Zusammenfassung:
In contrast to the attention devoted to the rejection of the EU Constitutional Treaty at French and Dutch referenda; the Spanish referendum, where this Treaty was ratified, remained under-researched by political scientists. This paper analyses the voting behaviour at the Spanish referendum on the EU Constitutional Treaty with the use of quantitative methods and the concept of first and second-order elections. This paper finds that the Spanish referendum was a second-order referendum, because the effects of domestic political issues in Spain had a greater impact on the electoral behaviour of Spanish voters than had genuinely European issues. This finding raises doubts over the suitability of using direct democracy in the EU in order to raise the legitimacy and democratic accountability of the European project.