JY, an Estonian national, applied for Austrian nationality. As Austria operates a 'single nationality' approach, JY renounced her Estonian nationality after receiving an assurance that she would be granted Austrian nationality once proof of her renunciation was given. This assurance was subsequently revoked due to the applicant committing two road traffic offences, leaving her stateless. In its judgment, the CJEU confirmed that the situation falls within the scope of EU law, and that the authorities' decision to revoke an assurance to grant Austrian nationality was incompatible with the principle of proportionality considering the gravity of the offences committed. The Court noted that the concepts of ‘public policy’ and ‘public security’ must be interpreted strictly and clarified their meaning, concluding that it did not appear that JY represented a genuine, present and sufficiently serious threat affecting one of the fundamental interests of society or a threat to public security in Austria. It also held that traffic offences, punishable by mere administrative fines, cannot be regarded as capable of demonstrating that the person is a threat to public policy and public security which may justify the permanent loss of their EU citizenship.
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.