Over the years Robert Alexy has developed a systemic approach to legal theory, an approach whose dimensions include discourse theory, principles theory, and a non-positivist conception of law. Principles theory is found at the very core of Alexy's system. Constitutional rights, he argues, are best understood as principles, and collisions between constitutional rights - understood now as competing principles - are resolved by balancing their respective weights. Critical examinations of Alexy's work on principles theory and on the other dimensions of his system are presented here, along with a contribution on human rights, one of Alexy's more recent foci. Alexy's work is receiving ever greater attention, both at home, in Germany, and abroad, with translations of his treatises and papers into many languages. The authors of the contributions aim to promote enquiry into Alexy's project. While their general approach is that of analytical jurisprudence, the individual contributions reflect great variety in their respective assessments of Alexy's seminal work.
