Chapter 5 addresses the controversies as to the law applying to cyber warfare. It summarises the detailed jus ad bellum and jus in bello rules that a group of Western experts agreed in the Tallinn Manual and contrasts this with the less granular recommendations of a more inclusive, UNGA authorised Group of Governmental Experts that considered Information and Communication Technologies. The failure of that Group to adopt a report in 2017 is assessed. After considering the relative merits of the two approaches, the Chapter discusses the draft Code of Conduct proposed by Russia, China and certain other states. In the peacetime context, striking a balance between interests of free speech, privacy and security emerges as a core issue addressed in domestic law, some examples of which are cited. Fake news, allegations of electoral cyber interference and intellectual property theft are among the challenges that feature. Data protection and other issues associated with the Internet of Things are analysed e.g. by reference to the General Data Protection Regulation. The European approach to privacy rights is noted and the Chapter concludes with a brief assessment of relevant domestic law provision in China, Russia and India.