Practice Relating to Rule 140. The Principle of Reciprocity
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
The international law of armed conflict is based on the principle of reciprocity: i.e. “Do not do to others what you do not want done to you”. Respect for the rules of the international law of armed conflict based on the principle of reciprocity benefits both the parties involved in a conflict and the civilian population. Violation of these rules by the enemy under no circumstances justifies one’s own deviation from the rules of the international law of armed conflict.
In 2008, in its response to a question by a member of the National Council, Switzerland’s Federal Council wrote:
3. As depository state and contracting party to the  Geneva Conventions, Switzerland wishes to underline the importance of respect for international humanitarian law by all the parties to the conflict, whether this concerns state armed forces, armed groups or individuals. Its call to respect international norms is thus addressed to all the parties to the Israeli-Palestinian conflict.
Israel has the right and the duty to protect its territory and population against attacks. However, as a party to the conflict, it is bound by the obligations emanating from international humanitarian law. Furthermore, disrespect of the rules of international humanitarian law by one party to the conflict cannot legitimize violations of the law by the other party.
Switzerland’s ABC of International Humanitarian Law (2009) states:
The parties to a conflict must respect international humanitarian law in all circumstances and regardless of the behaviour of the other side. A State Party cannot evade its own obligations arguing that the other Party is failing to uphold international humanitarian law. Thus a State Party accused of a violation cannot justify its actions on the grounds that the other Party committed a similar violation.
In 2010, in its Report on IHL and Current Armed Conflicts, Switzerland’s Federal Council stated:
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 wars, which represent today the main form of conducting war. These principles represent a permanent requirement that cannot be called into question, not even by notorious non-respect by the parties to a conflict.
[footnotes in original omitted]