When I first came across Johnson and Post's article, ‘Law and Borders – The Rise of Law in Cyberspace’ (1996), in 1998, it impressed me. The authors seem to prove quite conclusively that States could not possibly, in all rationality, apply their laws to online activity and that this new cyberspace was completely beyond their legitimate and actual supervision. And yet, at the same time, the first cases were emerging where States did exactly that. Over the following years, while investigating competence questions in cyberspace, the article has stayed with me and my views on it have almost come full circle: from being fascinated by it and utterly convinced of its accuracy, to rejecting most of it, to finally admiring the brilliance that lies in the confident simplicity of its core ideas and in its provocative imperfections. If this book can follow suit, it does well.

Researching for, and writing, this book was a humbling experience. I was left, at every stage, with the feeling that there was so much more to read and know. Being a Jack-of-all-trades is perhaps partly a genetic predisposition and partly unavoidable given the nature of the competence inquiry, spanning across most substantive legal fields.