Groups of companies are today key players in international trade through their crossborder activities. Their asset management – sometimes to the detriment of a subsidiary – or tax optimisation offered by a multitude of laws applicable to their subsidiaries make it essential to regulate groups more closely. It is unanimously accepted in France or the UK, for example, that the group of companies does not have its own nationality or a single lex societatis. However, this classic solution could be revisited and the group of companies could be apprehended as a single legal unit in specific cases. Today, few national laws deal with groups of companies as a legal unit. Very often, these are scattered provisions. In many European states, an economic unit of the group can sometimes be retained by certain legislative and regulatory provisions but also by the courts such as in competition law or in tax and social matters. The purpose of this article is to demonstrate that regulation of groups of companies deserves to be revived by the European authorities and that the economic, political and social challenges are considerable for all member states of the European Union and beyond. Indeed, the Court of Justice of the European Union has shown real normative power with regard to groups of companies, due to the absence of a directive or regulation applicable to groups. The German legislation on groups of companies is a prime example and the regulations relating to the European company remind us that a consensus is possible at the level of the European Union.