Sub-State entities like Wales or Scotland in the UK; Wallonia and Flanders in Belgium; Bavaria and the other German Länder; the Austrian Länder; or the Basque Country, Catalonia, Galizia and some others in Spain, do have, among many others in the whole of Europe, a key role therefore and are facing with difficult legal and institutional challenges before the EU, due to their current difficulties to actively participate within all EU levels whatsoever. The problems in reaching a peaceful institutional agreement on all the aforementioned are even greater when we talk about the EU as the fruit of an international treaty, and therefore, through the concept that avoids Sub-State entities taking part directly within EU decision making processes. In certain sense, we can talk of the EU as a real fruit of an international treaty. However, it has a clear will for political integration and this requires as well dealing with Sub-State participation at all levels. This means that in an international organisation looking for integration, the Sub-State approach recognised at domestic levels needs to become a part of the EU.