Issues in relation to which referendums are optional at the national level

Nepal
Constitution of Nepal
(adopted in 2007)
http://www.wipo.int/wipolex/en/text.jsp?file_id=189180
Article 157(1).
Save as otherwise provided elsewhere in thisConstitution, if a two-thirds majority of the total number of the then membersof the Constituent Assembly decides that it is necessary to decide any issue ofnational importance through referendum, such issue may be decided throughreferendum