When it comes to the internal market, one of the 4 primary fundamental rights is the free movement of people. European Union treaties provide for the right of movement and residence in the territories of member States subject to certain limitations and conditions established by them. In addition to the treaties, the free movement of EU citizens and the members of their families as well as freely residing in the territory of Member States are regulated in Directive 2004/38/EC of the European Parliament and of the Council of 29 April 2004.

Spanish Royal Decree 240/2007, of 16 February provides for the entry, free movement and residency in Spain of citizens of European Union Member States and other States which have signed the European Economic Area Agreement. Extended families are also regulated therein at this time.

As concerns extended family members, Directive 2004/38/EC states that Member States must facilitate the entry and residency of other members of the family of a Union citizen in order to maintain family units. Extended family refers to any other member of the family irrespective of their nationality who accompany or are reuniting with the individual and can prove on the application that they are dependants or live with the Union citizen receiving residency in their country of origin or, on the other hand, that it is necessary for the Union citizen to take responsibility for their personal care for health reasons. It also covers a partner with whom the Union citizen has a stable relationship.
If said members are required to obtain an entry visa as per Regulation EC 539/2001, which provides a list of third party countries whose nationals are required to do so in order to cross the exterior borders as well as nationals who are exempt from this obligation, the visa application must be attached to the documented proof of dependency and kinship or the serious health reasons as well as proof of the stable relationship between the most important family members.

Member states may establish requirements as well as criteria for determining when applications for extended family members are admissible. Extended family members will be issued an EU citizen family residency card when they fulfil the requirements for it. As mentioned, the level of financial or physical dependence, the degree of kinship with the EU member state citizen or, where appropriate, the seriousness of the disease will be assessed. On the other hand, the existence of a common-law partnership will be assessed based on a period of co-habitation of at least one continuous year.