The chief concern of this book is to discuss a democratic legitimation for modern law. Investigation is therefore steered towards current debates on processes of Europeanisation and the issue of self-constitutionalisation of a democratic polity. This turns out to be a complex concept referring to the threefold constitutionalisation: legal, institutional and horizontal, and hence to processes of evolutionary constitution making as well as institutional and societal constitutionalisation. Developing democratic legitimation in post-conventional terms rests on the presumption of increasing the processes of incrementally rationalising lifeworlds and unveils the role of the practical power of judgement transferred from the concept of a (monological) subject to the (dialogical-discursive) public spheres.