A Rule Book on the Shelf? Tallinn Manual 2.0 on Cyber Operations and Subsequent State Practice

Abstract

The Tallinn Manuals represent a notable attempt by prominent international lawyers to facilitate the regulation of cyber operations by international law. In this article, we attempt to evaluate the degree to which international law, as reflected inter alia in the Tallinn Manuals, is influencing now and is likely to influence in the near future State conduct. This evaluation is based on mapping the principal reactions to the Tallinn Rules found in the academic and professional legal discourse, and – more significantly – through investigation of a 11 major incidents occurring after the first Tallinn Manual was published, which appeared to invite the application of international jus ad bellum and jus in bello norms. Our principal findings are that there appears to be only limited support in actual State practice and opinio juris for certain key Rules in the Tallinn Manuals. More significantly, several States heavily engaged in cyber operations appear at this point in time to have a limited interest in promoting legal certainty regarding the regulation of cyberspace.