Integration through the cross-border movement of persons, goods, services and capital is a supreme objective of the Union and depends on certain foundational principles which are part of its economic constitution: the removal of barriers of access to national markets; the protection of undistorted competition against restrictions imposed by the Member States and by undertakings; the free cross-border transfer of payments and funds; the recognition, regardless of their country of origin, of market actors’ (i.e. the market subjects’) capacity to acquire rights and obligations; the respect for entitlements which are the objects of market transactions irrespective of where they were acquired; and the acceptance of decentralised decisions taken by private actors as the basis of cross-border transactions, i.e. private autonomy and freedom of contract. Many of these components of an integrated area were far from being ensured in Europe at the beginning of the 1950s.

The Rome Treaty of 1957 created and highlighted some of the instruments needed to ensure unhindered access to national markets and undistorted competition: the basic freedoms ensuring the free movement of persons, goods, services and capital; the prohibition of anticompetitive conduct of undertakings, except for mergers which were prohibited only at a much later stage; the ban on dumping practices which was later repealed; and restrictions on State aid. The pertinent provisions were equipped with a considerable operational force. Where they gave rise to doubt, the Court of Justice has reinforced their vigour, inter alia , by attributing direct effect and primacy to some of them. All in all those provisions have proven their effectiveness over the years and achieved a far-reaching integration of markets. They are embedded in more general principles which have a certain impact on other legal districts and which will deserve a closer look in Chapter XXIII .

By contrast, the private law principles mentioned above were essentially taken by the founders as being acknowledged and pre-existing under national law. The law of the EU was built on foundations laid by national private law, in particular on the laws relating to contract and property.