The U.K.’s Home Office is acting unlawfully by removing residence rights from EU nationals if they fail to apply twice for the right to stay in the U.K. after Brexit, a senior judge ruled.

The High Court of England and Wales ruled Wednesday that an EU citizen who lived in Britain before Brexit can lose their right of residence only in very specific circumstances, which are clearly defined in the EU-U.K. Withdrawal Agreement. These should not include failure to upgrade from so-called “pre-settled” to “settled status.”

Under the U.K.’s current system, citizens from the bloc who settled in Britain before Brexit for less than five years can apply for “pre-settled status,” allowing them to preserve their right to live, work and access U.K. public services such as education.

The government then requires these people to make a second application within five years of being granted this “pre-settled status,” either for full, so-called “settled status” or for a further period of pre-settled status. If they fail to apply for either, the Home Office will consider them to be unlawfully present in the U.K. and no longer entitled to exercise their residence rights such as access to healthcare or the right to work.

A year ago, the Independent Monitoring Authority (IMA), Britain’s watchdog for the rights of EU citizens in the U.K. and Britons in the EU, launched judicial review proceedings against the Home Office’s policy, arguing it failed to uphold the rights of EU nationals who lived in Britain for less than five years before Brexit.

Lord Justice Lane found that the Home Office was acting unlawfully by imposing a requirement to upgrade residence status, and said that those granted pre-settled status are entitled to reside permanently in the U.K. once they have lived in the country for the required five-year period.

This policy has been a source of bad blood between the U.K. government and the European Commission, which last February accused the U.K. of splitting EU citizens into two cohorts and being less generous with them than the Brexit divorce deal requires.

Over 2 million nationals from EU and European Economic Area countries have been granted pre-settled status. Unless the policy is changed, they will be at risk of losing their rights from August 2023, when the first pre-settled statuses are set to expire.

But if the ruling is confirmed, the government could be forced to change to its EU Settlement Scheme in order to prevent that scenario.

Home Office Minister Simon Murray said the department was “disappointed by this judgment,” and intends to appeal.

“EU citizens are our friends and neighbors, and we take our obligations to securing their rights in the U.K. very seriously. The EU Settlement Scheme goes above and beyond our obligations under the Withdrawal Agreement, protecting EU citizens’ rights and giving them a route to settlement in the U.K.,” he said.

Monique Hawkins, policy and research officer at the3million group, which campaigns for the rights of EU nationals in the U.K., welcomed the judgment.

She said the ruling “stands to protect vulnerable citizens who are granted pre-settled status under the EU Settlement Scheme, and who could lose their right to work, rent, travel, benefits, healthcare and more — just for not making a further application in the years ahead.”