In this chapter, I will consider and criticize the implicit normative implications that the ‘classical’ positivistic conceptions of law have for our understanding of constitutionalism. By ‘classical’ positivistic conceptions of law, I refer to the most outstanding positivist legal theories of the nineteenth and early twentieth century, the kind of Austin, Gerber, Laband, Jellinek or Santi Romano. Such authors played a major role in the theoretical development of law in Europe, especially in public law. Their thought can still be said to have a considerable influence on the way in which law is conceived and analysed in Europe. A critical scrutiny of the central tenets of their theories is thus quite pertinent at the very time at which a constitution is being written for the European Union.1 This is so because the way in which law is conceptualized has a major feedback on the critical standards applied to constitution-making processes and to their outcomes, that is, the actual rights and values it positivizes. Therefore, what conception of European law is sustained has a direct impact on how the European constitution-making process and the eventual European constitution are/will be assessed.