, Federal Department of Foreign Affairs, “Appeal by the Swiss authorities for compliance with international humanitarian law in Syria”, Press Release, 15 November 2012.
In 2013, in answer to an interpellation in Parliament regarding the use of drones, Switzerland’s Federal Council stated:
In armed conflicts, strikes carried out with armed drones must respect the rules of the conduct of hostilities as stipulated by international humanitarian law, including the principles of distinction, proportionality and precaution, and must therefore not be directed against civilians or civilian objects. For each strike, it is thus necessary to verify that these principles were respected. 
Switzerland, Answer by the Federal Council to interpellation 13.3245 in Parliament regarding the use of drones, 29 May 2013.
In 2013, in a statement at the Meeting of the High Contracting Parties to the 1980 Convention on Certain Conventional Weapons, the permanent representative of Switzerland stated:
The community of States cannot remain indifferent to the human suffering caused by armed conflicts. It was in direct response to this fundamental concern that the CCW [1980 Convention on Certain Conventional Weapons] and its protocols were adopted, with a view to prohibiting or limiting the use of certain specific types of weapons known to inflict superfluous injury or unnecessary suffering, or to strike indiscriminately.
In this regard, Switzerland is deeply concerned by the alleged use of weapons in Syria falling within the ambit of the CCW and its respective protocols, such as the alleged use of anti-personnel mines as well as the alleged use of incendiary weapons in populated areas causing severe human suffering. We call upon all parties to the conflict to comply with their obligations under international law, in particular the principles of distinction, precaution, and proportionality. 
Switzerland, Statement by the permanent representative of Switzerland at the Meeting of the High Contracting Parties to the Convention on Certain Conventional Weapons, 14 November 2013.