How can normative claims be rationally justified if one cannot refer to a given moral world, and any norm established by social practice can be called into question? The only foundation of normative claims seems to be the judgements of the norm addressees themselves. But how can norm addressees be bound by norms that they themselves establish? This is the puzzle of autonomy as self-legislation. It also concerns the normative claim of law, which, moreover, pretends to be authoritative and, thus, seems to exclude individual autonomy. Hence, the problem regarding law is not only to justify its normative claim, but also to construct its authoritative claim on the basis of the idea of autonomy as self-legislation.