When Citizenship Vanishes: The Unfinished Business of Involuntary Loss of European Nationality

The Question Worth Asking

What does it mean to be European? The answer, it turns out, depends entirely on which member state issued the passport. And that passport can be revoked – sometimes automatically, sometimes arbitrarily, and often without the proportionality assessment that European law increasingly demands.

The ILEC project, which ran from 2013 to 2014, set out to answer a deceptively simple question: how do EU member states take citizenship away from people who don't want to lose it? The research, involving six partner institutions including Maastricht University and the European University Institute, produced the first comprehensive comparative inventory of involuntary loss provisions across all 28 EU member states (including Croatia, which was joining at the time).

The findings matter beyond legal scholarship. They reveal a fundamental tension at the heart of European integration – one that becomes more urgent as digital identity systems, automated decision-making, and AI-assisted border management reshape how states recognize and categorize their populations.

What the Research Actually Found

According to the comparative analysis produced by Gerard-René de Groot and Maarten Peter Vink, member states can strip nationality for a remarkably diverse set of reasons:

Voluntary acquisition of foreign citizenship remains the most common trigger. But the rules vary wildly. Some states automatically revoke nationality the moment a citizen naturalizes elsewhere; others permit dual citizenship without restriction.

Fraud in the naturalization process provides grounds for deprivation in most member states, but the standards differ. Some require proof of intentional deception; others apply strict liability. The time limits for challenging fraudulent acquisition range from a few years to unlimited.

Permanent residence abroad triggers automatic loss in several countries. The Netherlands, notably, strips citizenship from dual nationals who live outside the EU for ten consecutive years – a provision that generated significant litigation and eventually reached the Court of Justice of the European Union.

Seriously prejudicial behavior and foreign military service can result in deprivation in some states, though the definitions of what constitutes "seriously prejudicial" vary considerably.

Loss of family relationship – when paternity or maternity is annulled – can retroactively eliminate citizenship acquired through descent, sometimes leaving individuals stateless.

The research identified what it called "promising practices" across the Union, but the overall picture was one of fragmentation. As the CEPS policy brief noted, member states remain "in principle autonomous in nationality matters," which means their rules on loss of nationality – and therefore loss of EU citizenship – "differ considerably."

The Tjebbes Turning Point

The ILEC project's findings gained new relevance in 2019, when the Court of Justice ruled in the Tjebbes case (C-221/17). According to the EU-CITZEN analysis of that judgment, the Court concluded that "the principle of proportionality should also be applied in cases where the loss of Member State nationality and the associated loss of European citizenship occurs by operation of law."

This was significant. The Court held that even automatic loss provisions – those that strip citizenship without any individual decision by authorities – must allow for proportionality assessment in each specific case. The same applies when a parent's loss of nationality extends to minor children: "the proportionality of the extension has to be assessed separately, with special attention for the best interests of the child."

The implications ripple across multiple member states. The EU-CITZEN report identified Belgium, Denmark, Finland, Spain, and Sweden as countries whose residence-abroad provisions may need revision. It also flagged potential problems with automatic loss provisions in Slovakia, the Netherlands, Spain, Austria, and Germany.

Why This Matters for AI Governance

The connection to artificial intelligence might not be immediately obvious. But consider what happens when automated systems make or inform decisions about identity, status, and belonging.

Digital identity infrastructure increasingly relies on algorithmic verification. Border management systems use AI to assess risk and flag anomalies. Administrative databases determine who qualifies for services, benefits, and rights. When these systems interact with citizenship status – a status that can be lost automatically, without individual assessment – the potential for harm multiplies.

The ILEC research revealed that many member states lack adequate procedural safeguards for challenging loss of nationality. Some provisions operate retroactively, deeming citizenship "never to have been acquired" rather than lost. The EU-CITZEN report calls these "quasi-loss" situations, where "the nationality is not lost, but deemed never to have been acquired, without any possible assessment of proportionality."

For anyone building or governing AI systems that touch on identity verification, the lesson is clear: the underlying legal status these systems rely upon is far less stable than it appears. A person who was a citizen yesterday may not be one today – not because of anything they did, but because an automatic provision triggered without their knowledge.

The Disagreement Beneath the Disagreement

The debate over involuntary loss of nationality often presents as a sovereignty question: do member states have the right to determine who belongs to their political community? But this framing obscures the real tensions.

The first tension is between national autonomy and European citizenship. EU citizenship is derivative – it exists only because someone holds member state nationality. But the rights attached to EU citizenship are substantial: free movement, residence, non-discrimination, consular protection. When a member state strips nationality, it simultaneously strips these European rights. The question is whether European law should constrain how member states exercise this power.

The second tension is between legal certainty and individual justice. Automatic loss provisions offer clarity: if condition X is met, citizenship is lost. But the Tjebbes judgment suggests that clarity cannot come at the expense of proportionality. Every case must be assessable on its merits. This creates administrative complexity but protects against arbitrary outcomes.

The third tension is between past practice and future technology. The ILEC research documented rules developed in an era of paper records and physical presence. As identity becomes increasingly digital and administrative decisions increasingly automated, these rules will interact with systems their drafters never imagined.

What Would Have to Be True

For the current patchwork to be acceptable, one would have to believe that the accidents of birth – which member state issued the passport – should determine the security of one's European rights. That a Dutch dual national living in Canada for eleven years deserves different treatment than a Spanish dual national in the same situation. That automatic provisions requiring no individual assessment are compatible with fundamental rights.

The Tjebbes judgment suggests the Court of Justice does not believe this. But the judgment also leaves much unresolved. How should proportionality assessments be conducted? What circumstances are relevant? How far back should remedies extend?

The EU-CITZEN report notes that because the Court "rejected the request to limit the temporal effect of the judgment, an ex post assessment of the proportionality of the relevant loss provisions may have to be realised for all cases where the loss of nationality happened after the introduction of European citizenship on 1 November 1993."

That is a substantial administrative undertaking. It is also, arguably, what justice requires.

The Question That Remains

The ILEC project ended in 2014. The Tjebbes judgment came in 2019. The legal landscape continues to evolve. But the fundamental question the research surfaced remains unanswered: what does European citizenship mean if it can be lost through the operation of 28 different national systems, each with its own logic, each with its own gaps?

For policymakers designing digital identity infrastructure, for technologists building verification systems, for governance scholars thinking about algorithmic accountability – this is not an abstract question. It is the ground on which everything else is built.

The strongest version of the argument for national autonomy holds that citizenship is the most fundamental expression of political community, and that communities must retain the power to define their own membership. The strongest version of the argument for European constraint holds that derivative citizenship creates derivative obligations – that if European rights attach to member state nationality, European standards must govern how that nationality can be lost.

Both arguments have merit. The question is which one breaks down first when applied to real cases – to the Dutch woman who lost citizenship while caring for her elderly mother in Switzerland, to the child who lost status because a parent's naturalization was later deemed fraudulent, to the person who discovers their citizenship was "never acquired" because of a bureaucratic determination made decades ago.

The ILEC research did not resolve these tensions. It made them visible. That remains its most valuable contribution.