Judgment of the Court of Justice in Case C-127/08

The right of a national of a non-member country who is a family member of a Union citizen to accompany or join that citizen cannot be made conditional on prior lawful residence in another Member State.

Under the Directive on free movement of Union citizens, all citizens have the right to move and reside in the territory of another Member State as workers or students or if they have comprehensive sickness insurance and sufficient funds not to become a burden on the social assistance system. The family members of a citizen of the European Union have the right to move and reside in the Member States with that citizen. They can enter a Member State if they have an entry visa or residence card issued by a Member State.

The Irish legislation transposing that directive provides that a national of a third-country who is a family member of a Union citizen may reside with or join that citizen in Ireland only if he is already lawfully resident in another Member State

Document: http://curia.europa.eu/