This book is about legal theory and legal reasoning. In particular, it seeks to examine the relations that obtain between law and a theory of law and legal reasoning and a theory of legal reasoning. Two features of law and legal reasoning are treated as being of particular importance in this regard: law is institutional, and legal reasoning is formal. These two features are so closely connected that it is reasonable to believe that in fact they are simply two ways of looking at the same issue. This becomes clearer as the focus of the book shifts from the institutional nature of law to the consequences of this for legal reasoning, and which is the principal focus of the book. The author received the European Academy of Legal Theory award in 2000 for the doctoral dissertation on which this work was based.