The recently developed term “legal interoperability” addresses the process of making legal rules cooperate across jurisdictions. It can facilitate global communication, reduce costs in cross-border business and drive innovation, thereby creating a level playing field for the next generation of technologies and cultural exchange. This paper portrays legal interoperability as a spectrum with full harmonization of normative rules between jurisdictions on one end and a complete fragmentation of legal systems on the other, the ideal existing between the two poles. In cyberspace, legal interoperability should be designed to function on four broad layers of complex systems: technology, data, human elements and institutional aspects. The regulatory models of harmonization, standardization, mutual recognition and other approaches (such as reciprocity or cooperation) should be mapped with the existing sources of law, identifying the most appropriate instrument for a given substantive topic. Legal interoperability is a complex issue and the monetary costs of non-interoperable laws in a highly networked world will increase. If an adequate level of legal interoperability is not achieved and a far-reaching fragmentation of legal jurisdictions prevails, the likelihood of dominant states enlarging the geographical scope of their laws through extraterritorial application increases. Due to this complexity, nuances in the design of rule-making processes must gain importance so that unintended consequences of regimes that are not legally interoperable can be avoided.