Whereas the three European Communities all have legal personality, and are therefore subjects of international public law, the European Union is simply a Union of States without legal personality of its own, and without the capacity to act at international level. On 21 November 2001, the Committee on Constitutional Affairs of the European Parliament submits a report containing proposals for the simplification of the Union's structure and the recognition of its single, legal personality.

On 1 October 2002, the European Convention Working Group III presents its final report on the consequences of explicit conferral of legal personality on the European Union and on the consequences of a merger of the Union's legal personality with that of the European Community.

In an article published in 2001 in the Revue du Droit de l’Union Européenne, Armin von Bogdandy puts forward the argument that the European Union (EU) should be a single umbrella organisation for all of the European Communities.

Contribution by Pierre Pescatore, former Judge of the Court of Justice of the European Communities, to a joint publication produced by the European Commission in 2002 on the occasion of the 50th anniversary of the European Coal and Steel Community (ECSC). In his text, Mr Pescatore explains, by means of a historical review of the founding Treaties, the principles and concepts which determined the structure of the ECSC and which subsequently provided the foundations of that of the European Economic Community (EEC).

In the context of the simplification and merger of the Treaties establishing the European Communities, as well as of the drafting of a constitution for the European Union, Klaus Hänsch, Member of the European Parliament, presents to the European Convention a contribution on the future of the Euratom Treaty.

In an article published on 18 November 2002, the French daily newspaper Le Figaro reports on the question of nuclear safety in the future enlarged Union and particularly describes the supervisory powers held by the European Commission on the basis of the Euratom Treaty.

Dans cet article paru en mars 2004 dans le quotidien luxembourgeois Tageblatt, Ben Fayot, député du Parti ouvrier socialiste luxembourgeois (POSL/LSAP), plaide pour la dérogation du Traité Euratom à une époque où les priorités de la politique énergétique ne sont plus du tout les mêmes qu'en 1957.

Le 7 septembre 2004, alors que la Commission européenne décide d'entamer une procédure d'infraction à l'encontre du Royaume-Uni pour non respect du traité CEEA/Euratom, le quotidien français Le Monde se fait l'écho de la stratégie de la Commission pour défendre, sur la base des dispositions du traité, une politique de transparence et de sécurité dans le secteur de l'énergie nucléaire.