The interaction between state, transnational and international law is overlapping and often conflicting. Yet despite this messiness and multiplicity, law still creates obligations for its subjects. Despite its plurality, law still claims some kind of authority.
The implications of this plurality of law can be troubling. It generates uncertainty for law-users over which law they are bound by, or for law-makers over the limits of their authority. Thus the practical problem is not plurality of law in itself, rather confusion over law's authority in such pluralist circumstances.
Roughan...

The pluralist turn in jurisprudence has led to a search for new ways of thinking about law. The relationships between state law and other legal orders such as international, customary, transnational or indigenous law are particularly significant in this development. Collecting together new work by leading scholars in the field, this volume considers the basic questions about what would be an appropriate theoretical response to this shift: wow precisely is it to be undertaken? Is it called for by developments in legal practice or are these adequately addressed by current legal theory? What...

How can legal authority be explained beyond the sovereign state? Roughan argues that instances of transnational and international law, along with overlapping constitutional orders, should be regarded as having shared, interdependent, and relative authority.