The Court held that it is not contrary to EU law for Member States to withdraw citizenship obtained by deception, even if the effect is to also withdraw citizenship of the Union, so long as the decision observes the principle of proportionality.
The applicant acquired Austrian nationality in 1995 and renounced her former Turkish nationality in 1996 as a condition for retaining the Austrian nationality. In 2018 the Austrian authorities declared that she has no longer been an Austrian national since 1997 as it appeared that she voluntarily re-acquired her Turkish nationality at that time, which is a ground for automatic loss of Austrian nationality. The Court set aside the determination of loss of Austrian nationality as it did not carry out a proportionality test on the basis of the Tjebbes judgment.
The applicant received assurance of obtaining Austrian nationality if she renounces her Estonian nationality. After the renunciation, it appeared that the applicant committed two administrative offences related to her driving, which in addition to the eight she committed previously were considered as an indication of her no longer fulfilling the public order requirement for naturalisation. This resulted in the withdrawal of assurance of obtaining Austrian nationality, leaving the applicant stateless.
The applicant was issued an assurance that she will acquire Austrian nationality if she renounced her former Serbian nationality, which she did. However, after the assurance was issued the applicant committed a number of administrative offences, leading to the assurance being withdrawn after the renunciation of the former nationality has already taken place, resulting in the applicant's statelessness. The Court emphasised the constitutional significance of a letter of assurance of acquisition of nationality, and sided with the applicant.
In order to acquire Austrian nationality, the applicant renounced her Turkish nationality in 1997. Over a decade later it came to light that she has re-acquired Turkish nationality in 1998, which according to Austrian law resulted in automatic loss of the Austrian nationality. She renounced her Turkish nationality again in 2009, but in 2010 the Austrian authorities confirmed that she was no longer Austrian since 1998. The Court found that this was not in violation of Austria's obligation to avoid statelessness since the applicant's statelessness was not caused by a decision of the Austrian authorities.
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.