In today's globalizing world, which is formally based on state sovereignty but in which the latter is called into question by economic, cultural and technological trends, new institutional frameworks need to be designed to allow people, goods, services and ideas to move across legal systems. The European Union provides an interesting model in this regard. Looking at the EU institutional model for achieving legal interoperability, this case-study explains how supranational law can achieve the interoperability of a diverse array of legal systems to attain larger policy goals, while pointing to the fact that lack of coherence between different legal orders (supranational vs. national) can be an obstacle to legal interoperability.