The first two referendums (on constitutional amendment – Article 15.1 and Article 3.1.1 - and on the laws of ratification of international treaties that change the national territory – Article 15.2 and Article 3.1.3) are mandatory pursuant to Articles 158 and 73 of the Constitution respectively. They are binding if a 50% turnout threshold is met (Article 116.5) and if the decision is supported by more than half of participating voters (Article 116.6).