Freedom of movement, as described in Article 45 of the EU Treaty, is perhaps the most sweeping of Europe’s four indivisible freedoms, but also clearly the one that has been politically the most contentious. It allows European citizens to move freely, reside and work in all 28 countries of the EU, giving them in the process the same rights as nationals of the country they choose to reside in with respect to accessing social benefits such as health care or education; to most Europeans, freedom of movement and residence for persons in the EU is the cornerstone of Union citizenship.

The right to freedom of movement as enshrined in the Treaty refers to European citizens only and relates exclusively to intra-EU movement; it has therefore entirely different characteristics from the migrant flows coming into the EU from other parts of the world, which are behind many of the tensions felt in European societies. Furthermore, the rights accompanying freedom of movement within the Union are not unconditional; the European Court of Justice in a series of successive rulings has defined its scope and limits, while EU member states can set their own conditions for access to benefits. In some countries, for example, job seekers can only claim out-of-work benefits if they have previously worked; in others only after a waiting period of several months; even where there is immediate entitlement to out-of-work benefits, job seekers must prove they are actively looking for paid employment.

Nevertheless, concerns about the impact that labour flows from poorer to richer EU countries would have on jobs and on European social protection systems have long persisted, and this despite the fact that such labour flows represent also one of the requirements for the common currency to function properly. They have become more pronounced with each wave of accession into the EU, but especially since the latest accession of countries with significantly lower GDP per capita.