Règle correspondante
Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
Section A. Cooperation between States
Switzerland’s Federal Act on International Mutual Assistance (1981), as amended to 2010, states in its general provisions:
1. Unless other federal acts or international agreements provide otherwise, this Act shall govern all procedures of international cooperation in criminal matters, and in particular:
b. assistance aimed at supporting criminal proceedings abroad (Part Three);
c. the transfer of proceedings and punishment of offences (Part Four);
d. the execution of foreign criminal judgments (Part Five).
3. This Act applies only to criminal matters in which recourse to the courts is permitted under the law of the requesting State.
4. This Act confers no right to international cooperation in criminal matters. 
Switzerland, Federal Act on International Mutual Assistance, 1981, as amended to 2010, Article 1(1) and (3)–(4).
[footnotes in original omitted]
The Act further states:
Art. 2 Foreign proceedings
A request for cooperation in criminal matters shall not be granted if there are reasons to believe that the foreign proceedings
a. do not meet the procedural requirements of the European Convention for the Protection of Human Rights and Fundamental Freedoms of 4 November 1950, or the International Covenant on Civil and Political Rights of 16 December 1966;
b. are being conducted so as to prosecute or punish a person on account of his or her political opinions, his or her belonging to a certain social group, his or her race, religion, or nationality;
c. could result in aggravating the situation of the defendant for any of the reasons mentioned under letter b; or
d. have other serious defects.
Art. 3 Nature of the offence
1. A request shall not be granted if the subject of the proceedings is an act which, in the Swiss view, is of a predominantly political nature, constitutes a violation of the obligation to perform military or similar service, or appears to be directed against the national security or military defence of the requesting State.
2. The plea that an act is of a political nature shall not be taken into account under any circumstances:
a. in cases of genocide;
b. in cases of crimes against humanity;
c. in cases of war crimes; or
d. if the act appears particularly reprehensible because the offender, for the purpose of extortion or duress, has endangered or threatened to endanger the life or limb of persons, especially by hijacking aircraft, using means of mass extermination, causing a catastrophe or taking hostages. 
Switzerland, Federal Act on International Mutual Assistance, 1981, as amended to 2010, Articles 2 and 3.
[footnotes in original omitted]
Switzerland’s Criminal Procedure Code (2007), as amended to 2012, which regulates the prosecution and adjudication by the federal and cantonal criminal justice authorities of offences under federal law, including war crimes, states:
Art. 54 Scope of Application of this Code
1. The provision of international mutual assistance and the mutual assistance proceedings are governed by this Code only to the extent that other federal acts and international agreements make no provision therefor. 
Switzerland, Criminal Procedure Code, 2007, as amended to 2012, Article 54(1).
In 2008, in its sixth periodic report to the Committee against Torture, Switzerland stated in the section on universal jurisdiction:
The military justice system has had occasion, on the basis of article 3 (1), sect. 9, and articles 108 to 114 of the Military Criminal Code, to prosecute and try alleged war criminals (violation of the Geneva Conventions of 12 August 1949). During the reporting period, the military courts handled 25 such cases. … Of the two cases concerning Sierra Leone, one … was the subject of reciprocal judicial assistance. 
Switzerland, Sixth periodic report to the Committee against Torture, 18 March 2009, UN Doc. CAT/C/CHE/6, submitted 2 July 2008, § 110.