The rule of law in cyberspace currently faces serious challenges. From the democratic system to the exercise of fundamental rights, the Internet has raised a host of new issues for classic legal institutions. This book provides a valuable contribution to the fields of international, constitutional and administrative law scholarship as the three interact in cyberspace.The respective chapters cover topics such as the notion of digital states and digital sovereignty, jurisdiction over the Internet, e-government, and artificial intelligence. The authors are eminent scholars and international experts with a profound knowledge of these topics. Particular attention is paid to the areas of digital democracy, digital media and regulation of the digital world. The approach employed is based on a comparative perspective from Germany, the Netherlands, Italy, Portugal and Brazil. One particular focus is on how various legal systems are coping with increasing difficulties in the exercise of democracy with regard to disinformation and hate speech. The roles of legislators, the judicial system and public administrations are analysed in the light of the latest cases, conflicts and technologies. In addition to this comparative approach, the book explores the evolution of rule of law in cyberspace and the upcoming new legal regimes in the European Union and Brazil. Special care is taken to offer a critical review of both the literature and the latest legal solutions adopted and being considered regarding the regulation of cyberspace from a constitutional and administrative perspective. Given its scope, the book will be of interest to researchers and scholars in the field of digital law whose work involves constitutional problems in cyberspace and/or practical problems concerning the regulation of social networks and online commerce.