Switzerland, national Obligatory referendum [LOR] - Obligatorisches Referemdum

Art. 140 Mandatory referendum
1 The following must be put to the vote of the People and the Cantons:
a. amendments to the Federal Constitution;
b. accession to organisations for collective security or to supranational communities;
c. emergency federal acts that are not based on a provision of the Constitution and whose term of validity exceeds one year; such federal acts must be put to the vote within one year of being passed by the Federal Assembly.
2 The following shall be submitted to a vote of the People:
a. popular initiatives for a complete revision of the Federal Constitution;
b. popular initiatives for a partial revision of the Federal Constitution in the form of a general proposal that have been rejected by the Federal Assembly;
c. the question of whether a complete revision of the Federal Constitution should be carried out, in the event that there is disagreement between the two Councils.

References: Federal Constitution of Switzerland, 1999, status:as of Sept. 23, 2012

Obligatory Referendum in certain cases