This book’s aim is to take seriously the legal theoretical thesis that the law has a double dimension: a ‘real’ or ‘conventional’ dimension, which is somehow a matter of course and a reflection of the concrete legal practice in the world of facts, and an ‘ideal’ or ‘normative’ dimension, which one finds in the aspi¬rations and claims that accompany that same legal practice and facts. Law is factual, but it is also ideal and/or normative, and this is in the common percep¬tion of citizens and legal practitioners related to a notion of justice. This double dimension of law has been articulated in different ways by several philoso¬phers of law and legal scholars, and has recently found a powerful elaboration in Professor Robert Alexy’s theory of the nature of law. In this book we take as a starting point Professor Alexy’s proposal and at the same time attempt to present an original discussion about law and rights. As a matter of fact it is legal rights and principles that best express what is commonsensically meant by the ideal and normative dimensions of law.