An Austrian national by birth transferred his residence to Germany and naturalised as a German national. The naturalisation in Germany had the effect, in accordance with Austrian law, of causing him to lose his Austrian nationality. The German authorities later withdrew the naturalisation with retroactive effect, on the grounds that the applicant had not disclosed that he was the subject of a criminal investigation in Austria on account of suspected serious fraud, and that he had thus obtained German nationality by deception. The Court held that it is not contrary to EU law for a Member State to withdraw nationality obtained by deception, even if it results in losing EU citizenship, so long as the decision observes the principle of proportionality. Observance of the principle of proportionality requires the person concerned to be afforded a reasonable period of time in order to try to recover the nationality of their Member State of origin.
The case had been brought before the ECJ for a preliminary ruling, leading to its famous Rottman judgment (CJEU, C-135/08 Rottmann, judgment of 2 March 2010). The Federal Administrative Court rules on the case after the ECJ's judgment. The applicant lost his Austrian nationality when he naturalised in Germany, but his German naturalisation was later revoked as he committed fraud in the naturalisation procedure, rendering him stateless. The Federal Administrative Court upheld the administrative decision to withdraw the German nationality despite the uncertainty about the restoration of the Austrian nationality of the applicant.