The article deals with the emergence of powers in the global arena. It aims to illustrate the different paths traced by this phenomenon. A first path consists of bringing national powers beyond their borders, in order to enhance State sovereignty. A second path is the establishment of new global institutions. A third one — perhaps the most effective to date — is based on the increasing protection of fundamental rights worldwide. But there is also a fourth path, a more ambitious one, which seeks to put together all the previous ones in a single map: it is the idea of a world government based on democratic rules: such a challenge must now be dealt with by any branch of public law, from administrative law to constitutional law.