European approaches to the application of international law in cyberspace : a comparative legal analysis

This study examines the positions of European Union Member States (as of April 2024) on how international law applies in cyberspace. Of the 27 Member States, 13 have issued official national positions on the matter. The study is designed to identify commonalities and divergencies among them. The national positions bear on international law found in customary international law and treaties such as the UN Charter. Treaties bind only the parties to the instrument concerned, whereas customary law sets forth legal obligations for all States. Customary law consists of unwritten rules that have "crystallised" due to States engaging in, or refraining from, a particular practice over time out of a sense of legal obligation (opinio juris). National positions such as those examined in this study influence treaty and customary law in two ways. First, they bear on how existing international law rules should be interpreted in the cyber context. The greater the consensus on a particular rule, such as the prohibition of intervention into another State's internal or external affairs, the more authoritative that interpretation becomes. Second, the statements qualify as expressions of opinio juris and, therefore, contribute to the emergence of new cyber-specific rules of customary international law. Accordingly, the positions this study surveys, as a matter of law, exert a powerful influence on international law as it applies to the cyber domain