The principle of equal treatment and the prohibition of any discrimination on grounds of nationality have been enshrined in Union law since the founding Treaties.
Tá prionsabal na córa comhionainne agus toirmeasc ar aon chineál idirdhealaithe ar fhorais na náisiúntachta cumhdaithe i ndlíthe an Aontais ó aimsir na gConarthaí bunaidh.