Legal provisions for optional referendums at national level

Bermuda
Referendum Act, 2012
http://www.bermudalaws.bm/Laws/Consolidated%20Laws/Referendum%20Act%202012.pdf
Referendum Act, 2012
Holding of referendum and answer to question
6. (1) Where an Act requires that a referendum be held—
a) the question or questions to be answered at the referendum shall be set out in that Act; and
b) subject to anything to the contrary in that Act, the referendum shall be conducted in accordance with the provisions of this Act.
Legislaturecan pass an Act that will require a referendum to take place on any issue. Bermuda’sReferendum Act 2012 provides legislative basis for such ad hoc referendums.