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

Bhutan

Answer

Any issue of national importance, except those excluded

Source

NationalReferendum Act

http://www.election-bhutan.org.bt/index.php?option=com_content&id=167&Itemid=92

Article 4 of the National Referendum Act provides that 'National Referendum may be initiated: (a) On the Command of His Majesty the Druk Gyalpo if He deems a Bill is of national importance but has not been passed in a joint sitting of Parliament; (b) If a petition on issue of national significance is made by not less than 50% of the total number of members of all Dzongkhag Tshogdues'

Comment