This book brings together the fruits of different traditions in legal philosophy and draws on them to develop a systematic thesis on the concept of law. The respective strengths of each tradition can thus be used to elucidate the phenomenon in question. The work explores the underlying question of how current phenomena of transnational law are best understood by legal theory. The traditions dealt with are, on the one hand, Jürgen Habermas's critical theory and, on the other, H. L. A. Hart's analytic jurisprudence. The thesis is that the key to a fruitful dialogue and comprehensive understanding is to appreciate that the concept of law is not state-centered and must reflect relationships to other legal systems.