Règle correspondante
Switzerland
Practice Relating to Rule 36. Demilitarized Zones
Switzerland’s Basic Military Manual (1987) states, with reference to Article 60 of the 1977 Additional Protocol I, that demilitarized zones can be established by military commanders of the parties to the conflict. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 12(2).
The manual points out that demilitarized zones, as well as non-defended localities, may be established through specific reciprocal declarations and that a unilateral declaration is not sufficient to create them. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 32(2) and (4).
The conditions for the setting-up of a demilitarized zone are the same as for non-defended localities, namely: all combatants as well as mobile weapons and military equipment must be evacuated; no hostile use shall be made of fixed military installations or establishments; no acts of hostility shall be committed by the authorities or by the population; any activity in support of the military effort must cease; and the zone must be marked by distinctive signs. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 32(2).
Switzerland’s ABC of International Humanitarian Law (2009) states:
Neutral territory/zone
Neutral territory is the territory of a State that is not party to a conflict and has chosen to remain neutral, either permanently or in relation to a given conflict.
Neutral territories are to be distinguished from neutral zones (neutralised zones, hospital and safety zones, and demilitarised zones) set aside within the territory of one or more parties to the conflict, for example to receive Wounded and sick as well as Civilians and non-combatants. 
Switzerland, Federal Department of Foreign Affairs, ABC of International Humanitarian Law, 2009, p. 31.
Switzerland’s Basic Military Manual (1987) prohibits attacks on demilitarized zones by any means. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 32(1).
The manual considers that demilitarized zones lose their protected status as soon as they are improperly used for military purposes. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 32(4).
The manual further provides that “launching an attack against … demilitarized zones” constitutes a grave breach of the 1977 Additional Protocol I. 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 193(1)(d).
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. 112
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 directs an attack against:
c. … demilitarized zones that are not military objectives. 
Switzerland, Military Criminal Code, 1927, taking into account amendments entered into force up to 2011, Articles 110 and 112(1)(c).
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. 264d
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 directs an attack against:
c. … demilitarized zones that are not military objectives. 
Switzerland, Penal Code, 1937, taking into account amendments entered into force up to 2011, Articles 264b and 264d (1)(c).