Spain is one indivisible nation  The Spanish constitution does not allow the holding of referendums on independence by Spanish regions. Spain is a single ‘demos’ made up of all the regions together rather than being separate and simply brought together under one banner. The Constitution says it “is based on the indissoluble unity of the Spanish Nation, the common and indivisible homeland of all Spaniards”. 1  Moreover while referendums may be allowed for “political decisions of special importance” “The referendum shall be called by the King on the President of the Government's  proposal after previous authorization by the Congress.” 2 So the calling of one is first up to the national government to decide one is needed and then requires the approval of the national parliament. In case that was not clear enough it is reiterated in section 149 on the role of the State and Regions “The State shall have exclusive competence over the following matters: Authorization of popular consultations through the holding of referendums.” 3  1 Cortes Generales, Spanish Constitution, 27 December 1978,  Section 2  2 Ibid, Section 92  3 Ibid, section 149