Legal provisions for mandatory referendums at national level

Constitution of Jamaica
(Adopted 1962, last amended 2011)
http://pdba.georgetown.edu/Constitutions/Jamaica/jam62.html

Electoral Commission (Interim) Act
(Passed 2006)
http://www.moj.gov.jm/sites/default/files/laws/The%20Electoral%20Commission%20%28Interim%29%20Act%20pdf.pdf

As stipulated in Section 49.3.d.ii of the constitution, a mandatory referendum takes place if a bill that amends the sectionsspecified in 49.3 passes both Houses.