Quorum requirements for a referendum to be valid
Costa Rica
Answer
Optional referendum - turnout quorum
Source
Political Constitution of Costa Rica (ConstituciónPolítica de la República de Costa Rica)
http://aceproject.org/ero-en/regions/americas/CR/costa-rica-constitucion-politica-de-la-republica
Comment
Results of the referendum are valid and mandatory if the turnout is of at least 30% of the registered voters in the case of law proposals; and at least 40% in the case of constitutional amendments.
