Article 18 TFEU [Combating Discrimination Based on Nationality]

The prohibition of discrimination on grounds of nationality was established in the founding Treaties from the beginning of the process of European integration. In a system based on the coexistence of a number of national and EU legal orders, that prohibition has assumed a key role, encouraging the creation of the internal market and the free movement between MS. The CJEU itself has specified this rule to be of fundamental importance and producing direct effects, both vertical and horizontal. By virtue of this importance, the CJEU held that this rule would apply to the effects of situations that arose before the accession of all new MS to the EU.