The ECJ has held that this Article confers a
directly effective right upon citizens to reside in another Member State.
[17][18] Before the case of
Baumbast,
[18] it was widely assumed that non-economically active citizens had no rights to residence deriving directly from the EU Treaty, only from directives created under the Treaty. In
Baumbast, however, the ECJ held that (the then)
[19] Article 18 of the EC Treaty granted a generally applicable right to residency, which is limited by secondary legislation, but
only where that secondary legislation is proportionate.
[20] Member States can distinguish between nationals and Union citizens but only if the provisions satisfy the test of proportionality.
[21] Migrant EU citizens have a "legitimate expectation of a limited degree of financial solidarity... having regard to their degree of integration into the host society"
[22] Length of time is a particularly important factor when considering the degree of integration.